Re: [Emc-users] Rewiring the BP Again

[Mark]

We had about 10" of snow on the ground before the short melt hit, making 
things a bit soggy.  Then the temps dropped again and we got another 3 - 
4 inches over the last couple of days.  Hopefully, they'll have the 
roads cleared by the time I set out.

Mark

On 01/11/2016 08:14 AM, Peter Blodow wrote:
> Mark, it surely was interesting, when I drove to Traverse City last
> time, some 50 years ago, when I was temporarily a Michigander. Was a
> nice skiing weekend.
>
> Peter
>
> Am 11.01.2016 13:34, schrieb Mark:
>> 8 Degrees and snowing here in Grayling, MI this morning. I have to
>> drive over to Traverse City this morning. Should be interesting. Mark


--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[Mark]

On 01/10/2016 04:23 PM, Dave Cole wrote:
> I understand.I'm working out of town and just came back for the
> weekend.
>
> For me this is a good time to be distracted with too much work.
>
> It helps me ignore the wind gusts to 30 mph, the snow, and the temps
> headed to 8 degrees F for tonight.
> Except that I need to drive a long ways in this crap tomorrow morning.
>
> Dave

8 Degrees and snowing here in Grayling, MI this morning.  I have to 
drive over to Traverse City this morning.  Should be interesting.

Mark

--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[Peter Blodow]

Mark, it surely was interesting, when I drove to Traverse City last 
time, some 50 years ago, when I was temporarily a Michigander. Was a 
nice skiing weekend.

Peter

Am 11.01.2016 13:34, schrieb Mark:
> 8 Degrees and snowing here in Grayling, MI this morning. I have to 
> drive over to Traverse City this morning. Should be interesting. Mark


---
Diese E-Mail wurde von Avast Antivirus-Software auf Viren geprüft.
https://www.avast.com/antivirus


--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[Gene Heskett]

On Monday 11 January 2016 08:35:59 Mark wrote:

> We had about 10" of snow on the ground before the short melt hit,
> making things a bit soggy.  Then the temps dropped again and we got
> another 3 - 4 inches over the last couple of days.  Hopefully, they'll
> have the roads cleared by the time I set out.
>
> Mark
>
Positively balmy down here in WV, 18 degrees this morning, 1/4" of snow 
in the shade.

Winds were high & gusty yesterday though, my 7000 lb WV Cadillac got 
moved sideways about 2 feet at 75 mph, taking me over the right hand 
white line on I-79 as I was approaching the AnnMore turnoff ramp, then 
out of the south when I turned around & went back south to home, 
normally a top gear 75mph trip, it blew the automatic into passing gear 
5 times in that 15 miles to the Jane Lew exit.  Keeps one up on his 
tippy toes for sure. 

OTOH, I learned to drive 66+ years ago in Iowa, and that winter was 
legendary, still remembered by us oldtimers.  Same in Nebraska.  When I 
moved there from Rapid City where I had seen -39F on a tree in front of 
my house in South Canyon back in the middle 60's, the first time I went 
to get a hair cut in a little square block building, grandfathered into 
one edge of a block square city park, the first thing I noticed on the 
wall was a picture taken in 1950, of a smoking stovepipe sticking up out 
of a snowdrift.

Taken from an angle that did not show the front had a shoveled path to 
the front door, it was that barbershop. The stove was by then, in 1971 
propane gas, but it was a coal burning, pot bellied "Warm Morning" in 
1950.  He said he brought 2 buckets with him from his home coal shed 
when he opened up, and again after lunch in those days.

So yeah, WV is balmy.  I think I'll stay till the rapture.:)

> On 01/11/2016 08:14 AM, Peter Blodow wrote:
> > Mark, it surely was interesting, when I drove to Traverse City last
> > time, some 50 years ago, when I was temporarily a Michigander. Was a
> > nice skiing weekend.
> >
> > Peter
> >
> > Am 11.01.2016 13:34, schrieb Mark:
> >> 8 Degrees and snowing here in Grayling, MI this morning. I have to
> >> drive over to Traverse City this morning. Should be interesting.
> >> Mark
>
> --
> Site24x7 APM Insight: Get Deep Visibility into Application
> Performance APM + Mobile APM + RUM: Monitor 3 App instances at just
> $35/Month Monitor end-to-end web transactions and take corrective
> actions now Troubleshoot faster and improve end-user experience.
> Signup Now!
> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

Yes, and I need to start a new thread as new info has been received.

JT

On 1/9/2016 7:49 PM, Dave Cole wrote:
> Just saw your message.
>
> If you keep the VFD powered off, do you still have noise issues ??
>
> Dave
>
> On 1/4/2016 5:19 PM, John Thornton wrote:
>> I have 3 DC power supplies in the drive side, a 5vdc, a 24vdc, and a
>> 170vdc.
>>
>> The 5vdc power supply on the 0v side reads 37.6 ohms with the 0v and 5v
>> sides connected to the 7i77 5v plug. The 7i77 is the only thing it
>> powers up. When I unplug the 7i77 0v reads open so there is a path
>> through the 7i77 5v to ground.
>>
>> The 24vdc power supply is for the limit switches and push buttons. It
>> reads open from 0v to ground.
>>
>> The 170vdc power supply is a bridge rectifier with a large blue cap and
>> a power resistor. See the photo in the link of the current panel. I
>> can't tell which side should be 0v but both sides measure 0.65M ohms to
>> ground. I don't know if that is reading back through the bridge
>> rectifier or the drives. It only powers the three axis drives.
>>
>> Current panel layout http://gnipsel.com/images/bp-knee-mill/bpel06.jpg
>>
>> JT
>>
>> On 1/4/2016 10:48 AM, Bertho Stultiens wrote:
>>> On 01/04/2016 05:34 PM, John Thornton wrote:
 Well I grounded X2 to the main ground and when I started LinuxCNC and
 started to home I got the flurry of sserial errors. So I thought about
 it for a bit and maybe the ground from the computer case to the ground
 block was creating a ground loop so I took it off. Started LinuxCNC and
 immediately go a flurry of sserial errors which locks up LinuxCNC. Mind
 you this is with the 7i77ISOL card between the 5i25 and the 7i77 which
 is supposed to block any noise in the sserial communications. The X2 to
 ground has to go...

 I do have a 7i92 to test out...
>>> My guess is that you have more than one (ground-)loop. You also need to
>>> check how the 0V (DC) line interacts with other devices/converters etc.
>>> wrt. ground and see whether any of them also hook-up to ground somewhere
>>> along the wiring, PCBs or supplies.
>>>
>>> The second type of loops can be (entirely) in the 0V (DC) connection(s)
>>> where multiple paths, with different impedances, impair the integrity of
>>> the signal lines. You need to check how the different DC supplies
>>> interact with the connections as they are. The problem often becomes
>>> visible when you have both high- and low-power devices connecting and
>>> running on the same supply and have the 0V (DC) connected so that it
>>> (can) create(s) a loop.
>>>
>> --
>> ___
>> Emc-users mailing list
>> Emc-users@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/emc-users
> --
> Site24x7 APM Insight: Get Deep Visibility into Application Performance
> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
> Monitor end-to-end web transactions and take corrective actions now
> Troubleshoot faster and improve end-user experience. Signup Now!
> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[Bertho Stultiens]

On 01/10/2016 12:44 PM, John Thornton wrote:
> Well none of the suggestions about star grounding did any good. In
> fact they made the problem worse than before, so bad I could not even
> get 2.6 to run.

That may suggest a couple of things being wrong simultaneously:
1) you may still have loops in the 0VDC which are crossing power
domains. These /are/ hard to detect with many devices connected together;
2) there are impedance mismatches in the signal wiring (this one often
works together with 1);
3) shields may pick up noise they should reject.

The question is how to reduce the practical problems, not how to
eliminate all theoretical problems. That is the hard part.


> Off this list I was sent the AB servo best wiring practices pdf 
> which explained how to reduce noise in a servo drive enclosure. I 
> followed the advise as much as possible and after removing all my ground 
> wire antennas I was back running with an occasional sserial error. The 
> short explanation is to terminate the shields to a ground plane as close 
> as possible to the point where you take the shield/drain wire from the 
> cable. I still have a cable bundle running to my switch box that is 
> parallel wires and I might replace that with some twisted pairs. Photos 
> at 11.

You refer to this document?
http://literature.rockwellautomation.com/idc/groups/literature/documents/at/motion-at004_-en-p.pdf

That doc explains very well how to separate into different power zones.
Also, it makes a good case of shielding and how to do it properly. BTW,
note that it uses protective ground as shield potential and _not_ 0VDC.
That is also why the argument of two-sided termination of the shield is
appropriate (see page 21).

But all this does not save you from impedance problems. The sserial
errors are interesting because it is probably something you actually can
measure with an oscilloscope.

You should be able to see the signal integrity and whether you have
reflections of the signal at either end of the cable.

The sserial connection has a great potential for a loop. See attached
image for illustration. The image has a shielded connection between two
devices, which is good. However, the 0VDC connection (aka GND), which is
embedded in the shielded connection is shorted outside the cable via a
protective ground connection through the PSUs. This means that part of
the signal return may circumvent the constraints of the signal cable and
that creates an unbalanced path. Effectively, it means that the shield
is now part of the cable's impedance, and that is guaranteed to be off
by a factor.

You can check for this scenario by disconnecting the sserial connector
at one side and measure 0VDC vs protective ground on the connector on
the other side (and the other way around). You are in trouble when
measurements on both sides indicate a connection between 0VDC and
protective ground.

If you only have one PSU for both devices, then you are potentially also
in trouble. The PSU will then act as the loop facilitator (through two
distinct 0VDC connections). However, the effects are more subtle and
depend on coupling effects.

The rule for a shielded cable is that all energy must be contained
within the cable to be effective. In other words, the sum of all
currents in the cable's wires must be zero. Bypassing some of it may
cause impedance and therefore signal integrity problems.

-- 
Greetings Bertho

(disclaimers are disclaimed)
--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[Dave Cole]

Do you have filters just prior to the input power on the AB Servo drives?

I've also had problems with Teco servo drives backfeeding noise into the 
AC line and messing with Mesa boards.
An input filter from AD fixed that problem as well.

Dave

On 1/10/2016 6:44 AM, John Thornton wrote:
> Well none of the suggestions about star grounding did any good. In fact
> they made the problem worse than before, so bad I could not even get 2.6
> to run. Off this list I was sent the AB servo best wiring practices pdf
> which explained how to reduce noise in a servo drive enclosure. I
> followed the advise as much as possible and after removing all my ground
> wire antennas I was back running with an occasional sserial error. The
> short explanation is to terminate the shields to a ground plane as close
> as possible to the point where you take the shield/drain wire from the
> cable. I still have a cable bundle running to my switch box that is
> parallel wires and I might replace that with some twisted pairs. Photos
> at 11.
>
> JT
>
> --
> Site24x7 APM Insight: Get Deep Visibility into Application Performance
> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
> Monitor end-to-end web transactions and take corrective actions now
> Troubleshoot faster and improve end-user experience. Signup Now!
> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users

--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[Bertho Stultiens]

On 01/10/2016 02:48 PM, Bertho Stultiens wrote:
> The sserial connection has a great potential for a loop. See attached
> image for illustration. The image has a shielded connection between two
> devices, which is good. However, the 0VDC connection (aka GND), which is
> embedded in the shielded connection is shorted outside the cable via a
> protective ground connection through the PSUs. This means that part of
> the signal return may circumvent the constraints of the signal cable and
> that creates an unbalanced path. Effectively, it means that the shield
> is now part of the cable's impedance, and that is guaranteed to be off
> by a factor.

The sserial connection is a differential line (like rs422 afaik). See
for example http://focus.ti.com/lit/an/slla070d/slla070d.pdf chapter
4.5. Scenario 4.5.2 will get you into trouble in noisy environments.


-- 
Greetings Bertho

(disclaimers are disclaimed)

--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[John Thornton]

I don't have AB drives... I have a filter on my GS2 and another one 
after the control transformer.

JT

On 1/10/2016 11:40 AM, Dave Cole wrote:
> Do you have filters just prior to the input power on the AB Servo drives?
>
> I've also had problems with Teco servo drives backfeeding noise into the
> AC line and messing with Mesa boards.
> An input filter from AD fixed that problem as well.
>
> Dave
>
> On 1/10/2016 6:44 AM, John Thornton wrote:
>> Well none of the suggestions about star grounding did any good. In fact
>> they made the problem worse than before, so bad I could not even get 2.6
>> to run. Off this list I was sent the AB servo best wiring practices pdf
>> which explained how to reduce noise in a servo drive enclosure. I
>> followed the advise as much as possible and after removing all my ground
>> wire antennas I was back running with an occasional sserial error. The
>> short explanation is to terminate the shields to a ground plane as close
>> as possible to the point where you take the shield/drain wire from the
>> cable. I still have a cable bundle running to my switch box that is
>> parallel wires and I might replace that with some twisted pairs. Photos
>> at 11.
>>
>> JT
>>
>> --
>> Site24x7 APM Insight: Get Deep Visibility into Application Performance
>> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
>> Monitor end-to-end web transactions and take corrective actions now
>> Troubleshoot faster and improve end-user experience. Signup Now!
>> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
>> ___
>> Emc-users mailing list
>> Emc-users@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/emc-users
> --
> Site24x7 APM Insight: Get Deep Visibility into Application Performance
> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
> Monitor end-to-end web transactions and take corrective actions now
> Troubleshoot faster and improve end-user experience. Signup Now!
> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[Rafael]

I tried to find the original message in previous monster thread to have 
a better understanding of the problem but could not find it. I can't 
remember seeing what is connecting to VFD and few other things. I assume 
it's a Mesa board but which one? [1]

We all seem to keep running in circles here. Grounding had been 
mentioned many times, other theories abound, yet the system still shows 
"occasional sserial error". Occasional error is unlikely happening with 
good grounding solution unless you have a heavy load that pulls huge 
current through the ground exactly at that time or a high voltage spike 
somewhere.

In my last post in previous thread I suggested to go back to the 
beginning and check HW around the data line, both visual and electrical:
- cable, connectors including soldered or crimped connections,
- metal dust and corrosion on PCB traces, ICs, capacitors, (but I see 
your box is very clean)

I checked one of your pictures and see that you have a PC like power 
supply mounted on the door. PSU would be better mounted on the main 
panel, possibly eliminating need for undesirable DC cable extension. How 
good is the PSU?

Are the door and the box grounded to the common ground on the panel? 
Can't see that in the picture. I see wires at the bottom corners of the 
analog servo board, one black (left) and three black with yellow shrink 
tube (right). They are connected to the panel but not together in a star 
configuration. Where do they go? I don't see one (copper) bus bar for 
use as a common ground for everything.

More close up pictures from different angles would be helpful.

Additional questions related to "occasional sserial error" pop up in mind:
* what does it mean "occasional"? One error per 100 characters sent, one 
per 1k, etc.?
* what about parity or error correction?
* what kind of a command is issued when this happens?
* what happens before and after "sserial error" occurs?
* what are DC levels on serial connection?
* what is the noise level on DC power lines in idle mode and under the load?
* does it happen when the door is closed or open? See PSU notes above.
* is it always the same sequence of bits/bytes when this happens?
* what about mechanical vibration at the time?
* is it HW issue at all? What about the software? Are you doing 
something else on the same system while the CNC code is executing?
* Is there firmware in IO interface you need to deal with?
* where do you see "sserial error"? Log files or screen popup message? I 
think it's dmesg but I'm not familiar with this obviously. If log files 
what else is there before and after?

[1] http://www.linuxcnc.org/docs/devel/html/man/man9/sserial.9.html

On 01/10/2016 03:44 AM, John Thornton wrote:
> Well none of the suggestions about star grounding did any good. In fact
> they made the problem worse than before, so bad I could not even get 2.6
> to run. Off this list I was sent the AB servo best wiring practices pdf
> which explained how to reduce noise in a servo drive enclosure. I
> followed the advise as much as possible and after removing all my ground
> wire antennas I was back running with an occasional sserial error. The
> short explanation is to terminate the shields to a ground plane as close
> as possible to the point where you take the shield/drain wire from the
> cable. I still have a cable bundle running to my switch box that is
> parallel wires and I might replace that with some twisted pairs. Photos
> at 11.
>
> JT

Everybody please trim advertising and other noise at the bottom or other 
parts that are not relevant in the replies.

-- 
Rafael

--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[Dave Cole]

I understand.I'm working out of town and just came back for the 
weekend.

For me this is a good time to be distracted with too much work.

It helps me ignore the wind gusts to 30 mph, the snow, and the temps 
headed to 8 degrees F for tonight.
Except that I need to drive a long ways in this crap tomorrow morning.

Dave

On 1/10/2016 3:59 PM, John Thornton wrote:
> Still trying to digest this in between working...
>
> On 1/10/2016 7:48 AM, Bertho Stultiens wrote:
>> On 01/10/2016 12:44 PM, John Thornton wrote:
>>> Well none of the suggestions about star grounding did any good. In
>>> fact they made the problem worse than before, so bad I could not even
>>> get 2.6 to run.
>> That may suggest a couple of things being wrong simultaneously:
>> 1) you may still have loops in the 0VDC which are crossing power
>> domains. These /are/ hard to detect with many devices connected together;
>> 2) there are impedance mismatches in the signal wiring (this one often
>> works together with 1);
>> 3) shields may pick up noise they should reject.
>>
>> The question is how to reduce the practical problems, not how to
>> eliminate all theoretical problems. That is the hard part.
>>
>>
>>> Off this list I was sent the AB servo best wiring practices pdf
>>> which explained how to reduce noise in a servo drive enclosure. I
>>> followed the advise as much as possible and after removing all my ground
>>> wire antennas I was back running with an occasional sserial error. The
>>> short explanation is to terminate the shields to a ground plane as close
>>> as possible to the point where you take the shield/drain wire from the
>>> cable. I still have a cable bundle running to my switch box that is
>>> parallel wires and I might replace that with some twisted pairs. Photos
>>> at 11.
>> You refer to this document?
>> http://literature.rockwellautomation.com/idc/groups/literature/documents/at/motion-at004_-en-p.pdf
>>
>> That doc explains very well how to separate into different power zones.
>> Also, it makes a good case of shielding and how to do it properly. BTW,
>> note that it uses protective ground as shield potential and _not_ 0VDC.
>> That is also why the argument of two-sided termination of the shield is
>> appropriate (see page 21).
>>
>> But all this does not save you from impedance problems. The sserial
>> errors are interesting because it is probably something you actually can
>> measure with an oscilloscope.
>>
>> You should be able to see the signal integrity and whether you have
>> reflections of the signal at either end of the cable.
>>
>> The sserial connection has a great potential for a loop. See attached
>> image for illustration. The image has a shielded connection between two
>> devices, which is good. However, the 0VDC connection (aka GND), which is
>> embedded in the shielded connection is shorted outside the cable via a
>> protective ground connection through the PSUs. This means that part of
>> the signal return may circumvent the constraints of the signal cable and
>> that creates an unbalanced path. Effectively, it means that the shield
>> is now part of the cable's impedance, and that is guaranteed to be off
>> by a factor.
>>
>> You can check for this scenario by disconnecting the sserial connector
>> at one side and measure 0VDC vs protective ground on the connector on
>> the other side (and the other way around). You are in trouble when
>> measurements on both sides indicate a connection between 0VDC and
>> protective ground.
>>
>> If you only have one PSU for both devices, then you are potentially also
>> in trouble. The PSU will then act as the loop facilitator (through two
>> distinct 0VDC connections). However, the effects are more subtle and
>> depend on coupling effects.
>>
>> The rule for a shielded cable is that all energy must be contained
>> within the cable to be effective. In other words, the sum of all
>> currents in the cable's wires must be zero. Bypassing some of it may
>> cause impedance and therefore signal integrity problems.
>>
>>
>>
>> --
>> Site24x7 APM Insight: Get Deep Visibility into Application Performance
>> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
>> Monitor end-to-end web transactions and take corrective actions now
>> Troubleshoot faster and improve end-user experience. Signup Now!
>> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
>>
>>
>> ___
>> Emc-users mailing list
>> Emc-users@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/emc-users
> --
> Site24x7 APM Insight: Get Deep Visibility into Application Performance
> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
> Monitor end-to-end web transactions and take corrective actions now
> Troubleshoot faster and improve end-user experience. Signup Now!

Re: [Emc-users] Rewiring the BP Again

[Dave Cole]

My mistake, gotta clean my glasses apparently.

What are you using for axes drives?

Dave

On 1/10/2016 3:35 PM, John Thornton wrote:
> I don't have AB drives... I have a filter on my GS2 and another one
> after the control transformer.
>
> JT
>
> On 1/10/2016 11:40 AM, Dave Cole wrote:
>> Do you have filters just prior to the input power on the AB Servo drives?
>>
>> I've also had problems with Teco servo drives backfeeding noise into the
>> AC line and messing with Mesa boards.
>> An input filter from AD fixed that problem as well.
>>
>> Dave
>>
>> On 1/10/2016 6:44 AM, John Thornton wrote:
>>> Well none of the suggestions about star grounding did any good. In fact
>>> they made the problem worse than before, so bad I could not even get 2.6
>>> to run. Off this list I was sent the AB servo best wiring practices pdf
>>> which explained how to reduce noise in a servo drive enclosure. I
>>> followed the advise as much as possible and after removing all my ground
>>> wire antennas I was back running with an occasional sserial error. The
>>> short explanation is to terminate the shields to a ground plane as close
>>> as possible to the point where you take the shield/drain wire from the
>>> cable. I still have a cable bundle running to my switch box that is
>>> parallel wires and I might replace that with some twisted pairs. Photos
>>> at 11.
>>>
>>> JT
>>>
>>> --
>>> Site24x7 APM Insight: Get Deep Visibility into Application Performance
>>> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
>>> Monitor end-to-end web transactions and take corrective actions now
>>> Troubleshoot faster and improve end-user experience. Signup Now!
>>> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
>>> ___
>>> Emc-users mailing list
>>> Emc-users@lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/emc-users
>> --
>> Site24x7 APM Insight: Get Deep Visibility into Application Performance
>> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
>> Monitor end-to-end web transactions and take corrective actions now
>> Troubleshoot faster and improve end-user experience. Signup Now!
>> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
>> ___
>> Emc-users mailing list
>> Emc-users@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/emc-users
>
> --
> Site24x7 APM Insight: Get Deep Visibility into Application Performance
> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
> Monitor end-to-end web transactions and take corrective actions now
> Troubleshoot faster and improve end-user experience. Signup Now!
> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users

--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[John Thornton]

The original Anliam drives and power supply.

JT

On 1/10/2016 2:41 PM, Dave Cole wrote:
> My mistake, gotta clean my glasses apparently.
>
> What are you using for axes drives?
>
> Dave
>
> On 1/10/2016 3:35 PM, John Thornton wrote:
>> I don't have AB drives... I have a filter on my GS2 and another one
>> after the control transformer.
>>
>> JT
>>
>> On 1/10/2016 11:40 AM, Dave Cole wrote:
>>> Do you have filters just prior to the input power on the AB Servo drives?
>>>
>>> I've also had problems with Teco servo drives backfeeding noise into the
>>> AC line and messing with Mesa boards.
>>> An input filter from AD fixed that problem as well.
>>>
>>> Dave
>>>
>>> On 1/10/2016 6:44 AM, John Thornton wrote:
 Well none of the suggestions about star grounding did any good. In fact
 they made the problem worse than before, so bad I could not even get 2.6
 to run. Off this list I was sent the AB servo best wiring practices pdf
 which explained how to reduce noise in a servo drive enclosure. I
 followed the advise as much as possible and after removing all my ground
 wire antennas I was back running with an occasional sserial error. The
 short explanation is to terminate the shields to a ground plane as close
 as possible to the point where you take the shield/drain wire from the
 cable. I still have a cable bundle running to my switch box that is
 parallel wires and I might replace that with some twisted pairs. Photos
 at 11.

 JT

 --
 Site24x7 APM Insight: Get Deep Visibility into Application Performance
 APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
 Monitor end-to-end web transactions and take corrective actions now
 Troubleshoot faster and improve end-user experience. Signup Now!
 http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
 ___
 Emc-users mailing list
 Emc-users@lists.sourceforge.net
 https://lists.sourceforge.net/lists/listinfo/emc-users
>>> --
>>> Site24x7 APM Insight: Get Deep Visibility into Application Performance
>>> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
>>> Monitor end-to-end web transactions and take corrective actions now
>>> Troubleshoot faster and improve end-user experience. Signup Now!
>>> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
>>> ___
>>> Emc-users mailing list
>>> Emc-users@lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/emc-users
>> --
>> Site24x7 APM Insight: Get Deep Visibility into Application Performance
>> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
>> Monitor end-to-end web transactions and take corrective actions now
>> Troubleshoot faster and improve end-user experience. Signup Now!
>> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
>> ___
>> Emc-users mailing list
>> Emc-users@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/emc-users
> --
> Site24x7 APM Insight: Get Deep Visibility into Application Performance
> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
> Monitor end-to-end web transactions and take corrective actions now
> Troubleshoot faster and improve end-user experience. Signup Now!
> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[John Thornton]

Still trying to digest this in between working...

On 1/10/2016 7:48 AM, Bertho Stultiens wrote:
> On 01/10/2016 12:44 PM, John Thornton wrote:
>> Well none of the suggestions about star grounding did any good. In
>> fact they made the problem worse than before, so bad I could not even
>> get 2.6 to run.
> That may suggest a couple of things being wrong simultaneously:
> 1) you may still have loops in the 0VDC which are crossing power
> domains. These /are/ hard to detect with many devices connected together;
> 2) there are impedance mismatches in the signal wiring (this one often
> works together with 1);
> 3) shields may pick up noise they should reject.
>
> The question is how to reduce the practical problems, not how to
> eliminate all theoretical problems. That is the hard part.
>
>
>> Off this list I was sent the AB servo best wiring practices pdf
>> which explained how to reduce noise in a servo drive enclosure. I
>> followed the advise as much as possible and after removing all my ground
>> wire antennas I was back running with an occasional sserial error. The
>> short explanation is to terminate the shields to a ground plane as close
>> as possible to the point where you take the shield/drain wire from the
>> cable. I still have a cable bundle running to my switch box that is
>> parallel wires and I might replace that with some twisted pairs. Photos
>> at 11.
> You refer to this document?
> http://literature.rockwellautomation.com/idc/groups/literature/documents/at/motion-at004_-en-p.pdf
>
> That doc explains very well how to separate into different power zones.
> Also, it makes a good case of shielding and how to do it properly. BTW,
> note that it uses protective ground as shield potential and _not_ 0VDC.
> That is also why the argument of two-sided termination of the shield is
> appropriate (see page 21).
>
> But all this does not save you from impedance problems. The sserial
> errors are interesting because it is probably something you actually can
> measure with an oscilloscope.
>
> You should be able to see the signal integrity and whether you have
> reflections of the signal at either end of the cable.
>
> The sserial connection has a great potential for a loop. See attached
> image for illustration. The image has a shielded connection between two
> devices, which is good. However, the 0VDC connection (aka GND), which is
> embedded in the shielded connection is shorted outside the cable via a
> protective ground connection through the PSUs. This means that part of
> the signal return may circumvent the constraints of the signal cable and
> that creates an unbalanced path. Effectively, it means that the shield
> is now part of the cable's impedance, and that is guaranteed to be off
> by a factor.
>
> You can check for this scenario by disconnecting the sserial connector
> at one side and measure 0VDC vs protective ground on the connector on
> the other side (and the other way around). You are in trouble when
> measurements on both sides indicate a connection between 0VDC and
> protective ground.
>
> If you only have one PSU for both devices, then you are potentially also
> in trouble. The PSU will then act as the loop facilitator (through two
> distinct 0VDC connections). However, the effects are more subtle and
> depend on coupling effects.
>
> The rule for a shielded cable is that all energy must be contained
> within the cable to be effective. In other words, the sum of all
> currents in the cable's wires must be zero. Bypassing some of it may
> cause impedance and therefore signal integrity problems.
>
>
>
> --
> Site24x7 APM Insight: Get Deep Visibility into Application Performance
> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
> Monitor end-to-end web transactions and take corrective actions now
> Troubleshoot faster and improve end-user experience. Signup Now!
> http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users

--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP Again

[Dave Cole]

Hmm.. perhaps you should tell Peter that Missouri is wonderful this time 
of year.

Perhaps he will schedule a flight to the "show me state".  :-)

Dave

On 1/10/2016 3:35 PM, John Thornton wrote:
> I don't have AB drives... I have a filter on my GS2 and another one
> after the control transformer.
>
> JT
>
>

--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Dave Cole]

Just saw your message.

If you keep the VFD powered off, do you still have noise issues ??

Dave

On 1/4/2016 5:19 PM, John Thornton wrote:
> I have 3 DC power supplies in the drive side, a 5vdc, a 24vdc, and a
> 170vdc.
>
> The 5vdc power supply on the 0v side reads 37.6 ohms with the 0v and 5v
> sides connected to the 7i77 5v plug. The 7i77 is the only thing it
> powers up. When I unplug the 7i77 0v reads open so there is a path
> through the 7i77 5v to ground.
>
> The 24vdc power supply is for the limit switches and push buttons. It
> reads open from 0v to ground.
>
> The 170vdc power supply is a bridge rectifier with a large blue cap and
> a power resistor. See the photo in the link of the current panel. I
> can't tell which side should be 0v but both sides measure 0.65M ohms to
> ground. I don't know if that is reading back through the bridge
> rectifier or the drives. It only powers the three axis drives.
>
> Current panel layout http://gnipsel.com/images/bp-knee-mill/bpel06.jpg
>
> JT
>
> On 1/4/2016 10:48 AM, Bertho Stultiens wrote:
>> On 01/04/2016 05:34 PM, John Thornton wrote:
>>> Well I grounded X2 to the main ground and when I started LinuxCNC and
>>> started to home I got the flurry of sserial errors. So I thought about
>>> it for a bit and maybe the ground from the computer case to the ground
>>> block was creating a ground loop so I took it off. Started LinuxCNC and
>>> immediately go a flurry of sserial errors which locks up LinuxCNC. Mind
>>> you this is with the 7i77ISOL card between the 5i25 and the 7i77 which
>>> is supposed to block any noise in the sserial communications. The X2 to
>>> ground has to go...
>>>
>>> I do have a 7i92 to test out...
>> My guess is that you have more than one (ground-)loop. You also need to
>> check how the 0V (DC) line interacts with other devices/converters etc.
>> wrt. ground and see whether any of them also hook-up to ground somewhere
>> along the wiring, PCBs or supplies.
>>
>> The second type of loops can be (entirely) in the 0V (DC) connection(s)
>> where multiple paths, with different impedances, impair the integrity of
>> the signal lines. You need to check how the different DC supplies
>> interact with the connections as they are. The problem often becomes
>> visible when you have both high- and low-power devices connecting and
>> running on the same supply and have the 0V (DC) connected so that it
>> (can) create(s) a loop.
>>
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users

--
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=267308311=/4140
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 01/04/2016 07:34 PM, Mark Johnsen wrote:
> Bertho - What you state about the different power supplies is a fear of
> mine as I have a +-15vdc Power supply for the Op-amps for the West-Amp
> servos, an open frame type 24Vdc power supply, plus the 5vdc power supply I
> added for the 7i77.

Many PSUs just makes it harder and the chances of "doing it wrong" a lot
larger as well as inadvertent (read: potentially disastrous) things
happen when you start to fiddle in the wiring to test one or another
thing...


> Also, I don't have my PC in a PC case, open frame w/ the 5i25 held in by
> friction (i know, I don't like this either -  need to bend a clamp).  But,
> the PC power supply also could factor into the ground loop equation.  I
> have mine mounted to the door of my enclosure.

The PC PSU is almost certainly connecting 0V (DC) to the protective
ground. That almost(*) always means that all other supplies need to be
isolated from protective ground, or you will have a loop.

Anyhow, all the PSUs make it a nightmare to track the 0V (DC) reference
throughout and ensuring it cannot loop. Especially low-power (signal)
connections are hurting badly if you loop it with a high-power (DC)
circuits.


(*) There are some narrow exceptions (ymmv), but don't bet your sanity
on that.



> I feel like it's really hard to trouble shoot because you have the 5vdc to
> power the 7i77 and then limits, relays, etc are presumably run off 24vdc.
> So, plenty of ground loop possibilities, especially w/ the encoders and
> limits being wired up on the original wiring.  Plus the addition of the PC
> to the cabinet...

You hit dead center here... It is a nightmare to troubleshoot. That is
why you usually need to plan very carefully in advance (yeah, I know,
good idea, but time is scarce).

A few design guidelines:
1) keep high-power and low-power systems separated as good as possible
(both AC- and DC-wise);
2) assure, in the low-power system, that you separate the
high-speed-signal and the low-speed-signal parts as much as possible;
3) design using a star-shape. One center and from there to the
peripherals. Interconnects on different star-legs usually/often need to
be galvanically isolated to prevent loops.
4) test incrementally. It is much easier to identify the problem when it
is detected when one (1) single and simple device is added. (However the
cause can still be extremely complex due to interactions.)


-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Rafael]

  When nothing else works, it's wise to go back to the beginning. After 
so many suggestions, recommendations, and disagreements we have not 
solved this problem since last year.

While grounding could be a major issue, it's not necessarily so in this 
case. As long as there is star wired ground. Besides ground loops don't 
always add up, sometimes they subtract too. Of course, we are not at the 
broken system so troubleshooting is obviously difficult.

On 12/26/2015 07:16 AM, John Thornton wrote:
> I just checked the ground to housing on the VFD filter, VFD, computer,
> and the smaller filter and they are all internally connected to ground.
> The VFD is controlled via modbus so I don't know how to check that cable
> (which is just a phone cable with a phone jack on one end and a DB9 on
> the other end to connect to the computers serial port, it's a Automation
> Direct cable not home made.
>
> Is injection to the mains coming back to the machine somehow?
>
> JT

Troubleshooting was mostly focused on ground and wiring so far. Modbus 
is where the (noisy) action is so it's the most obvious place to start 
troubleshooting.

Not being familiar with modbus I decided to do some reading on it.
https://en.wikipedia.org/wiki/Modbus
https://en.wikipedia.org/wiki/RS-232

If I understand it correctly, there are 3 physical means to carry 
modbus: RS-232, RS-485, and ethernet. RS stands for Recommended 
Standard, which never became a real standard as far as I'm concerned. 
I've seen RS-232 implementations for mainframe and PC computer 
peripherals and ham radio ranging from ±25V to ±12V and what's most 
common today, ±5V.

RS-232 is relatively immune to noise, for speeds we are dealing with 
here, as long as one side of shielded cable is grounded. We used to have 
cable runs between mainframe computers and terminals in other buildings 
with (to a degree) different ground and no major issues.

After some search, I ended up reading this document, Modbus For Field 
Technicians:
http://www.modbusbacnet.com/includes/pdf/MODBUS_2010Nov12.pdf
see pages 29 and numerous pages dedicated to RS-485 issues.

I am assuming that your implementation is based on either RS-232 or 
RS-485. At this point it might be worthwhile to look into VFD "black 
box" to see how exactly it connects to the outside world.

Time to check:
- (HW) drivers, ICs, transistors, local caps, voltages [1],
- configuration (parity, etc.),
- use RS-232 breakbox and check signals quality with scope
- try different RS-232 port on PC or replace it if necessary.
- any related jumpers, if any

[1] optical connection protects you from different voltage levels but 
that was not your first try I think so the port on PC side could be 
damaged if the VFD side uses 12V for example. It depends on how old the 
VFD is.

Unknown:
- was VFD/modbus fully functional before rewiring BP?
- What says the VFD maintenance manual?
- Can you run standalone tests on VFD?

How about replacing the DC motors with large resistors and run the 
tests? One by one or all. Are those brushless motors? What's the noise 
around motor wires with a motor or with a resistor?

-- 
Rafael

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

I have 3 DC power supplies in the drive side, a 5vdc, a 24vdc, and a 
170vdc.

The 5vdc power supply on the 0v side reads 37.6 ohms with the 0v and 5v 
sides connected to the 7i77 5v plug. The 7i77 is the only thing it 
powers up. When I unplug the 7i77 0v reads open so there is a path 
through the 7i77 5v to ground.

The 24vdc power supply is for the limit switches and push buttons. It 
reads open from 0v to ground.

The 170vdc power supply is a bridge rectifier with a large blue cap and 
a power resistor. See the photo in the link of the current panel. I 
can't tell which side should be 0v but both sides measure 0.65M ohms to 
ground. I don't know if that is reading back through the bridge 
rectifier or the drives. It only powers the three axis drives.

Current panel layout http://gnipsel.com/images/bp-knee-mill/bpel06.jpg

JT

On 1/4/2016 10:48 AM, Bertho Stultiens wrote:
> On 01/04/2016 05:34 PM, John Thornton wrote:
>> Well I grounded X2 to the main ground and when I started LinuxCNC and
>> started to home I got the flurry of sserial errors. So I thought about
>> it for a bit and maybe the ground from the computer case to the ground
>> block was creating a ground loop so I took it off. Started LinuxCNC and
>> immediately go a flurry of sserial errors which locks up LinuxCNC. Mind
>> you this is with the 7i77ISOL card between the 5i25 and the 7i77 which
>> is supposed to block any noise in the sserial communications. The X2 to
>> ground has to go...
>>
>> I do have a 7i92 to test out...
> My guess is that you have more than one (ground-)loop. You also need to
> check how the 0V (DC) line interacts with other devices/converters etc.
> wrt. ground and see whether any of them also hook-up to ground somewhere
> along the wiring, PCBs or supplies.
>
> The second type of loops can be (entirely) in the 0V (DC) connection(s)
> where multiple paths, with different impedances, impair the integrity of
> the signal lines. You need to check how the different DC supplies
> interact with the connections as they are. The problem often becomes
> visible when you have both high- and low-power devices connecting and
> running on the same supply and have the 0V (DC) connected so that it
> (can) create(s) a loop.
>


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 01/04/2016 05:34 PM, John Thornton wrote:
> Well I grounded X2 to the main ground and when I started LinuxCNC and 
> started to home I got the flurry of sserial errors. So I thought about 
> it for a bit and maybe the ground from the computer case to the ground 
> block was creating a ground loop so I took it off. Started LinuxCNC and 
> immediately go a flurry of sserial errors which locks up LinuxCNC. Mind 
> you this is with the 7i77ISOL card between the 5i25 and the 7i77 which 
> is supposed to block any noise in the sserial communications. The X2 to 
> ground has to go...
> 
> I do have a 7i92 to test out...

My guess is that you have more than one (ground-)loop. You also need to
check how the 0V (DC) line interacts with other devices/converters etc.
wrt. ground and see whether any of them also hook-up to ground somewhere
along the wiring, PCBs or supplies.

The second type of loops can be (entirely) in the 0V (DC) connection(s)
where multiple paths, with different impedances, impair the integrity of
the signal lines. You need to check how the different DC supplies
interact with the connections as they are. The problem often becomes
visible when you have both high- and low-power devices connecting and
running on the same supply and have the 0V (DC) connected so that it
(can) create(s) a loop.

-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

Well I grounded X2 to the main ground and when I started LinuxCNC and 
started to home I got the flurry of sserial errors. So I thought about 
it for a bit and maybe the ground from the computer case to the ground 
block was creating a ground loop so I took it off. Started LinuxCNC and 
immediately go a flurry of sserial errors which locks up LinuxCNC. Mind 
you this is with the 7i77ISOL card between the 5i25 and the 7i77 which 
is supposed to block any noise in the sserial communications. The X2 to 
ground has to go...

I do have a 7i92 to test out...

JT

On 1/2/2016 6:26 AM, John Thornton wrote:
> I do have a "control transformer" which can be identified by the three 
> fuses on top. One for X1 (secondary) and one each for L1 and L2. I 
> went back and found out which was X1 and X2 and will correct my wiring 
> today. My question is I have a filter on X1 and X2 should I ground 
> before or after the filter?
>
> JT
>
> On 1/1/2016 6:41 PM, John Kasunich wrote:
>> 120V transformer secondaries (in the USA) need to be grounded on
>> one side, even if they are part of a machine control panel.
>>
>> Such transformers are referred to as "control power transformers"
>> and traditionally powered electro-mechanical control devices such
>> as relays and contactors.  Today they still power those things, and
>> they also power AC-to-DC supplies that run the electronic parts of
>> the control.The low voltage DC power distribution (typically 24V)
>> is sometimes un-grounded, sometimes single-point grounded, for
>> exactly the noise reasons Berthos mentions.  But the 120V "control
>> power" isn't used a the "reference" for anything - it is still "dirty"
>> power, although not as dirty as the main power that might be going
>> to a VFD or whatever.
>
>
>
> --
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

What it boils down to is not the VFD but something in the DC or low 
voltage circuits. I don't have a modbus problem but rather a sserial 
problem.

Thanks

On 1/4/2016 3:00 PM, Rafael wrote:
>When nothing else works, it's wise to go back to the beginning. After
> so many suggestions, recommendations, and disagreements we have not
> solved this problem since last year.
>
> While grounding could be a major issue, it's not necessarily so in this
> case. As long as there is star wired ground. Besides ground loops don't
> always add up, sometimes they subtract too. Of course, we are not at the
> broken system so troubleshooting is obviously difficult.
>
> On 12/26/2015 07:16 AM, John Thornton wrote:
>> I just checked the ground to housing on the VFD filter, VFD, computer,
>> and the smaller filter and they are all internally connected to ground.
>> The VFD is controlled via modbus so I don't know how to check that cable
>> (which is just a phone cable with a phone jack on one end and a DB9 on
>> the other end to connect to the computers serial port, it's a Automation
>> Direct cable not home made.
>>
>> Is injection to the mains coming back to the machine somehow?
>>
>> JT
> Troubleshooting was mostly focused on ground and wiring so far. Modbus
> is where the (noisy) action is so it's the most obvious place to start
> troubleshooting.
>
> Not being familiar with modbus I decided to do some reading on it.
> https://en.wikipedia.org/wiki/Modbus
> https://en.wikipedia.org/wiki/RS-232
>
> If I understand it correctly, there are 3 physical means to carry
> modbus: RS-232, RS-485, and ethernet. RS stands for Recommended
> Standard, which never became a real standard as far as I'm concerned.
> I've seen RS-232 implementations for mainframe and PC computer
> peripherals and ham radio ranging from ±25V to ±12V and what's most
> common today, ±5V.
>
> RS-232 is relatively immune to noise, for speeds we are dealing with
> here, as long as one side of shielded cable is grounded. We used to have
> cable runs between mainframe computers and terminals in other buildings
> with (to a degree) different ground and no major issues.
>
> After some search, I ended up reading this document, Modbus For Field
> Technicians:
> http://www.modbusbacnet.com/includes/pdf/MODBUS_2010Nov12.pdf
> see pages 29 and numerous pages dedicated to RS-485 issues.
>
> I am assuming that your implementation is based on either RS-232 or
> RS-485. At this point it might be worthwhile to look into VFD "black
> box" to see how exactly it connects to the outside world.
>
> Time to check:
> - (HW) drivers, ICs, transistors, local caps, voltages [1],
> - configuration (parity, etc.),
> - use RS-232 breakbox and check signals quality with scope
> - try different RS-232 port on PC or replace it if necessary.
> - any related jumpers, if any
>
> [1] optical connection protects you from different voltage levels but
> that was not your first try I think so the port on PC side could be
> damaged if the VFD side uses 12V for example. It depends on how old the
> VFD is.
>
> Unknown:
> - was VFD/modbus fully functional before rewiring BP?
> - What says the VFD maintenance manual?
> - Can you run standalone tests on VFD?
>
> How about replacing the DC motors with large resistors and run the
> tests? One by one or all. Are those brushless motors? What's the noise
> around motor wires with a motor or with a resistor?
>


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP - where to connect ground

[Ben Potter]

> From: Gene Heskett [mailto:ghesk...@wdtv.com] 
>>
>> Going really OT here (and I should probably start a new thread for
>> this) - what beyond a 1:1 ratio makes a transformer an 'isolation'
>> transformer.
>>
>No ohmic connection between primary and secondary.  If there is, and its
not just a carbon track from a lightning strike, its an autoformer, and
potentially a killer because it doesn't isolate.  Two pieces of wire are
exactly equal >to a 1/1 autoformer IOW..

Tested with my multimeter - can't measure a resistance between primary and
secondary.
Can't test further without borrowing a Megger.

Probably suitable for what I'm using it for.

Ta
Ben


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

I do have a "control transformer" which can be identified by the three 
fuses on top. One for X1 (secondary) and one each for L1 and L2. I went 
back and found out which was X1 and X2 and will correct my wiring today. 
My question is I have a filter on X1 and X2 should I ground before or 
after the filter?


JT

On 1/1/2016 6:41 PM, John Kasunich wrote:

120V transformer secondaries (in the USA) need to be grounded on
one side, even if they are part of a machine control panel.

Such transformers are referred to as "control power transformers"
and traditionally powered electro-mechanical control devices such
as relays and contactors.  Today they still power those things, and
they also power AC-to-DC supplies that run the electronic parts of
the control.The low voltage DC power distribution (typically 24V)
is sometimes un-grounded, sometimes single-point grounded, for
exactly the noise reasons Berthos mentions.  But the 120V "control
power" isn't used a the "reference" for anything - it is still "dirty"
power, although not as dirty as the main power that might be going
to a VFD or whatever.


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP - where to connect ground

[Gene Heskett]

On Saturday 02 January 2016 05:52:55 Ben Potter wrote:

> > From: Gene Heskett [mailto:ghesk...@wdtv.com]
> >
> >> Going really OT here (and I should probably start a new thread for
> >> this) - what beyond a 1:1 ratio makes a transformer an 'isolation'
> >> transformer.
> >
> >No ohmic connection between primary and secondary.  If there is, and
> > its
>
> not just a carbon track from a lightning strike, its an autoformer,
> and potentially a killer because it doesn't isolate.  Two pieces of
> wire are exactly equal >to a 1/1 autoformer IOW..
>
> Tested with my multimeter - can't measure a resistance between primary
> and secondary.
> Can't test further without borrowing a Megger.
>
> Probably suitable for what I'm using it for.
>
> Ta
> Ben
>
As long as its capacity is up to the job, yes.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Gene Heskett]

On Saturday 02 January 2016 07:26:08 John Thornton wrote:

> I do have a "control transformer" which can be identified by the three
> fuses on top. One for X1 (secondary) and one each for L1 and L2. I
> went back and found out which was X1 and X2 and will correct my wiring
> today. My question is I have a filter on X1 and X2 should I ground
> before or after the filter?
>
> JT
>
Thats a hard call John.  I think I'd get out the scope & see which gave 
you the best noise rejection.  To get rid of ground loops because the 
scope has a 3rd pin power plug, I'd power it from the transformer. But 
that would also make the ground after the obvious choice. YMMV of 
course.

> On 1/1/2016 6:41 PM, John Kasunich wrote:
> > 120V transformer secondaries (in the USA) need to be grounded on
> > one side, even if they are part of a machine control panel.
> >
> > Such transformers are referred to as "control power transformers"
> > and traditionally powered electro-mechanical control devices such
> > as relays and contactors.  Today they still power those things, and
> > they also power AC-to-DC supplies that run the electronic parts of
> > the control.The low voltage DC power distribution (typically
> > 24V) is sometimes un-grounded, sometimes single-point grounded, for
> > exactly the noise reasons Berthos mentions.  But the 120V "control
> > power" isn't used a the "reference" for anything - it is still
> > "dirty" power, although not as dirty as the main power that might be
> > going to a VFD or whatever.


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

It is a common practice to send out two hots and one neutral provided 
the two hots are not on the same phase. This is a copper saving thing

On 1/1/2016 7:34 PM, John Dammeyer wrote:
> Isn't it commonly called Split Phase in North America?
>
> Draw 15A on each side of the 120-0-120 VAC circuit and measure that with a
> clamp on ammeter and you get 15A on each leg.  Put the clamp on meter on the
> white wire (the neutral return)  and you get 0A. In effect the two phases
> are 180 degrees out of phase.  If it weren't so you'd have to make the white
> neutral wire handle twice the current of the black (and/or  red) hot wires.
>
> John Dammeyer
>
>
>> In the USA, Kirk is 100% correct.  Two phase means 90 degree phase
>> shift, and is pretty much non-existent.  120V-0V-120V with 240V from
>> end to end is "single phase".  Call it two-phase and people in the States
>> will look at you funny.
>>
>> John Kasunich
>>
>>
>>
>>
> 
> --
>> ___
>> Emc-users mailing list
>> Emc-users@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/emc-users
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Dammeyer]

Hi John,
To me it still looks like you have the 120VAC side of the transformer
totally isolated from frame ground.  

As John Kasunich has also stated it's incredibly dangerous to have that
120VAC voltage floating.  One side of the transformer should be immediately
connected to Earth (Frame) right out of the transformer before any filters.
With a ring terminal to a double nutted stud.  That same connection inside
your cabinet becomes the white wire and the green wire.  The other the Black
wire.  Connecting to your AC outlets is done with the black wire going to
the darker bronze screw which is the narrower blade and the white wire goes
to the nickle or light coloured screw and the wider blade.  The green which
is the protective ground goes to the ground terminal of the outlet.  It is
not good practice to connect the outlet ground pin to some other location.
Certainly not to Earth unless one side of your AC is also connected to
Earth.

As you have it in your drawing the ground provides absolutely no protection
in your circuit.

If you wish to filter noise out of the 120VAC side it's always best to do it
at the source of the noise, so the devices creating the electrical
interference  don't have the cabling to use as an antenna.  A noise filter
on the output of the transformer doesn't really make any sense to me.

Perhaps think of it this way.   Current always flows from source to
destination and back.  There has to be a complete circuit.  This is true for
power wiring and it's true for electrical noise.  

John Dammeyer


> -Original Message-
> From: John Thornton [mailto:j...@gnipsel.com]
> Sent: January-02-16 4:26 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] Rewiring the BP
> 
> I do have a "control transformer" which can be identified by the three
> fuses on top. One for X1 (secondary) and one each for L1 and L2. I went
> back and found out which was X1 and X2 and will correct my wiring today.
> My question is I have a filter on X1 and X2 should I ground before or
> after the filter?
> 
> JT
> 
> On 1/1/2016 6:41 PM, John Kasunich wrote:
> > 120V transformer secondaries (in the USA) need to be grounded on
> > one side, even if they are part of a machine control panel.
> >
> > Such transformers are referred to as "control power transformers"
> > and traditionally powered electro-mechanical control devices such
> > as relays and contactors.  Today they still power those things, and
> > they also power AC-to-DC supplies that run the electronic parts of
> > the control.The low voltage DC power distribution (typically 24V)
> > is sometimes un-grounded, sometimes single-point grounded, for
> > exactly the noise reasons Berthos mentions.  But the 120V "control
> > power" isn't used a the "reference" for anything - it is still "dirty"
> > power, although not as dirty as the main power that might be going
> > to a VFD or whatever.



--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Dave Cole]

Before it.   Literally run a green wire from the X2 terminal to the  
single point ground or to the steel backplane assuming you have one.

The protective fuse on X1 should be prior to the filter also.

Dave



On 1/2/2016 7:26 AM, John Thornton wrote:
> I do have a "control transformer" which can be identified by the three 
> fuses on top. One for X1 (secondary) and one each for L1 and L2. I 
> went back and found out which was X1 and X2 and will correct my wiring 
> today. My question is I have a filter on X1 and X2 should I ground 
> before or after the filter?
>
> JT
>
> On 1/1/2016 6:41 PM, John Kasunich wrote:
>> 120V transformer secondaries (in the USA) need to be grounded on
>> one side, even if they are part of a machine control panel.
>>
>> Such transformers are referred to as "control power transformers"
>> and traditionally powered electro-mechanical control devices such
>> as relays and contactors.  Today they still power those things, and
>> they also power AC-to-DC supplies that run the electronic parts of
>> the control.The low voltage DC power distribution (typically 24V)
>> is sometimes un-grounded, sometimes single-point grounded, for
>> exactly the noise reasons Berthos mentions.  But the 120V "control
>> power" isn't used a the "reference" for anything - it is still "dirty"
>> power, although not as dirty as the main power that might be going
>> to a VFD or whatever.
>
>
>
> --
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Dave Cole]

>>None of those seem to have an earthing spike _and_ a neutral to GND link.

The top of page 20 shows something very similar to how houses are wired 
in the US (except that we have two hot wires running into the houses, 
whereas the diagram shows one)
However it appears that the utility supplies the spiked earth safety 
ground rather than relying on the consumer to have proper wiring in the 
house (might be a better idea!)  Not the jumper (labled Link)  between 
the safety ground (PE) and the Neutral. It appears that is done just 
outside the house ??

In my house (very typical for rural houses in the US) I have a pole 
outside with a transformer on it that creates 240 volts with a center 
tap.(I have three phase voltage at 10,000+ volts running down our 
road on top of the poles.  It feeds the entire northern part of our 
county, I was told.A high voltage substation is down the road that 
drops it from transmission line voltage to the distribution voltage for 
the county.  )

The center tap is grounded via a bare copper conductor wire that runs 
down the pole into the ground.

A two conductor alum cable - heavy 2/0 (I think), with a stranded 
conductor that is wrapped around the cable  (They call it armored), and 
with a heavy plastic jacket on top of that runs underground to my 
basement where it enters a breaker box.   There the stranded outer 
conductor is tied to the neutral buss bar and the two hot lines run into 
the main breaker.A stranded grounding conductor runs from the 
neutral buss bar to a water pipe or ground rod (its hidden from view).

20+ breakers distribute power, either 240 (line to line) or 120 (line to 
neutral) throughout the house.

My house is all electric.

Dave



On 1/1/2016 6:43 PM, andy pugh wrote:
> On 27 December 2015 at 00:32, John Kasunich  wrote:
>> Each house has a ground rod.  The neutral from the transformer, the
>> house ground rod, a connection from the house cold water plumbing (if
>> copper), the neutrals from all the receptacles, and the ground wires from
>> all the receptacles are all tied together at a large bus bar in the main 
>> panel.
>
> Something of a digression, but this document describes the earthing
> systems legal for use in the UK
> http://electrical.theiet.org/wiring-matters/16/earthing-questions.cfm
>
> None of those seem to have an earthing spike _and_ a neutral to GND link.
>

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Dave Cole]

Yes.

And generally (old school US machine wiring) the hot (fused) leg for 120 
VAC control wiring is red and the neutral is white, especially if there 
are higher voltages in the same cabinet (like 480).   Then red is 120 AC 
control, white is Neutral, black is 240 or 480 AC power, Blue is DC etc.

Dave



On 1/1/2016 12:03 PM, John Thornton wrote:
> I just looked at the control transformer and L1 and L2 (240v side are
> fused with type CC fuses and X1 only on the 120v side is fused with a
> slo-blow fuse. So I assume they intended X2 to be the "neutral".
>
> JT
>
> On 1/1/2016 10:15 AM, Gene Heskett wrote:
>> On Friday 01 January 2016 07:00:31 John Thornton wrote:
>>
>>> Hi Gene,
>>>
>>> The frame is most solidly grounded. I'll do the tests in a bit. Keep
>>> in mind that I have a 240v to 120v step down transformer to supply the
>>> 120v not a normal house circuit. Again an effort to kill the noise.
>>> Which by the way I'm running 2.7 now after changing the wires on the
>>> limit/home switches to twisted pair shielded wire. I've attached the
>>> VFD side wiring diagram. I assume the connection is through the
>>> neutral bonding screw at the panel because the step down transformer
>>> is isolated from ground.
>>>
>>> Happy New Year to you too.
>>>
>>> JT
>> So this then was my 2nd guess, is the capacitative interwinding coupling
>> in that transformer capable of supplying a very few microamps of actual
>> current, probably less than 1 or 2. With no loads plugged in, you could
>> connect either of the output phases of that transformer to machine
>> frame "ground" without any fireworks which would bring the other up to
>> 127 to "ground".
>>
>> I believe in that case I would synthesize a std 127 volt circuit out of
>> the control transformers secondary by connecting the lower voltage wire
>> to the machines frame, along with the static ground wire in a short bit
>> of romex & using the std color code where the black wire is the high
>> side of the transformers secondary, feed it to a duplex or 4 plex to
>> power the computer, monitor, and any other 120 volt only loads on the
>> machine as long as the total load is within the ratings of the
>> transformer.
>>
>> That should be 100% safe for everything.  And it should reduce the
>> coupled noise just because its all bouncing in unison.
>>
>> Some of the noise coupling is coming into the 120 volt circuit from
>> the "longitudinal" coupling of the windings un-avoidable capacitance,
>> and grounding one side of it, and the loads static ground to the
>> machines frame & ground should absorb a good share of it.
>>
>> In really obnoxious cases, a small, perhaps a .01 to .1 uF capacitor
>> rated at least at 600 volts from the high side, black wire to the
>> duplex, to the machines frame should gobble up the rest of it. And not
>> just for S, I'd fuse the hot lead of that cap since a failure would
>> take out the control transformer.  Fused at less than the transformer is
>> rated of course since you want to blow the fuse instead of the
>> transformer.
>>
>> That was my theory when I hooked this room up, and I have not lost a
>> piece of gear during an electrical storm in over 10 years since I did
>> it.  With the 50kw can that supplies 4 houses on the pole across the
>> street, that pole has been nailed quite a few times, and I even got a
>> grab the doorknob shock that jumped out of a wired keyboard once.  So I
>> know this whole room full of electronics has bounced at least 25Kv. Not
>> even a computer crash when it happened.
>>
>> Electrical shock is a weirdly defined thing. Below 20 micro-amps directly
>> thru the heart, a currant so low you may not even feel it, is generally
>> harmless, but at 20 micro-amps up to about 20 milli-amps it can disturb
>> the beat, causing fibrillation and eventual death if no one removes the
>> power or you from the source and applies the defibber paddles.
>>
>> Above 20 milli-amps, the survival rate is better because the heart is
>> frozen, and when the currant is removed, and it hasn't been frozen so
>> long you are brain dead from lack of oxygen, then the heart will often
>> start back as if nothing has happened.
>>
>> Your trivia factoid for the day. :)
>>
>> My ex had a cousin that I met once in the 1970's after he had stuck an
>> alu ladder he was carrying into a low hanging 7200 volt line. Lost part
>> of a foot, and the shoulder blade and arm the ladder was laying on.
>> Never was the sharpest tack in the box, but I'd have guessed him at an
>> IQ of 105 to 110 or so after the event.  Some surgery, a specially built
>> boot and a while to heal, which he was still doing when I met him at
>> some sort of a family doin's, but by now he's probably taken over the
>> painting business his father started 50+ years ago and run it, if not
>> retired from it. That was a "few" thousand  days ago. :)  The ex left 31
>> years ago, ending any excuse I had to keep track of someone in Wisconsin
>> I only met once.
>>
>>> On 12/31/2015 

Re: [Emc-users] Rewiring the BP

[John Kasunich]

This is one of those cases where electrical practices on opposite
sides of oceans differ significantly.

On Fri, Jan 1, 2016, at 12:29 PM, Bertho Stultiens wrote:
> On 01/01/2016 05:47 PM, Dave Cole wrote:
> > That's done all of the time.   In fact it is part of the NEC (National 
> > Electric Code) that is followed (for the most part) in the US.
> > Pretty much every house in the US is wired like that.  (I'm not making 
> > this stuff up.  :-) )
> 
> I agree with the connection at power entry in the house. That is quite a
> different story. That is actually the same here in EU (most countries).
> 
> I think that we should separate two things:
> - house installation
> - machine wiring
> 
> House installation is pretty much standardized with a lot of rules and
> reasons. Specifically to ensure referencing and protection.
> 
> Machine wiring is different in that you can have scenarios where
> references are moved, especially in a 2-phase system where you are not
> using the neutral, which is the scenario we have here.

120V transformer secondaries (in the USA) need to be grounded on
one side, even if they are part of a machine control panel.

Such transformers are referred to as "control power transformers"
and traditionally powered electro-mechanical control devices such
as relays and contactors.  Today they still power those things, and
they also power AC-to-DC supplies that run the electronic parts of
the control.The low voltage DC power distribution (typically 24V)
is sometimes un-grounded, sometimes single-point grounded, for 
exactly the noise reasons Berthos mentions.  But the 120V "control
power" isn't used a the "reference" for anything - it is still "dirty"
power, although not as dirty as the main power that might be going
to a VFD or whatever.

The main reason for grounding one side of the 120V control power
circuit is for safety in the event of a primary-to-secondary
transformer insulation breakdown.  Machines in the US are powered
by anything from 240V single phase to 480V three phase.  An insulation
failure in the transformer could put up to 480V on the control circuits if 
the secondary was ungrounded.   With a grounded, secondary, it will
simply blow the transformer primary fuse(s), which are already rated
for the full primary voltage.

Control circuit fuses, wiring, pushbuttons etc, etc, are typically rated
150, 250, or 300V.  Not 480V.  So all kinds of bad things could happen
if 480V wound up on ungrounded control circuits.

Another reason for grounding one side is that you have a distinct
hot and neutral.  Hot is protected by fuses or breakers, neutral is not.
A typical industrial panel might have a half-dozen small single-pole
breakers or fuses feeding multiple low power loads.  If ungrounded,
those would all have to be two-pole devices.

> The reason for /not/ connecting the ground on a secondary winding is to
> prevent a capacitively coupled ground path. Especially if you cannot
> guarantee a 100% balanced primary-to-secondary side wrt. ground (*).
> 
> What happens is that there will be a current in the ground connection
> which causes an imbalanced current on the primary side (remember:
> primary is 2-phase circuit without neutral reference). This is a
> differential current discrepancy on the primary side. If you have an RCD
> (which you should), then it can or will trip due to the current imbalance.

RCD's are extremely uncommon in the USA for industrial stuff.  In fact
the term RCD itself is virtually unknown.  "Ground fault" is the term used
here.

There are two kinds of ground fault protection.  In residences, ground 
fault protected receptacles are required when near water (kitchen and
bathroom sinks, outdoor receptacles, basements, and several other
places).  These GFCI's  (Ground Fault Circuit Interrupter) are intended
to protect people from shock, and have trip points around 6mA IIRC.

In industry, ground fault relays are typically applied at the transformer,
where the neutral is grounded.  They are intended to protect against 
ground faults where the impedance might be high enough (and the 
fault current low enough) that normal overcurrent protection doesn't
trip.  But they don't protect against shock; the trip levels range from
a few amps to a few tens of amps.  They pretty much shrug off stray
capacitive leakage.

> > There are a lot of good reasons to tie one leg the transformer to ground 
> > besides to establish the safety ground and neutral as is common on the US.
> > Intermittent faults to ground, with an ungrounded system, can cause the 
> > secondary of the transformer to fly way above absolute ground causing 
> > connected devices, or the transformer to suffer from insulation 
> > breakdowns.   That's the extreme, but it can happen.
> 
> Actually, the secondary should normally be floating. Most transformer
> setups are to ensure galvanic separation and that means you may never
> connect neutral to the secondary side.

I don't think anyone is saying you would 

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 01/01/2016 07:25 PM, Kirk Wallace wrote:
>> Machine wiring is different in that you can have scenarios where
>> references are moved, especially in a 2-phase system where you are not
>> using the neutral, which is the scenario we have here.
> My understanding is, and I could be wrong, that "two-phase" in reference 
> to modern mains circuits does not exist. Circuits with two hot legs, L1 
> and L2, are single phase and referenced to each other. Two phase used to 
> be two legs that were 90 degrees apart, but is long gone.

That was (almost) my faulty thought too at first, but it turns out that
the 2-phase system referred to comes from a single transformer with two
secondary windings. This gives you two 120V lines wrt. neutral (L1 and
L2) which are 180 degrees shifted. Therefore, the difference between L1
and L2 is 240V.


-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Dammeyer]

Isn't it commonly called Split Phase in North America?

Draw 15A on each side of the 120-0-120 VAC circuit and measure that with a
clamp on ammeter and you get 15A on each leg.  Put the clamp on meter on the
white wire (the neutral return)  and you get 0A. In effect the two phases
are 180 degrees out of phase.  If it weren't so you'd have to make the white
neutral wire handle twice the current of the black (and/or  red) hot wires.

John Dammeyer


> In the USA, Kirk is 100% correct.  Two phase means 90 degree phase
> shift, and is pretty much non-existent.  120V-0V-120V with 240V from
> end to end is "single phase".  Call it two-phase and people in the States
> will look at you funny.
> 
> John Kasunich
> 
> 
> 
>

--
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Dammeyer]

Thank you.
Well said.
John Dammeyer


> -Original Message-
> From: John Kasunich [mailto:jmkasun...@fastmail.fm]
> Sent: January-01-16 4:41 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Rewiring the BP
...
> 
> Three phase or single phase doesn't matter.  When a transformer delivers
> power at 120VAC one side is grounded.  There are a few very limited
> exceptions in the code, such as:
> 
>  A control circuit derived from a transformer with a primary not
>  over 1000 volts need not be grounded if:
>  (1) only qualified persons will service the installation,
>  (2) continuity of control power is required, and
>  (3) ground detectors are installed on the control circuit. [250-21]
> 
> Some more detail at:
> http://www.ecmag.com/section/codes-standards/motor-control-circuits-
> ground-or-not-ground
> 
> 
> --
>   John Kasunich
>   jmkasun...@fastmail.fm


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Kasunich]

On Fri, Jan 1, 2016, at 08:18 PM, Bertho Stultiens wrote:
> On 01/02/2016 01:41 AM, John Kasunich wrote:
> > This is one of those cases where electrical practices on opposite
> > sides of oceans differ significantly.
> 
> Yes, there are some significant differences. That has become obvious.
> 
> 
> [snip]
> > Three phase or single phase doesn't matter.  When a transformer delivers
> > power at 120VAC one side is grounded.  There are a few very limited 
> > exceptions in the code, such as:
> [snip]
> > Some more detail at:
> > http://www.ecmag.com/section/codes-standards/motor-control-circuits-ground-or-not-ground
> 
> That is a nice link because the first paragraph apparently gives the
> answer afaics:
>   If a motor control circuit is tapped from the motor circuit and
>   does not leave the controller enclosure (the push buttons are
>   in the cover), then it need not be grounded. [90-7 ¶ 2,
>   300-1(b), 450-1 Exc.No.2]
> 
> The control circuit is inside and the PC with all other control logic
> and electronics too. Nothing ever leaves the enclosure. So, that would
> mean that my argument still holds. Or am I reading this completely wrong?
> 

"Tapped from" means directly, without a transformer.

So if you have a three-phase 480V motor, and a contactor with a 480V coil,
you could tap 480V directly from L1 and L2 to run the contactor coil, if the
control circuit doesn't leave the enclosure.  (Likewise with a 240V motor and
a 240V contactor coil).

Most of the National Electrical Code was written back when "control"
meant "motor starter", and that consisted of a contactor with start
and stop buttons.  The exception that you cited allowed for cheap
(because no transformer) motor starters, if you could live with the
buttons being on the cover of the box.

If the buttons were external, the normal arrangement for many years
was a small 480 (or whatever) to 120V control transformer, one side
grounded, start and stop buttons in the ungrounded side so an
accidental short to ground would blow a fuse instead of starting 
the motor.  Contactor coil was 120V.

We have only recently started following the rest of the world in using
24V for the buttons and coils.  Much safer, and the NEC doesn't have
nearly as much to say about how you ground (or don't ground) a 24V
circult.  Except that you still need to make sure a transformer failure
doesn't put primary voltage on the low voltage wiring.  Grounding one
side is probably the easiest way to do that.
 
John Kasunich

-- 
  John Kasunich
  jmkasun...@fastmail.fm

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 01/02/2016 01:41 AM, John Kasunich wrote:
> This is one of those cases where electrical practices on opposite
> sides of oceans differ significantly.

Yes, there are some significant differences. That has become obvious.


[snip]
> Three phase or single phase doesn't matter.  When a transformer delivers
> power at 120VAC one side is grounded.  There are a few very limited 
> exceptions in the code, such as:
[snip]
> Some more detail at:
> http://www.ecmag.com/section/codes-standards/motor-control-circuits-ground-or-not-ground

That is a nice link because the first paragraph apparently gives the
answer afaics:
If a motor control circuit is tapped from the motor circuit and
does not leave the controller enclosure (the push buttons are
in the cover), then it need not be grounded. [90-7 ¶ 2,
300-1(b), 450-1 Exc.No.2]

The control circuit is inside and the PC with all other control logic
and electronics too. Nothing ever leaves the enclosure. So, that would
mean that my argument still holds. Or am I reading this completely wrong?


-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP - where to connect ground

[Bertho Stultiens]

On 01/01/2016 10:28 PM, Bertho Stultiens wrote:
> Short explanation:
> You must ensure that a grounding connection does not carry current and
> is located at such a point where a symmetric coupling can be achieved.
> 
> A bit longer explanation:
[snip]

Just one comment on the explanation...
It is still quite a simplification of the actual electrical AC analysis
of the circuit as a whole. However, such analysis would be far beyond
the scope of this mailing list IMO. The intricacies can be subtle and
complex and sometimes slightly counter-intuitive.

Not to cut of any detailed discussion, but to prevent to go completely
off topic. Otherwise we should start a new thread for that purpose.

-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Gene Heskett]

On Friday 01 January 2016 12:03:23 John Thornton wrote:

> I just looked at the control transformer and L1 and L2 (240v side are
> fused with type CC fuses and X1 only on the 120v side is fused with a
> slo-blow fuse. So I assume they intended X2 to be the "neutral".
>
> JT
>
An excellent assumption, John. Do carry on. :)

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP - where to connect ground

[Gene Heskett]

On Friday 01 January 2016 18:04:34 Ben Potter wrote:

> > From: Bertho Stultiens [mailto:ber...@vagrearg.org]
> > A bit longer explanation:
> > See attached image. Outputs of the step-down transformer A and B are
>
> capacitively coupled to L1 and L2 through four parasitic capacitors.
>
> > Connecting A to ground when C1A not equal C2A or connecting B to
> > ground
>
> when C1B not equal C2B will create a current in the ground connection.
> 
>
> Thank you for this image - I think I've finally got my head around the
> utter basics of the American electricity supply system. Some of that
> may have been is it single/two phase?
> Having 3 phases and a neutral coming into your premises (aka UK
> 3-phase supply) somehow seems less... subject to complexity
>
> Going really OT here (and I should probably start a new thread for
> this) - what beyond a 1:1 ratio makes a transformer an 'isolation'
> transformer.
>
No ohmic connection between primary and secondary.  If there is, and its 
not just a carbon track from a lightning strike, its an autoformer, and 
potentially a killer because it doesn't isolate.  Two pieces of wire are 
exactly equal to a 1/1 autoformer IOW..

> I have used the below transformer or similar as the primary power
> transformer for machines (in the case of the 2kva one, a ram edm). And
> have considered it to provide sufficient isolation
> http://www.jmsonline.co.uk/product_info.php?cPath=22_id=54
>
> If I'm wrong, please let me know (and ideally how to fix it)
>
> Thanks
> Ben
>
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[andy pugh]

On 27 December 2015 at 00:32, John Kasunich  wrote:
> Each house has a ground rod.  The neutral from the transformer, the
> house ground rod, a connection from the house cold water plumbing (if
> copper), the neutrals from all the receptacles, and the ground wires from
> all the receptacles are all tied together at a large bus bar in the main 
> panel.


Something of a digression, but this document describes the earthing
systems legal for use in the UK
http://electrical.theiet.org/wiring-matters/16/earthing-questions.cfm

None of those seem to have an earthing spike _and_ a neutral to GND link.

-- 
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[richshoop]

Excellent references on what actually works, and stays shipped is available 
from any of the cnc machine tool manufacturers maintenance manuals. My 
reference that I used to solve my 8 year long search for intermittent noise 
problem is from Morbidelli, their U-15 machine (A woodworking oriented panel 
processor). The Italian and Spanish manufacturers are a great source since all 
of their machines have to be designed to work with electrical systems all over 
the world. 

- Original Message -

From: emc-users-requ...@lists.sourceforge.net 
To: emc-users@lists.sourceforge.net 
Sent: Friday, January 1, 2016 11:14:43 AM 
Subject: Emc-users Digest, Vol 117, Issue 7 

Send Emc-users mailing list submissions to 
emc-users@lists.sourceforge.net 

To subscribe or unsubscribe via the World Wide Web, visit 
https://lists.sourceforge.net/lists/listinfo/emc-users 
or, via email, send a message with subject or body 'help' to 
emc-users-requ...@lists.sourceforge.net 

You can reach the person managing the list at 
emc-users-ow...@lists.sourceforge.net 

When replying, please edit your Subject line so it is more specific 
than "Re: Contents of Emc-users digest..." 


Today's Topics: 

1. Re: Smart-Serial cabling (Peter C. Wallace) 
2. Re: Rewiring the BP (Bertho Stultiens) 
3. Re: Rewiring the BP (Jon Elson) 
4. Re: Rewiring the BP (andy pugh) 
5. Re: Rewiring the BP (Kirk Wallace) 
6. Re: Rewiring the BP (John Dammeyer) 
7. Re: Rewiring the BP (John Dammeyer) 


-- 

Message: 1 
Date: Fri, 1 Jan 2016 09:24:26 -0800 (PST) 
From: "Peter C. Wallace" <p...@mesanet.com> 
Subject: Re: [Emc-users] Smart-Serial cabling 
To: "Enhanced Machine Controller (EMC)" 
<emc-users@lists.sourceforge.net> 
Message-ID: <pine.neb.4.64.1601010903100.7...@freeby.mesanet.com> 
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed 

On Fri, 1 Jan 2016, andy pugh wrote: 

> Date: Fri, 1 Jan 2016 16:59:12 + 
> From: andy pugh <bodge...@gmail.com> 
> Reply-To: "Enhanced Machine Controller (EMC)" 
> <emc-users@lists.sourceforge.net> 
> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> 
> Subject: Re: [Emc-users] Smart-Serial cabling 
> 
> On 1 January 2016 at 16:16, Peter C. Wallace <p...@mesanet.com> wrote: 
>> SSerial is differential RS-422 at 2.5 MBits/sec and requires ~100 Ohm 
>> differential cable cable impedance. This usually means twisted pairs 
>> are required for TX and RX (the 5V/GND power connections are not critical) 
> 
> The pairs are twisted inside the individual foil screen with drain 
> wire then there are 4 other small (0.14mm2) wires and two bigger 
> (0.5mm2) wires all inside an overall braided screen. 
> 
> I suppose the thing to do is to try it and see. I have determined that 
> the pairs fit nicely in an RJ45 connector, but I can't decide what to 
> do about the 2x 5V and 2x 0V positions in the connector. Are the 0V 
> and 5V contacts commoned at the PCB ends, such that leaving two 
> positions unpopulated in the RJ45 is OK? I only need enough 5V power 
> to run the 7i73 logic. 

Yes, they are commoned at the sserial remote and FPGA side RS-422 interface 



> 
> -- 
> atp 
> If you can't fix it, you don't own it. 
> http://www.ifixit.com/Manifesto 
> 
> --
>  
> ___ 
> Emc-users mailing list 
> Emc-users@lists.sourceforge.net 
> https://lists.sourceforge.net/lists/listinfo/emc-users 
> 

Peter Wallace 
Mesa Electronics 

(\__/) 
(='.'=) This is Bunny. Copy and paste bunny into your 
(")_(") signature to help him gain world domination. 




-- 

Message: 2 
Date: Fri, 1 Jan 2016 18:29:16 +0100 
From: Bertho Stultiens <ber...@vagrearg.org> 
Subject: Re: [Emc-users] Rewiring the BP 
To: "Enhanced Machine Controller (EMC)" 
<emc-users@lists.sourceforge.net> 
Message-ID: <5686b76c.4030...@vagrearg.org> 
Content-Type: text/plain; charset=windows-1252 

On 01/01/2016 05:47 PM, Dave Cole wrote: 
> That's done all of the time. In fact it is part of the NEC (National 
> Electric Code) that is followed (for the most part) in the US. 
> Pretty much every house in the US is wired like that. (I'm not making 
> this stuff up. :-) ) 

I agree with the connection at power entry in the house. That is quite a 
different story. That is actually the same here in EU (most countries). 

I think that we should separate two things: 
- house installation 
- machine wiring 

House installation is pretty much standardized with a lot of rules and 
reasons. Specifically to ensure referencing and protection. 

Machine wiring is different in that yo

Re: [Emc-users] Rewiring the BP - where to connect ground

[Bertho Stultiens]

On 01/01/2016 08:24 PM, Rafael wrote:
>> There are a lot of good reasons to tie one leg the transformer to ground
>> besides to establish the safety ground and neutral as is common on the US.
>> Intermittent faults to ground, with an ungrounded system, can cause the
>> secondary of the transformer to fly way above absolute ground causing
>> connected devices, or the transformer to suffer from insulation
>> breakdowns.   That's the extreme, but it can happen.
> 
> Strongly agree! Do not float transformer secondary and have a PC 
> connected to it! This is not about an isolation transformer, it's about 
> stepdown transformer which is way different. Primary side of this step 
> down transformer needs to float in this case. In ideal situation, CT on 
> the primary side would be neutral and connected to local ground but it 
> is better to not use it; transformer is not ideal.

For good measure; I did not say that you should not ground the PC.
Actually, I noted that it already is, but it is grounded at a
_different_ point in the chain of connections.

There is a reason why the PC /should/ be grounded and that has been
underlined in the replies here. The question that seems to be popping up
is _where_ to have the ground connected.

Short explanation:
You must ensure that a grounding connection does not carry current and
is located at such a point where a symmetric coupling can be achieved.


A bit longer explanation:
See attached image. Outputs of the step-down transformer A and B are
capacitively coupled to L1 and L2 through four parasitic capacitors.
Connecting A to ground when C1A not equal C2A or connecting B to ground
when C1B not equal C2B will create a current in the ground connection.

CxA and CxB form capacitive voltage dividers, which will create a
virtual zero point equal to neutral only if both capacitors are equal.
Otherwise, you will have a potential differential and therefore a
current through the ground connection from the secondary(*).

An RCD measures the currents IL1 and IL2 where it must be ensured that
IL1 + IL2 < threshold, where threshold depends on the particular RCD.
When you cannot guarantee that the ground-current is zero, because the
capacitive couplings are not equal, then you risk tripping the RCD. If
you have no RCD, then you are creating an unbalanced circuit that will
come to haunt you at another time (any imbalance in L1 and L2 will
propagate through the system wreaking havoc).

If you look at the DC side of the system, then you have a symmetric
coupling from 0V (DC) to both A and B through Cf. The coupling stems
from the rectifier system, which couples both A and B through the same
circuit (which is why Cf is drawn twice).

Therefore, connecting the output of the PSU's 0V (DC) line to ground
will carry nearly(**) no current. This will protect the whole circuit
from inadvertent potentials and calm the noise in the system.


The /problem/ with having 0V (DC) at ground are again the rise of the
dreaded ground-loops. If you have multiple PSUs all connected to ground
and connecting the 0V (DC) lines through the signal return connections,
then you have two distinct paths (a loop). That is where you need the
galvanic isolator(s) to break the ground-loop.


(*) JT has done a measurement that show a different voltage from
A-to-ground and B-to-ground. Thereby establishing that the parasitic
capacitances are not equal.

(**) the parasitic capacitances are in series and the differentials are
guaranteed less than 90 degrees shifted. The effective leakage is
normally in the order of micro-amps and a few orders of magnitude away
from tripping an RCD.


>> One of way too many references on the web.
>> http://ecmweb.com/bonding-amp-grounding/basics-bonding-and-grounding-transformers
> I hope that nobody gets zapped before this highly charged and perhaps 
> the long(est) thread is over.

Always have a bleeder resistor over your caps. Running a bleeder
resistor over an email-thread helps too ;-)

And then, coffee will help too.

-- 
Greetings Bertho

(disclaimers are disclaimed)
--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 01/02/2016 12:24 AM, Gene Heskett wrote:
> this is a single phase system delivering 240+ volts AC 
> to the two ends of a single core transformers primary winding.

Well, yes and no. It depends on what you are looking at.

The point in normal AC systems is that your ground potential is at or
near neutral potential. In the system we have here, we have no neutral
and ground is at half the potential of the input.


> While I personally am not 100% happy with a no neutral hook up, it is 
> legal as long as it never leaves the confines of the load machine.  The 
> machine itself is grounded well.  The fact that the core/frame of the 
> control transformer isn't grounded probably enhances the capacitative 
> coupling, which might amount to something in the 100 pF neighborhood.  
> If the frame/core were also grounded, I would expect some of that 
> un-balance to go away and the total, added up, would be less than the 
> delivered voltage primarily because the measureing meter is going to 
> absorb some of it when hooked up to measure it, causing its own 
> imbalance.

Some points here; I agree with the no-neutral is a problem assessment.
However, that is something we have to live with.

Capacitive coupling does not depend on being grounded or not. It is an
inherent property of wires running close to each other, such as in a
transformer.

The capacitance is often a bit higher, but that does not matter too much
for the argument. The unbalance as JT showed is measuring with the same
multimeter at two points. The fact that two different values com out of
that is enough to conclude that the imbalance is in the
system-under-measurement and not caused by the multimeter. Otherwise you
would see the same discrepancy for both measurements. I have not seen a
multimeter that is so bad that it will throw a measurement off more that
few percent.


[snip]
> The reason I wrote 240+ is that 127+127=254, which if Johns meter is a 
> decent one, he should be reading within say 2 volts of that from L1 to 
> L2.  With no neutral, only the secondary of that control transformer is 
> to be considered the src of a 127 volt AC feed, and either end of it can 
> and should be tied to the well grounded machine frame, but not both of 
> course.  Having it grounded gives a direct path to ground for the noises 
> the VFD might induce from close proximity.

This is where we disagree. Whether it is 2x120V=240V or 2x127V=254V does
not matter. The principle of re-referencing an un-referenced system in
the way you suggest is wrong for the purpose because the installation
does not leave the machine. If this was part of a house-installation,
then I'd agree to re-referencing, but it is not.

Also, the VFD's path to ground is quite a different one from the one
after the transformer.

A good grounding plan for the entire machine and a careful plan of /all/
other wiring is how you reduce the noise. There are many more gotchas
than just one ground connection or a VFD. It is the connection plan as a
whole that defines immunity and stability.

-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP - where to connect ground

[Ben Potter]

> From: Bertho Stultiens [mailto:ber...@vagrearg.org] 
> A bit longer explanation:
> See attached image. Outputs of the step-down transformer A and B are
capacitively coupled to L1 and L2 through four parasitic capacitors.
> Connecting A to ground when C1A not equal C2A or connecting B to ground
when C1B not equal C2B will create a current in the ground connection.


Thank you for this image - I think I've finally got my head around the utter
basics of the American electricity supply system. Some of that may have been
is it single/two phase?
Having 3 phases and a neutral coming into your premises (aka UK 3-phase
supply) somehow seems less... subject to complexity

Going really OT here (and I should probably start a new thread for this) -
what beyond a 1:1 ratio makes a transformer an 'isolation' transformer.

I have used the below transformer or similar as the primary power
transformer for machines (in the case of the 2kva one, a ram edm). And have
considered it to provide sufficient isolation
http://www.jmsonline.co.uk/product_info.php?cPath=22_id=54

If I'm wrong, please let me know (and ideally how to fix it)

Thanks
Ben


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 01/02/2016 01:47 AM, John Kasunich wrote:
> This is ENTIRELY a function of where you are and what language you 
> speak.  (English and American are not the same language :-)  

Yes, and neither is my native language... I'm trying, so confusion is
probably pre-programmed for some "features" and hope I can be forgiven ;-)


-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Gene Heskett]

On Friday 01 January 2016 12:29:16 Bertho Stultiens wrote:

> On 01/01/2016 05:47 PM, Dave Cole wrote:
> > That's done all of the time.   In fact it is part of the NEC
> > (National Electric Code) that is followed (for the most part) in the
> > US. Pretty much every house in the US is wired like that.  (I'm not
> > making this stuff up.  :-) )
>
> I agree with the connection at power entry in the house. That is quite
> a different story. That is actually the same here in EU (most
> countries).
>
> I think that we should separate two things:
> - house installation
> - machine wiring
>
> House installation is pretty much standardized with a lot of rules and
> reasons. Specifically to ensure referencing and protection.
>
> Machine wiring is different in that you can have scenarios where
> references are moved, especially in a 2-phase system where you are not
> using the neutral, which is the scenario we have here.
>
> > Now, if you don't want to do that inside the panel for some reason
> > (which I might have missed), that may be a different story.
> > I'm just saying that is standard practice in the US and on the
> > European machines I have worked on as well.
>
> The reason for /not/ connecting the ground on a secondary winding is
> to prevent a capacitively coupled ground path. Especially if you
> cannot guarantee a 100% balanced primary-to-secondary side wrt. ground
> (*).
>
> What happens is that there will be a current in the ground connection
> which causes an imbalanced current on the primary side (remember:
> primary is 2-phase circuit without neutral reference). This is a
> differential current discrepancy on the primary side. If you have an
> RCD (which you should), then it can or will trip due to the current
> imbalance.
>
>
> (*) and from the example measurements presented by JT, we can be
> assured that there is an imbalance, as seen from the phase shift
> causing a difference in voltage measured wrt. ground on the secondary.
>
> > There are a lot of good reasons to tie one leg the transformer to
> > ground besides to establish the safety ground and neutral as is
> > common on the US. Intermittent faults to ground, with an ungrounded
> > system, can cause the secondary of the transformer to fly way above
> > absolute ground causing connected devices, or the transformer to
> > suffer from insulation breakdowns.   That's the extreme, but it can
> > happen.
>
> Actually, the secondary should normally be floating. Most transformer
> setups are to ensure galvanic separation and that means you may never
> connect neutral to the secondary side.
>
> Connecting ground on a secondary is a different scenario, where you
> most often see the 0V (DC) potential connected to protective ground.
> This is often done in the PC's power supply. The 0V (DC) to protective
> ground connection prevents the scenario to which you refer to.
>
> The 0V (DC) to protective ground connection is repeated in many
> devices, which have both power and signal connections. This gives rise
> to ground-loops, which are to be prevented at all times and it is the
> cause of the whole thread.
>
> > One of way too many references on the web.
> > http://ecmweb.com/bonding-amp-grounding/basics-bonding-and-grounding
> >-transformers
>
> It looks like the link is about a 3-phase system, where you would
> connect the center point in a star-configured secondary to ground.
> That is a different scenario.

So is this Bertho, this is a single phase system delivering 240+ volts AC 
to the two ends of a single core transformers primary winding.

While I personally am not 100% happy with a no neutral hook up, it is 
legal as long as it never leaves the confines of the load machine.  The 
machine itself is grounded well.  The fact that the core/frame of the 
control transformer isn't grounded probably enhances the capacitative 
coupling, which might amount to something in the 100 pF neighborhood.  
If the frame/core were also grounded, I would expect some of that 
un-balance to go away and the total, added up, would be less than the 
delivered voltage primarily because the measureing meter is going to 
absorb some of it when hooked up to measure it, causing its own 
imbalance.

In short, this is not a 2 phase system where the phase angles are +- 90 
degrees, so for practical purposes the 2 phase math is irrelevant.

The reason I wrote 240+ is that 127+127=254, which if Johns meter is a 
decent one, he should be reading within say 2 volts of that from L1 to 
L2.  With no neutral, only the secondary of that control transformer is 
to be considered the src of a 127 volt AC feed, and either end of it can 
and should be tied to the well grounded machine frame, but not both of 
course.  Having it grounded gives a direct path to ground for the noises 
the VFD might induce from close proximity.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)

Re: [Emc-users] Rewiring the BP

[Gene Heskett]

On Friday 01 January 2016 12:34:37 Jon Elson wrote:

> On 01/01/2016 06:02 AM, John Thornton wrote:
> > Hi Jon,
> >
> > So tie say the 48v side to ground to create the neutral? I
> > attached the drawing of what I have so far on the VFD side.
>
> With power off, use an Ohmmeter to verify the secondary is
> isolated from the frame.  If so, tie either end to ground.
> If NOT, then further investigation is required.
>
> > Happy New year to you and I hope you stayed dry during the
> > recent monsoon we got.
>
> It was fine here, but lots of highways closed.  My mother in
> law's house had some basement leakage.  During the strongest
> rain, we had a drip where the furnace flue goes through the
> roof.
>
> Jon
>
Good to hear Jon, thanks.

> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 01/01/2016 08:13 PM, John Dammeyer wrote:
> (Reposted with link to pdf fixed)
> Here's what I did for my SouthBend Lathe.  Not run with CNC but with my
> Electronic Lead Screw.
> http://www.autoartisans.com/Lathe/SouthBendPower.pdf

The connection from the secondary to ground (chassis) effectively kills
the common-mode filter which is located inside your computer's power
supply. You have shorted one side of the common-mode filter, rendering
it completely ineffective and injecting the computer's PSU noise into
the chassis.

See my other mail for a detailed explanation.

-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Kasunich]

On Fri, Jan 1, 2016, at 04:44 PM, Bertho Stultiens wrote:
> On 01/01/2016 07:25 PM, Kirk Wallace wrote:
> >> Machine wiring is different in that you can have scenarios where
> >> references are moved, especially in a 2-phase system where you are not
> >> using the neutral, which is the scenario we have here.
> > My understanding is, and I could be wrong, that "two-phase" in reference 
> > to modern mains circuits does not exist. Circuits with two hot legs, L1 
> > and L2, are single phase and referenced to each other. Two phase used to 
> > be two legs that were 90 degrees apart, but is long gone.
> 
> That was (almost) my faulty thought too at first, but it turns out that
> the 2-phase system referred to comes from a single transformer with two
> secondary windings. This gives you two 120V lines wrt. neutral (L1 and
> L2) which are 180 degrees shifted. Therefore, the difference between L1
> and L2 is 240V.
 
This is ENTIRELY a function of where you are and what language you 
speak.  (English and American are not the same language :-)  

In the USA, Kirk is 100% correct.  Two phase means 90 degree phase 
shift, and is pretty much non-existent.  120V-0V-120V with 240V from
end to end is "single phase".  Call it two-phase and people in the States
will look at you funny.

John Kasunich



--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

Hi Gene,

The frame is most solidly grounded. I'll do the tests in a bit. Keep in 
mind that I have a 240v to 120v step down transformer to supply the 120v 
not a normal house circuit. Again an effort to kill the noise. Which by 
the way I'm running 2.7 now after changing the wires on the limit/home 
switches to twisted pair shielded wire. I've attached the VFD side 
wiring diagram. I assume the connection is through the neutral bonding 
screw at the panel because the step down transformer is isolated from 
ground.


Happy New Year to you too.

JT

On 12/31/2015 5:50 PM, Gene Heskett wrote:

On Thursday 31 December 2015 16:20:40 John Thornton wrote:


On the 120v side if I measure from the hot to the ground I get 79
volts, if I measure from hot to neutral I get the expected 128v...
what is that telling me?

JT

My first guess is that the Bridgeport itself, is not grounded.  It really
should be, just to keep it from becoming lethally hot when somethings
insulation fails.  Generally speaking, if I can measure more than a volt
between neutral and the static ground, it concerns me UNLESS its a wild
phase , which I don't believe you have since its not a 3 phase circuit.

TBE if something is running that uses that neutral you might see more
volts, but I'd re-measure after turning whatever it was off.

As to the 79 volts, I would put a small light bulb (7.5 watt night lite)
from the Bp frame to neutral to see if there is any real current, or its
just capacitative coupling. If capacitative coupling, a 7.5 watt night
light bulb will remain dark, and that voltage should drop to less than 1
or 2 volts. If it lights up at all, and the voltage doesn't drop
drastically, there really is a fault someplace.  I'd start disconnecting
motors for starters.

Happy New Year John.

Cheers, Gene Heskett


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 12/31/2015 10:24 PM, John Thornton wrote:
> I went and checked the control transformer and one side is 48v to ground 
> and the other side is 79v to ground. I guess I was confused by that.

I did a quick calculation and if your protective ground has a voltage
with a phase shift of about 62 degrees wrt. the transformer's output and
the open voltage of the transformer is 132V, then one lead will show 48V
(RMS)(*) and the other will show 80V (RMS) with respect to ground.

>From this we can conclude that you are measuring a capacitive coupling.


Calculated from:
Ground potential : V * sin(a + p)
Transformer out A: V * sin(a)
Transformer out B: V * sin(-a)

with:   a = running angle
p = phase shift
V = Voltage

Transformer output A wrt. ground:
V * RMS(sin(a) - sin(a + p))
Transformer output B wrt. ground:
V * RMS(sin(-a) - sin(a + p))


(*) I assume that your multimeter is measuring root-mean-square (RMS)
voltage in AC mode. That should be a pretty safe assumption.

-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

Ground to chassis is 0.01 ohm.

JT

On 1/1/2016 7:42 AM, Bertho Stultiens wrote:
> There is one remaining measurement that you should do: Measure the DC 
> resistance between the chassis and the protective ground of the 
> wall-outlet. That should be close to zero. Then, assuming that the 
> wall-outlet's ground is properly connected, you have assured that you 
> actually have a protective ground connected to your equipment. 


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

Hi Jon,

So tie say the 48v side to ground to create the neutral? I attached the 
drawing of what I have so far on the VFD side.


Happy New year to you and I hope you stayed dry during the recent 
monsoon we got.


JT

On 12/31/2015 7:16 PM, Jon Elson wrote:

On 12/31/2015 03:24 PM, John Thornton wrote:

I went and checked the control transformer and one side is 48v to ground
and the other side is 79v to ground. I guess I was confused by that.


Do you have a ground connected to that winding?  If not,
then the capacitance of that winding to other windings and
the core will set what AC potential you get at each end.
I'm guessing you have a totally floating secondary, and this
adds up to 127 VAC, which sounds right for a nominal 120 V
output.  You can tie one end of the winding to frame ground,
establishing a new neutral in the cabinet for the computer,
etc. loads.

Jon

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 01/01/2016 01:02 PM, John Thornton wrote:
> So tie say the 48v side to ground to create the neutral? I attached the
> drawing of what I have so far on the VFD side.

No, then you just short a capacitive path to ground.

If you have no neutral, then you do not have it. All voltages you
measure wrt. ground are relative values and are influenced by the
induced phase angle of whatever you have on the lines wrt. ground.

The ground line will be floating due to capacitive couplings and it may
not be entirely symmetric from the phases L1 and L2. Therefore, if you
mesaure wrt. ground, you see differences in the RMS voltage. The
multimeter is no real load and will not influence the phase angle of any
capacitive coupling. However, note that such measurements do not
represent the the voltages you have at your displosal for the loads.

There are in principle only two voltages you can measure:
- input lines between L1 and L2 -> ~240V
- after the transformer at the output of the transformer -> ~120V

These are the only voltages that make sense to measure.

There is one remaining measurement that you should do: Measure the DC
resistance between the chassis and the protective ground of the
wall-outlet. That should be close to zero.
Then, assuming that the wall-outlet's ground is properly connected, you
have assured that you actually have a protective ground connected to
your equipment.

-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Dave Cole]

Yes,

Anytime you have a 120 volt source for computer, misc power etc, you 
need to declare one side of the 120 vac winding the neutral (white wire) 
and tie that terminal to the machine frame.
It similar to what is required at the service entrance of your house.  
The neutral is always tied to the ground at the entrance box.   
Oftentimes they drive  a screw through the neutral buss bar in the 
service entrance box into the box sheetmetal and then tie a green or 
bare copper ground wire to the same neutral buss bar and run that to a 
metal water pipe or ground rod.   Oftentimes they just put a green 
copper jumper wire between the "declared" neutral terminal on the 
transformer and the transformer attachment screw in the panel and they 
use the steel panel backplane for "ground". If you are using a single 
point ground just run a green ground wire from the neutral terminal on 
the transformer and the single point ground in the panel.

Dave

On 1/1/2016 7:02 AM, John Thornton wrote:
> Hi Jon,
>
> So tie say the 48v side to ground to create the neutral? I attached 
> the drawing of what I have so far on the VFD side.
>
> Happy New year to you and I hope you stayed dry during the recent 
> monsoon we got.
>
> JT
>
> On 12/31/2015 7:16 PM, Jon Elson wrote:
>> On 12/31/2015 03:24 PM, John Thornton wrote:
>>> I went and checked the control transformer and one side is 48v to 
>>> ground
>>> and the other side is 79v to ground. I guess I was confused by that.
>>>
>> Do you have a ground connected to that winding?  If not,
>> then the capacitance of that winding to other windings and
>> the core will set what AC potential you get at each end.
>> I'm guessing you have a totally floating secondary, and this
>> adds up to 127 VAC, which sounds right for a nominal 120 V
>> output.  You can tie one end of the winding to frame ground,
>> establishing a new neutral in the cabinet for the computer,
>> etc. loads.
>>
>> Jon
>>
>> --
>>  
>>
>> ___
>> Emc-users mailing list
>> Emc-users@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/emc-users
>
>
>
> --
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Dammeyer]

Here's what I did for my SouthBend Lathe.  Not run with CNC but with my
Electronic Lead Screw.

http://www.autoartisans.com/lathe/SouthBendPower.pdf
http://www.autoartisans.com/Lathe/ControlBox.jpg
http://www.autoartisans.com/Lathe/ControlBoxInside.jpg

The System Relay is wired as a latching relay that stays ON until ESTOP is
hit.  Both the coolant pump switch and Spindle Start relay must be off
before the Relay is energized.  An ESTOP disconnects power to the dangerous
voltages but leaves the ELS powered.  Since I fed this box with 220VAC there
is no neutral and I used a transformer to power a split duplex outlet.  One
side of the 120VAC is bonded to Earth.

I haven't had any electrical noise problems.  But I have also not yet wired
the RS232 port of the ELS to the VFD for speed control.

John Dammeyer



> -Original Message-
> From: Dave Cole [mailto:linuxcncro...@gmail.com]
> Sent: January-01-16 8:14 AM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Rewiring the BP
> 
> 
> Yes,
> 
> Anytime you have a 120 volt source for computer, misc power etc, you
> need to declare one side of the 120 vac winding the neutral (white wire)
> and tie that terminal to the machine frame.
> It similar to what is required at the service entrance of your house.
> The neutral is always tied to the ground at the entrance box.
> Oftentimes they drive  a screw through the neutral buss bar in the
> service entrance box into the box sheetmetal and then tie a green or
> bare copper ground wire to the same neutral buss bar and run that to a
> metal water pipe or ground rod.   Oftentimes they just put a green
> copper jumper wire between the "declared" neutral terminal on the
> transformer and the transformer attachment screw in the panel and they
> use the steel panel backplane for "ground". If you are using a single
> point ground just run a green ground wire from the neutral terminal on
> the transformer and the single point ground in the panel.
> 
> Dave
> 
> On 1/1/2016 7:02 AM, John Thornton wrote:
> > Hi Jon,
> >
> > So tie say the 48v side to ground to create the neutral? I attached
> > the drawing of what I have so far on the VFD side.
> >
> > Happy New year to you and I hope you stayed dry during the recent
> > monsoon we got.
> >
> > JT
> >
> > On 12/31/2015 7:16 PM, Jon Elson wrote:
> >> On 12/31/2015 03:24 PM, John Thornton wrote:
> >>> I went and checked the control transformer and one side is 48v to
> >>> ground
> >>> and the other side is 79v to ground. I guess I was confused by that.
> >>>
> >> Do you have a ground connected to that winding?  If not,
> >> then the capacitance of that winding to other windings and
> >> the core will set what AC potential you get at each end.
> >> I'm guessing you have a totally floating secondary, and this
> >> adds up to 127 VAC, which sounds right for a nominal 120 V
> >> output.  You can tie one end of the winding to frame ground,
> >> establishing a new neutral in the cabinet for the computer,
> >> etc. loads.
> >>
> >> Jon
> >>
> >>

--
> >>
> >> ___
> >> Emc-users mailing list
> >> Emc-users@lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/emc-users
> >
> >
> >
> >

--
> >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>

--
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Dammeyer]

(Reposted with link to pdf fixed)

Here's what I did for my SouthBend Lathe.  Not run with CNC but with my
Electronic Lead Screw.

http://www.autoartisans.com/Lathe/SouthBendPower.pdf
http://www.autoartisans.com/Lathe/ControlBox.jpg
http://www.autoartisans.com/Lathe/ControlBoxInside.jpg

The System Relay is wired as a latching relay that stays ON until ESTOP is
hit.  Both the coolant pump switch and Spindle Start relay must be off
before the Relay is energized.  An ESTOP disconnects power to the dangerous
voltages but leaves the ELS powered.  Since I fed this box with 220VAC there
is no neutral and I used a transformer to power a split duplex outlet.  One
side of the 120VAC is bonded to Earth.

I haven't had any electrical noise problems.  But I have also not yet wired
the RS232 port of the ELS to the VFD for speed control.

John Dammeyer



> -Original Message-
> From: Dave Cole [mailto:linuxcncro...@gmail.com]
> Sent: January-01-16 8:14 AM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Rewiring the BP
> 
> 
> Yes,
> 
> Anytime you have a 120 volt source for computer, misc power etc, you
> need to declare one side of the 120 vac winding the neutral (white wire)
> and tie that terminal to the machine frame.
> It similar to what is required at the service entrance of your house.
> The neutral is always tied to the ground at the entrance box.
> Oftentimes they drive  a screw through the neutral buss bar in the
> service entrance box into the box sheetmetal and then tie a green or
> bare copper ground wire to the same neutral buss bar and run that to a
> metal water pipe or ground rod.   Oftentimes they just put a green
> copper jumper wire between the "declared" neutral terminal on the
> transformer and the transformer attachment screw in the panel and they
> use the steel panel backplane for "ground". If you are using a single
> point ground just run a green ground wire from the neutral terminal on
> the transformer and the single point ground in the panel.
> 
> Dave
> 
> On 1/1/2016 7:02 AM, John Thornton wrote:
> > Hi Jon,
> >
> > So tie say the 48v side to ground to create the neutral? I attached
> > the drawing of what I have so far on the VFD side.
> >
> > Happy New year to you and I hope you stayed dry during the recent
> > monsoon we got.
> >
> > JT
> >
> > On 12/31/2015 7:16 PM, Jon Elson wrote:
> >> On 12/31/2015 03:24 PM, John Thornton wrote:
> >>> I went and checked the control transformer and one side is 48v to
> >>> ground
> >>> and the other side is 79v to ground. I guess I was confused by that.
> >>>
> >> Do you have a ground connected to that winding?  If not,
> >> then the capacitance of that winding to other windings and
> >> the core will set what AC potential you get at each end.
> >> I'm guessing you have a totally floating secondary, and this
> >> adds up to 127 VAC, which sounds right for a nominal 120 V
> >> output.  You can tie one end of the winding to frame ground,
> >> establishing a new neutral in the cabinet for the computer,
> >> etc. loads.
> >>
> >> Jon
> >>
> >>

--
> >>
> >> ___
> >> Emc-users mailing list
> >> Emc-users@lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/emc-users
> >
> >
> >
> >

--
> >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>

--
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users



--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Jon Elson]

On 01/01/2016 11:37 AM, andy pugh wrote:
> On 1 January 2016 at 17:29, Bertho Stultiens  wrote:
>> The reason for /not/ connecting the ground on a secondary winding is to
>> prevent a capacitively coupled ground path.
> Another reason is that if you connect either secondary winding end  to
> ground using body parts then nothing bad happens. This is the point of
> an isolation transformer.
> If there is an isolation transformer fitted in the machine then
> grounding one of its terminals makes it pointless.
>
Well, it still isolates the 120 V circuit from disturbances 
on the 240 V input.  So, if your building ground to neutral 
has a bunch of noise or offsets between them, the internal 
120 V circuit will be "clean" with respect to the frame ground.

The problem with a totally floating 120 V circuit is that 
various devices plugged in to that system may have somewhat 
large capacitors between hot or neutral and safety ground.  
Very typical in switching power supplies.  Depending on the 
configuration of all the devices on that supply, it could 
cause the neutral to be higher than the hot (with respect to 
ground).  This could cause some equipment to malfunction, if 
they assume the neutral will stay near ground potential.  
Also, a fault in one of the units could persist for some 
time until somebody touches something, and gets a nasty shock.

Open safety grounds are a common problem in the US.  I've 
gotten zapped quite good a few times when touching two 
pieces of equipment at the same time.  Leaving the secondary 
totally floating is kind of the same thing.  In the UK, they 
ground the center tap of those job site transformers for 
exactly this reason.

Now, when testing inside power equipment using an isolation 
transformer so you can use a scope on a switching power 
supply, for instance, then you DO want the transformer 
secondary floating.

Jon

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Rafael]

On 01/01/2016 08:47 AM, Dave Cole wrote:
> On 1/1/2016 11:26 AM, Bertho Stultiens wrote:
>> On 01/01/2016 05:13 PM, Dave Cole wrote:
>>> Anytime you have a 120 volt source for computer, misc power etc, you
>>> need to declare one side of the 120 vac winding the neutral (white wire)
>>> and tie that terminal to the machine frame.
>>> It similar to what is required at the service entrance of your house.
>>> The neutral is always tied to the ground at the entrance box.
>>> Oftentimes they drive  a screw through the neutral buss bar in the
>>> service entrance box into the box sheetmetal and then tie a green or
>>> bare copper ground wire to the same neutral buss bar and run that to a
>>> metal water pipe or ground rod.
>> You should never tie a secondary winding of a transformer to ground. The
>> transformer makes the secondary float wrt. the primary and that is just
>> fine.
>>
>> In this scenario, you would create a (capacitive) feed-through from the
>> transformer to ground because the primary is not referenced at ground.
>> The primary has two phases attached, which creates a virtual circuit at
>> the primary side.
>>
>> The difficulty here is that you must take account for the floating
>> references, which make most of the things you measure local phenomena.
>> Once you go through the transformer, your reference to the primary line
>> input is lost and you must not try to reestablish it. It would only make
>> things bad and worse.
>>
> Hi Bertho,
>
> That's done all of the time.   In fact it is part of the NEC (National
> Electric Code) that is followed (for the most part) in the US.

(for the most part) unfortunately. Books on this subject matter say the 
same thing. When cities have their own codes I wonder about it 
sometimes. It's about physics, not about politically correct or union 
prescribed codes that matters. I've seen silly codes in EU as well as in 
the US. Code is not going to kill, but large amount of moving electrons 
will.

> Pretty much every house in the US is wired like that.  (I'm not making
> this stuff up.  :-) )
>
> Now, if you don't want to do that inside the panel for some reason
> (which I might have missed), that may be a different story.
> I'm just saying that is standard practice in the US and on the European
> machines I have worked on as well.
>
> There are a lot of good reasons to tie one leg the transformer to ground
> besides to establish the safety ground and neutral as is common on the US.
> Intermittent faults to ground, with an ungrounded system, can cause the
> secondary of the transformer to fly way above absolute ground causing
> connected devices, or the transformer to suffer from insulation
> breakdowns.   That's the extreme, but it can happen.

Strongly agree! Do not float transformer secondary and have a PC 
connected to it! This is not about an isolation transformer, it's about 
stepdown transformer which is way different. Primary side of this step 
down transformer needs to float in this case. In ideal situation, CT on 
the primary side would be neutral and connected to local ground but it 
is better to not use it; transformer is not ideal.

A PC or anything else for that matter, that is not grounded is against 
all safety rules based on physics, never mind the code. You don't want 
your mouse or the monitor electrically float in relation to the metal 
machine!

For comparison, I used _isolation_ transformer (that is 1:1) to repair 
switching power supplies in early 90's when it was still profitable. 
Oscilloscope ground was connected to a point on the "primary side" of 
switching power supply and 1MOhm probe was good for hundreds of volts. 
Of course, I was well isolated from the "house ground" and made sure I 
didn't touch grounds on scope or outlet ground to be safe. Touching 
outlet and scope ground could of course be fatal!

One of magazines [1] in the 70's suggested to use a neutral wire if you 
don't have an antenna for the radio. Experiment for my first AM and SW 
radio detector worked fine until one day I accidentally reversed the 
plug, yes you can do that in one of STUPID EU power outlet designs, DIN 
code in my case I believe. I mention this to support my thesis that 
"electric codes" don't necessarily cover all aspects of safety.

Based on that experience I lost my interest in electricity and 
experiments for a week which surprised my mom knowing that building a 
radio detector with 3 or 5 transistors, handmade coils, all on PCB with 
traces cut with a knife was fun.

Since then I always used only one hand to work on live mainframe power 
supplies and such. That experience also confirmed my interests in "low 
voltage" side of electric phenomena: radios, TV, computers ;-)  There 
were exceptions to my work, like TVs and radios with vacuum tubes ...

[1] I don't think they write such articles anymore. I hope not.

> One of way too many references on the web.
> http://ecmweb.com/bonding-amp-grounding/basics-bonding-and-grounding-transformers
>
> 

Re: [Emc-users] Rewiring the BP

[Dave Cole]

On 1/1/2016 11:26 AM, Bertho Stultiens wrote:
> On 01/01/2016 05:13 PM, Dave Cole wrote:
>> Anytime you have a 120 volt source for computer, misc power etc, you
>> need to declare one side of the 120 vac winding the neutral (white wire)
>> and tie that terminal to the machine frame.
>> It similar to what is required at the service entrance of your house.
>> The neutral is always tied to the ground at the entrance box.
>> Oftentimes they drive  a screw through the neutral buss bar in the
>> service entrance box into the box sheetmetal and then tie a green or
>> bare copper ground wire to the same neutral buss bar and run that to a
>> metal water pipe or ground rod.
> You should never tie a secondary winding of a transformer to ground. The
> transformer makes the secondary float wrt. the primary and that is just
> fine.
>
> In this scenario, you would create a (capacitive) feed-through from the
> transformer to ground because the primary is not referenced at ground.
> The primary has two phases attached, which creates a virtual circuit at
> the primary side.
>
> The difficulty here is that you must take account for the floating
> references, which make most of the things you measure local phenomena.
> Once you go through the transformer, your reference to the primary line
> input is lost and you must not try to reestablish it. It would only make
> things bad and worse.
>
Hi Bertho,

That's done all of the time.   In fact it is part of the NEC (National 
Electric Code) that is followed (for the most part) in the US.
Pretty much every house in the US is wired like that.  (I'm not making 
this stuff up.  :-) )

Now, if you don't want to do that inside the panel for some reason 
(which I might have missed), that may be a different story.
I'm just saying that is standard practice in the US and on the European 
machines I have worked on as well.

There are a lot of good reasons to tie one leg the transformer to ground 
besides to establish the safety ground and neutral as is common on the US.
Intermittent faults to ground, with an ungrounded system, can cause the 
secondary of the transformer to fly way above absolute ground causing 
connected devices, or the transformer to suffer from insulation 
breakdowns.   That's the extreme, but it can happen.

One of way too many references on the web.
http://ecmweb.com/bonding-amp-grounding/basics-bonding-and-grounding-transformers

Dave

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

I just looked at the control transformer and L1 and L2 (240v side are 
fused with type CC fuses and X1 only on the 120v side is fused with a 
slo-blow fuse. So I assume they intended X2 to be the "neutral".

JT

On 1/1/2016 10:15 AM, Gene Heskett wrote:
> On Friday 01 January 2016 07:00:31 John Thornton wrote:
>
>> Hi Gene,
>>
>> The frame is most solidly grounded. I'll do the tests in a bit. Keep
>> in mind that I have a 240v to 120v step down transformer to supply the
>> 120v not a normal house circuit. Again an effort to kill the noise.
>> Which by the way I'm running 2.7 now after changing the wires on the
>> limit/home switches to twisted pair shielded wire. I've attached the
>> VFD side wiring diagram. I assume the connection is through the
>> neutral bonding screw at the panel because the step down transformer
>> is isolated from ground.
>>
>> Happy New Year to you too.
>>
>> JT
> So this then was my 2nd guess, is the capacitative interwinding coupling
> in that transformer capable of supplying a very few microamps of actual
> current, probably less than 1 or 2. With no loads plugged in, you could
> connect either of the output phases of that transformer to machine
> frame "ground" without any fireworks which would bring the other up to
> 127 to "ground".
>
> I believe in that case I would synthesize a std 127 volt circuit out of
> the control transformers secondary by connecting the lower voltage wire
> to the machines frame, along with the static ground wire in a short bit
> of romex & using the std color code where the black wire is the high
> side of the transformers secondary, feed it to a duplex or 4 plex to
> power the computer, monitor, and any other 120 volt only loads on the
> machine as long as the total load is within the ratings of the
> transformer.
>
> That should be 100% safe for everything.  And it should reduce the
> coupled noise just because its all bouncing in unison.
>
> Some of the noise coupling is coming into the 120 volt circuit from
> the "longitudinal" coupling of the windings un-avoidable capacitance,
> and grounding one side of it, and the loads static ground to the
> machines frame & ground should absorb a good share of it.
>
> In really obnoxious cases, a small, perhaps a .01 to .1 uF capacitor
> rated at least at 600 volts from the high side, black wire to the
> duplex, to the machines frame should gobble up the rest of it. And not
> just for S, I'd fuse the hot lead of that cap since a failure would
> take out the control transformer.  Fused at less than the transformer is
> rated of course since you want to blow the fuse instead of the
> transformer.
>
> That was my theory when I hooked this room up, and I have not lost a
> piece of gear during an electrical storm in over 10 years since I did
> it.  With the 50kw can that supplies 4 houses on the pole across the
> street, that pole has been nailed quite a few times, and I even got a
> grab the doorknob shock that jumped out of a wired keyboard once.  So I
> know this whole room full of electronics has bounced at least 25Kv. Not
> even a computer crash when it happened.
>
> Electrical shock is a weirdly defined thing. Below 20 micro-amps directly
> thru the heart, a currant so low you may not even feel it, is generally
> harmless, but at 20 micro-amps up to about 20 milli-amps it can disturb
> the beat, causing fibrillation and eventual death if no one removes the
> power or you from the source and applies the defibber paddles.
>
> Above 20 milli-amps, the survival rate is better because the heart is
> frozen, and when the currant is removed, and it hasn't been frozen so
> long you are brain dead from lack of oxygen, then the heart will often
> start back as if nothing has happened.
>
> Your trivia factoid for the day. :)
>
> My ex had a cousin that I met once in the 1970's after he had stuck an
> alu ladder he was carrying into a low hanging 7200 volt line. Lost part
> of a foot, and the shoulder blade and arm the ladder was laying on.
> Never was the sharpest tack in the box, but I'd have guessed him at an
> IQ of 105 to 110 or so after the event.  Some surgery, a specially built
> boot and a while to heal, which he was still doing when I met him at
> some sort of a family doin's, but by now he's probably taken over the
> painting business his father started 50+ years ago and run it, if not
> retired from it. That was a "few" thousand  days ago. :)  The ex left 31
> years ago, ending any excuse I had to keep track of someone in Wisconsin
> I only met once.
>
>> On 12/31/2015 5:50 PM, Gene Heskett wrote:
>>> On Thursday 31 December 2015 16:20:40 John Thornton wrote:
 On the 120v side if I measure from the hot to the ground I get 79
 volts, if I measure from hot to neutral I get the expected 128v...
 what is that telling me?

 JT
>>> My first guess is that the Bridgeport itself, is not grounded.  It
>>> really should be, just to keep it from becoming lethally hot when
>>> somethings insulation 

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 01/01/2016 05:47 PM, Dave Cole wrote:
> That's done all of the time.   In fact it is part of the NEC (National 
> Electric Code) that is followed (for the most part) in the US.
> Pretty much every house in the US is wired like that.  (I'm not making 
> this stuff up.  :-) )

I agree with the connection at power entry in the house. That is quite a
different story. That is actually the same here in EU (most countries).

I think that we should separate two things:
- house installation
- machine wiring

House installation is pretty much standardized with a lot of rules and
reasons. Specifically to ensure referencing and protection.

Machine wiring is different in that you can have scenarios where
references are moved, especially in a 2-phase system where you are not
using the neutral, which is the scenario we have here.


> Now, if you don't want to do that inside the panel for some reason 
> (which I might have missed), that may be a different story.
> I'm just saying that is standard practice in the US and on the European 
> machines I have worked on as well.

The reason for /not/ connecting the ground on a secondary winding is to
prevent a capacitively coupled ground path. Especially if you cannot
guarantee a 100% balanced primary-to-secondary side wrt. ground (*).

What happens is that there will be a current in the ground connection
which causes an imbalanced current on the primary side (remember:
primary is 2-phase circuit without neutral reference). This is a
differential current discrepancy on the primary side. If you have an RCD
(which you should), then it can or will trip due to the current imbalance.


(*) and from the example measurements presented by JT, we can be assured
that there is an imbalance, as seen from the phase shift causing a
difference in voltage measured wrt. ground on the secondary.


> There are a lot of good reasons to tie one leg the transformer to ground 
> besides to establish the safety ground and neutral as is common on the US.
> Intermittent faults to ground, with an ungrounded system, can cause the 
> secondary of the transformer to fly way above absolute ground causing 
> connected devices, or the transformer to suffer from insulation 
> breakdowns.   That's the extreme, but it can happen.

Actually, the secondary should normally be floating. Most transformer
setups are to ensure galvanic separation and that means you may never
connect neutral to the secondary side.

Connecting ground on a secondary is a different scenario, where you most
often see the 0V (DC) potential connected to protective ground. This is
often done in the PC's power supply. The 0V (DC) to protective ground
connection prevents the scenario to which you refer to.

The 0V (DC) to protective ground connection is repeated in many devices,
which have both power and signal connections. This gives rise to
ground-loops, which are to be prevented at all times and it is the cause
of the whole thread.


> One of way too many references on the web.
> http://ecmweb.com/bonding-amp-grounding/basics-bonding-and-grounding-transformers

It looks like the link is about a 3-phase system, where you would
connect the center point in a star-configured secondary to ground. That
is a different scenario.



-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[andy pugh]

On 1 January 2016 at 17:29, Bertho Stultiens  wrote:
> The reason for /not/ connecting the ground on a secondary winding is to
> prevent a capacitively coupled ground path.

Another reason is that if you connect either secondary winding end  to
ground using body parts then nothing bad happens. This is the point of
an isolation transformer.
If there is an isolation transformer fitted in the machine then
grounding one of its terminals makes it pointless.

-- 
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Gene Heskett]

On Friday 01 January 2016 07:00:31 John Thornton wrote:

> Hi Gene,
>
> The frame is most solidly grounded. I'll do the tests in a bit. Keep
> in mind that I have a 240v to 120v step down transformer to supply the
> 120v not a normal house circuit. Again an effort to kill the noise.
> Which by the way I'm running 2.7 now after changing the wires on the
> limit/home switches to twisted pair shielded wire. I've attached the
> VFD side wiring diagram. I assume the connection is through the
> neutral bonding screw at the panel because the step down transformer
> is isolated from ground.
>
> Happy New Year to you too.
>
> JT

So this then was my 2nd guess, is the capacitative interwinding coupling 
in that transformer capable of supplying a very few microamps of actual 
current, probably less than 1 or 2. With no loads plugged in, you could 
connect either of the output phases of that transformer to machine 
frame "ground" without any fireworks which would bring the other up to 
127 to "ground".

I believe in that case I would synthesize a std 127 volt circuit out of 
the control transformers secondary by connecting the lower voltage wire 
to the machines frame, along with the static ground wire in a short bit 
of romex & using the std color code where the black wire is the high 
side of the transformers secondary, feed it to a duplex or 4 plex to 
power the computer, monitor, and any other 120 volt only loads on the 
machine as long as the total load is within the ratings of the 
transformer.

That should be 100% safe for everything.  And it should reduce the 
coupled noise just because its all bouncing in unison.

Some of the noise coupling is coming into the 120 volt circuit from 
the "longitudinal" coupling of the windings un-avoidable capacitance, 
and grounding one side of it, and the loads static ground to the 
machines frame & ground should absorb a good share of it.

In really obnoxious cases, a small, perhaps a .01 to .1 uF capacitor 
rated at least at 600 volts from the high side, black wire to the 
duplex, to the machines frame should gobble up the rest of it. And not 
just for S, I'd fuse the hot lead of that cap since a failure would 
take out the control transformer.  Fused at less than the transformer is 
rated of course since you want to blow the fuse instead of the 
transformer.

That was my theory when I hooked this room up, and I have not lost a 
piece of gear during an electrical storm in over 10 years since I did 
it.  With the 50kw can that supplies 4 houses on the pole across the 
street, that pole has been nailed quite a few times, and I even got a 
grab the doorknob shock that jumped out of a wired keyboard once.  So I 
know this whole room full of electronics has bounced at least 25Kv. Not 
even a computer crash when it happened.

Electrical shock is a weirdly defined thing. Below 20 micro-amps directly 
thru the heart, a currant so low you may not even feel it, is generally 
harmless, but at 20 micro-amps up to about 20 milli-amps it can disturb 
the beat, causing fibrillation and eventual death if no one removes the 
power or you from the source and applies the defibber paddles.

Above 20 milli-amps, the survival rate is better because the heart is 
frozen, and when the currant is removed, and it hasn't been frozen so 
long you are brain dead from lack of oxygen, then the heart will often 
start back as if nothing has happened.

Your trivia factoid for the day. :)

My ex had a cousin that I met once in the 1970's after he had stuck an 
alu ladder he was carrying into a low hanging 7200 volt line. Lost part 
of a foot, and the shoulder blade and arm the ladder was laying on.  
Never was the sharpest tack in the box, but I'd have guessed him at an 
IQ of 105 to 110 or so after the event.  Some surgery, a specially built 
boot and a while to heal, which he was still doing when I met him at 
some sort of a family doin's, but by now he's probably taken over the 
painting business his father started 50+ years ago and run it, if not 
retired from it. That was a "few" thousand  days ago. :)  The ex left 31 
years ago, ending any excuse I had to keep track of someone in Wisconsin 
I only met once.

> On 12/31/2015 5:50 PM, Gene Heskett wrote:
> > On Thursday 31 December 2015 16:20:40 John Thornton wrote:
> >> On the 120v side if I measure from the hot to the ground I get 79
> >> volts, if I measure from hot to neutral I get the expected 128v...
> >> what is that telling me?
> >>
> >> JT
> >
> > My first guess is that the Bridgeport itself, is not grounded.  It
> > really should be, just to keep it from becoming lethally hot when
> > somethings insulation fails.  Generally speaking, if I can measure
> > more than a volt between neutral and the static ground, it concerns
> > me UNLESS its a wild phase , which I don't believe you have since
> > its not a 3 phase circuit.
> >
> > TBE if something is running that uses that neutral you might see
> > more volts, but I'd re-measure after turning 

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 01/01/2016 05:13 PM, Dave Cole wrote:
> Anytime you have a 120 volt source for computer, misc power etc, you 
> need to declare one side of the 120 vac winding the neutral (white wire) 
> and tie that terminal to the machine frame.
> It similar to what is required at the service entrance of your house.  
> The neutral is always tied to the ground at the entrance box.   
> Oftentimes they drive  a screw through the neutral buss bar in the 
> service entrance box into the box sheetmetal and then tie a green or 
> bare copper ground wire to the same neutral buss bar and run that to a 
> metal water pipe or ground rod.

You should never tie a secondary winding of a transformer to ground. The
transformer makes the secondary float wrt. the primary and that is just
fine.

In this scenario, you would create a (capacitive) feed-through from the
transformer to ground because the primary is not referenced at ground.
The primary has two phases attached, which creates a virtual circuit at
the primary side.

The difficulty here is that you must take account for the floating
references, which make most of the things you measure local phenomena.
Once you go through the transformer, your reference to the primary line
input is lost and you must not try to reestablish it. It would only make
things bad and worse.


-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Jon Elson]

On 01/01/2016 06:02 AM, John Thornton wrote:
> Hi Jon,
>
> So tie say the 48v side to ground to create the neutral? I 
> attached the drawing of what I have so far on the VFD side.
>
With power off, use an Ohmmeter to verify the secondary is 
isolated from the frame.  If so, tie either end to ground.  
If NOT, then further investigation is required.
> Happy New year to you and I hope you stayed dry during the 
> recent monsoon we got.
>
It was fine here, but lots of highways closed.  My mother in 
law's house had some basement leakage.  During the strongest 
rain, we had a drip where the furnace flue goes through the 
roof.

Jon

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Kirk Wallace]

On 01/01/2016 09:29 AM, Bertho Stultiens wrote:
... snip

> Machine wiring is different in that you can have scenarios where
> references are moved, especially in a 2-phase system where you are not
> using the neutral, which is the scenario we have here.

... snip

My understanding is, and I could be wrong, that "two-phase" in reference 
to modern mains circuits does not exist. Circuits with two hot legs, L1 
and L2, are single phase and referenced to each other. Two phase used to 
be two legs that were 90 degrees apart, but is long gone.

https://en.wikipedia.org/wiki/Two-phase_electric_power

I had fits trying to understand how rotary three-phase converters worked 
until I purged the notion of the input being two-phase.

Two phase does exist for stepper motors.
https://en.wikipedia.org/wiki/Stepper_motor#Two-phase_stepper_motors

-- 
Kirk Wallace
http://www.wallacecompany.com/machine_shop/
http://www.wallacecompany.com/E45/

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Jon Elson]

On 12/31/2015 03:24 PM, John Thornton wrote:
> I went and checked the control transformer and one side is 48v to ground
> and the other side is 79v to ground. I guess I was confused by that.
>
Do you have a ground connected to that winding?  If not, 
then the capacitance of that winding to other windings and 
the core will set what AC potential you get at each end.  
I'm guessing you have a totally floating secondary, and this 
adds up to 127 VAC, which sounds right for a nominal 120 V 
output.  You can tie one end of the winding to frame ground, 
establishing a new neutral in the cabinet for the computer, 
etc. loads.

Jon

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

On the 120v side if I measure from the hot to the ground I get 79 volts, 
if I measure from hot to neutral I get the expected 128v... what is that 
telling me?

JT

On 12/25/2015 4:51 PM, John Thornton wrote:
> I think a fresh thread is in order for this ordeal.
>
> I'm starting at the plug... I dug up some 10-3 SO cord and wired the
> plug and brought that into the left cabinet. Landed the wires on some
> terminal blocks with the DIN rail bolted to the cabinet with star
> washers between the DIN rail and the cabinet. I also scraped the paint
> off the cabinet in that area. Ground terminal blocks surround the
> distribution terminal blocks (two blocks tied together). I'm also making
> a print of the wiring as I go along. So from the distribution blocks the
> 240v goes to the VFD filter and the control transformer. I have a second
> filter for the 120v side, should that go just after the control transformer?
>
> JT
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

I went and checked the control transformer and one side is 48v to ground 
and the other side is 79v to ground. I guess I was confused by that.

JT

On 12/25/2015 4:51 PM, John Thornton wrote:
> I think a fresh thread is in order for this ordeal.
>
> I'm starting at the plug... I dug up some 10-3 SO cord and wired the
> plug and brought that into the left cabinet. Landed the wires on some
> terminal blocks with the DIN rail bolted to the cabinet with star
> washers between the DIN rail and the cabinet. I also scraped the paint
> off the cabinet in that area. Ground terminal blocks surround the
> distribution terminal blocks (two blocks tied together). I'm also making
> a print of the wiring as I go along. So from the distribution blocks the
> 240v goes to the VFD filter and the control transformer. I have a second
> filter for the 120v side, should that go just after the control transformer?
>
> JT
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 12/31/2015 10:20 PM, John Thornton wrote:
> On the 120v side if I measure from the hot to the ground I get 79 volts, 
> if I measure from hot to neutral I get the expected 128v... what is that 
> telling me?

It tells you:
  (protective) Ground != Neutral

(protective) Ground is for protection, not to carry any return current.
(protective) Ground wires should never ever carry current.

Neutral is for return current.


The potential difference between the two is because the (protective)
ground may float with respect to neutral.

You *never* look at the potential wrt. (protective) ground for anything
else than to test for couplings. Never ever are measurements to be used
to calculate loads.

-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Gene Heskett]

On Thursday 31 December 2015 16:20:40 John Thornton wrote:

> On the 120v side if I measure from the hot to the ground I get 79
> volts, if I measure from hot to neutral I get the expected 128v...
> what is that telling me?
>
> JT

My first guess is that the Bridgeport itself, is not grounded.  It really 
should be, just to keep it from becoming lethally hot when somethings 
insulation fails.  Generally speaking, if I can measure more than a volt 
between neutral and the static ground, it concerns me UNLESS its a wild 
phase , which I don't believe you have since its not a 3 phase circuit.

TBE if something is running that uses that neutral you might see more 
volts, but I'd re-measure after turning whatever it was off.

As to the 79 volts, I would put a small light bulb (7.5 watt night lite) 
from the Bp frame to neutral to see if there is any real current, or its 
just capacitative coupling. If capacitative coupling, a 7.5 watt night 
light bulb will remain dark, and that voltage should drop to less than 1 
or 2 volts. If it lights up at all, and the voltage doesn't drop 
drastically, there really is a fault someplace.  I'd start disconnecting 
motors for starters.

Happy New Year John.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Jerry Scharf]

Hi,

RS232 is an old connection from terminals (DTE) to modems (DCE). at some
point, every wire in the 25 line cable had active signals.

To connect two DTEs together, you need a "null modem" crossover. The most
typical null modem does the following. (I will note the pin number on the
DB25 conector):

Exchanges RxD(3) and TxD (2)  on the two sides
Connects signal ground(7) on the two sides
Connects RTS(4) to CTS(5) on the same side
Connects DTR(20) on one side to both DCD(8) and DSR(6) on the other

The other signals are for things like synchronous modems and the like.

You can get a RS232 Breakout box like
http://www.altex.com/RS232-Breakout-Box-BRB-232-P140389.aspx
to debug things. This allows you to connect and disconnect signals, set
them to values...

Data lines are negative true and signalling lines are positive true.

Yes, I remember debugging 300 baud modems. Then again, people think I also
remember the dinosaurs. :)

jerry

On Tue, Dec 29, 2015 at 11:59 AM, John Thornton  wrote:

> An update, I got the serial isolator but it did not work out of the box.
> It had something about DTE and DCE that I didn't understand how to tell
> what the GS2 uses and can't find anything about DTE or DCE in the manual...
>
> JT
>
> On 12/25/2015 4:51 PM, John Thornton wrote:
> > I think a fresh thread is in order for this ordeal.
> >
> > I'm starting at the plug... I dug up some 10-3 SO cord and wired the
> > plug and brought that into the left cabinet. Landed the wires on some
> > terminal blocks with the DIN rail bolted to the cabinet with star
> > washers between the DIN rail and the cabinet. I also scraped the paint
> > off the cabinet in that area. Ground terminal blocks surround the
> > distribution terminal blocks (two blocks tied together). I'm also making
> > a print of the wiring as I go along. So from the distribution blocks the
> > 240v goes to the VFD filter and the control transformer. I have a second
> > filter for the 120v side, should that go just after the control
> transformer?
> >
> > JT
> >
> >
> --
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
>
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>



-- 
Jerry Scharf
FINsix IT
650.285.6361 w
650.279.7017 m
--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 12/29/2015 08:59 PM, John Thornton wrote:
> An update, I got the serial isolator but it did not work out of the box. 
> It had something about DTE and DCE that I didn't understand how to tell 
> what the GS2 uses and can't find anything about DTE or DCE in the manual...

DTE/DCE is whether you need to cross the Tx/Rx lines (straight or
cross-over cable).

In a three-wire serial connection you only have two options:
- straight cable (rx-rxd, tx-txd, gnd-gnd)
- cross-over cable (tx-rxd, rx-txd, gnd-gnd)

Most of these serial isolators are powered from the TX lines, so you
must have them connected correctly.

-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

An update, I got the serial isolator but it did not work out of the box. 
It had something about DTE and DCE that I didn't understand how to tell 
what the GS2 uses and can't find anything about DTE or DCE in the manual...

JT

On 12/25/2015 4:51 PM, John Thornton wrote:
> I think a fresh thread is in order for this ordeal.
>
> I'm starting at the plug... I dug up some 10-3 SO cord and wired the
> plug and brought that into the left cabinet. Landed the wires on some
> terminal blocks with the DIN rail bolted to the cabinet with star
> washers between the DIN rail and the cabinet. I also scraped the paint
> off the cabinet in that area. Ground terminal blocks surround the
> distribution terminal blocks (two blocks tied together). I'm also making
> a print of the wiring as I go along. So from the distribution blocks the
> 240v goes to the VFD filter and the control transformer. I have a second
> filter for the 120v side, should that go just after the control transformer?
>
> JT
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

I was in a plant and the maintenance guy was bitching about blowing up a 
plc he just hooked up and I asked him where he hooked it up... he showed 
me where the breaker was and it was on the 277 lighting circuit of a 3 
phase panel.

On 12/27/2015 9:25 PM, Dave Cole wrote:
> Well, if you ran a neutral to the BP what would you use it for ??  :-)
>
> It isn't required by the NEC.
>
> What you can't do is to tie a 120 VAC load between a hot wire and the
> protective ground (which JT is not doing ).
>
> I do a lot of machine wiring and I was redoing a machine for a major
> electrical manufacturer in the US (although this particular plant does
> hydraulics)
> and the plant maintenance nitwits tied a relay coil between a 480 volt
> hot leg and the protective ground because they did not have a neutral in
> the control cabinet and they had a 277 volt relay!  8-O
>
> I ripped out the added "circuitry" and wrote a note to the maintenance
> mgr and explained that if the protective ground wire had became
> disconnected from the power feed that the machine frame would become hot
> to ground through the 277 volt relay coil!
>
> Dave
>
>
> On 12/27/2015 6:21 PM, John Thornton wrote:
>> The VFD filter has no place to connect a neutral... only hots and ground.
>>
>> On 12/27/2015 5:10 PM, Gene Heskett wrote:
>>> On Sunday 27 December 2015 17:07:15 John Thornton wrote:
>>>
 I've built a bunch of automation machines for Briggs and Stratton and
 they never pull a neutral only 3 240v hots and a ground. We always
 have a control transformer for the 120v stuff... I have the same here
 now.
>>> After an hours searching thru it, and its the 1996 issue, a 240 volt
>>> single phase line w/o a neutral is legal if it goes only to that machine
>>> AND the machine was designed for that power configuration, eg is
>>> designed to run on 240 for everything.
>>>
>>> IOW if it goes anyplace else in the building besides that machine, it has
>>> to have a neutral too.  And of coarse grounded is a given.
>>>
>>> So in your case, you can utilize a 240-120 stepdown that is NOT an
>>> autoformer.  And from whats been said, that is what you are doing.
>>>
>>> However, speaking as a C.E.T., not having the neutral so that the filters
>>> you are installing can ship their noise back up that separate circuit,
>>> effectively isolated from what is supposed to be a nice quiet ground,
>>> does seem like it would put a lot of the absorbed noises into the
>>> grounding system. And unless putting the filters in fixes it, making me
>>> just a worry wart, I believe this may be much of your noise problem.
>>>
>>> Since we've come 19 years into the future since my copy of the NEC was
>>> put to bed & sold, with more efficient (and more noise sensitive) ways
>>> to do things now, I'd expect that a current copy of the NEC would more
>>> than likely have some additions designed to head off problems like this.
>>>
>>> Unfortunately a current copy is now at or somewhat north of a 120 dollar
>>> bill.
>>>
 On 12/27/2015 3:52 PM, Gene Heskett wrote:
> On Sunday 27 December 2015 16:17:20 John Thornton wrote:
>> well there is no neutral because it's a 240vac circuit only...
> The only reason there is not a neutral is that the wire was never
> pulled. And I am not sure that missing neutral is NEC kosher.  My
> copy is now 17 years old, so I think I'd check a newer one to be
> sure.  With it, you wouldn't need the stepdown and isolation tranny
> because you would then have a pair of 120 circuits available in the
> machine.  But those loads MUST return on the neutral, they cannot
> use the static ground.
>
>> On 12/27/2015 12:16 PM, Bruce Layne wrote:
>>> On 12/26/2015 06:51 PM, John Thornton wrote:
 There is no neutral in the machine, only L1 L2 and GND. The
 Neutral for the house is bonded to ground at the panels.
>>> Electrician's  Joke:
>>>
>>> Q: What's the difference between neutral and ground?
>>> A: About six inches.
>>>
>>> There's a very good reason the return current is carried on the
>>> neutral and the ground should not carry any current in normal
>>> circumstances, but we do need to understand that electrons don't
>>> care about our conventions.  They're just as happy returning via
>>> the ground wire.  They don't know that the green wire is off
>>> limits for all but emergency traffic.
>>>
>>> The concept of ground/neutral functional equivalence is also a
>>> real life saver for anyone who might otherwise consider standing
>>> barefoot on a basement floor while hot wiring any line powered AC
>>> circuit.
> Cheers, Gene Heskett
 --
  ___
 Emc-users mailing list
 Emc-users@lists.sourceforge.net
 https://lists.sourceforge.net/lists/listinfo/emc-users
>>> Cheers, Gene Heskett

Re: [Emc-users] Rewiring the BP

[Gene Heskett]

On Sunday 27 December 2015 13:16:17 Bruce Layne wrote:

> On 12/26/2015 06:51 PM, John Thornton wrote:
> > There is no neutral in the machine, only L1 L2 and GND. The Neutral
> > for the house is bonded to ground at the panels.
>
> Electrician's  Joke:
>
> Q: What's the difference between neutral and ground?
> A: About six inches.
>
> There's a very good reason the return current is carried on the
> neutral and the ground should not carry any current in normal
> circumstances, but we do need to understand that electrons don't care
> about our
> conventions.  They're just as happy returning via the ground wire. 
> They don't know that the green wire is off limits for all but
> emergency traffic.
>
> The concept of ground/neutral functional equivalence is also a real
> life saver for anyone who might otherwise consider standing barefoot
> on a basement floor while hot wiring any line powered AC circuit.

True Bruce, but in the event we stumble upon such a scene, we really do 
need to have a good stock of "here's your sign" signs to hand out. 
Before or after you use the signs dry wooden handle to knock them loose 
from the circuit being optional.  You can often tell the type by looking 
at their diagonal cutters jaws to see if they've been used to cut hot 
circuits. I once, way back in the dark ages, worked for an electrician 
who, when doing rework, had an old set of dime store cutters that he 
used to bite into the cable just to blow the fuse or breaker, then he'd 
go to the service and disconnect & tag the circuit he'd blown.  Much 
quicker than trying to trace it by killing one circuit at a time & 
waiting for his helper to yell that was it.  Sometimes it was a real 
trip, crawling around in an attic full of knob and ball wiring with that 
guy.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

well there is no neutral because it's a 240vac circuit only...

On 12/27/2015 12:16 PM, Bruce Layne wrote:
>
> On 12/26/2015 06:51 PM, John Thornton wrote:
>> There is no neutral in the machine, only L1 L2 and GND. The Neutral for
>> the house is bonded to ground at the panels.
> Electrician's  Joke:
>
> Q: What's the difference between neutral and ground?
> A: About six inches.
>
> There's a very good reason the return current is carried on the neutral
> and the ground should not carry any current in normal circumstances, but
> we do need to understand that electrons don't care about our
> conventions.  They're just as happy returning via the ground wire.  They
> don't know that the green wire is off limits for all but emergency traffic.
>
> The concept of ground/neutral functional equivalence is also a real life
> saver for anyone who might otherwise consider standing barefoot on a
> basement floor while hot wiring any line powered AC circuit.
>
>
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bruce Layne]

On 12/26/2015 06:51 PM, John Thornton wrote:
> There is no neutral in the machine, only L1 L2 and GND. The Neutral for
> the house is bonded to ground at the panels.

Electrician's  Joke:

Q: What's the difference between neutral and ground?
A: About six inches.

There's a very good reason the return current is carried on the neutral 
and the ground should not carry any current in normal circumstances, but 
we do need to understand that electrons don't care about our 
conventions.  They're just as happy returning via the ground wire.  They 
don't know that the green wire is off limits for all but emergency traffic.

The concept of ground/neutral functional equivalence is also a real life 
saver for anyone who might otherwise consider standing barefoot on a 
basement floor while hot wiring any line powered AC circuit.



--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

Except for underground rural power where every house has a pad mounted 
transformer due to the distance between houses (I love the distance).

I bonded the neutral to the ground at both panels in the shop/garage and 
the panel at the house. I have ground rods at the house and shop/garage. 
The panels are back to back in the shop/garage and both are connected to 
the ground rod just outside the shop/garage. I was told this is correct...

JT

On 12/26/2015 6:32 PM, John Kasunich wrote:
>
>
> The transformer is typically mounted on a pole and serves several houses.
> The neutral is connected to a ground rod at the base of the pole.  There
> are three wires from the pole to each house - L1, L2, and Neutral (no ground).
>
> Each house has a ground rod.  The neutral from the transformer, the
> house ground rod, a connection from the house cold water plumbing (if
> copper), the neutrals from all the receptacles, and the ground wires from
> all the receptacles are all tied together at a large bus bar in the main 
> panel.
>
> Other than the tie point in the main panel, neutral and ground are kept
> separated throughout the rest of the building, including through any sub-
> panels in garages, etc.
>
>
> John Kasunich
>


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

I've built a bunch of automation machines for Briggs and Stratton and 
they never pull a neutral only 3 240v hots and a ground. We always have 
a control transformer for the 120v stuff... I have the same here now.

On 12/27/2015 3:52 PM, Gene Heskett wrote:
> On Sunday 27 December 2015 16:17:20 John Thornton wrote:
>
>> well there is no neutral because it's a 240vac circuit only...
>>
> The only reason there is not a neutral is that the wire was never pulled.
> And I am not sure that missing neutral is NEC kosher.  My copy is now 17
> years old, so I think I'd check a newer one to be sure.  With it, you
> wouldn't need the stepdown and isolation tranny because you would then
> have a pair of 120 circuits available in the machine.  But those loads
> MUST return on the neutral, they cannot use the static ground.
>> On 12/27/2015 12:16 PM, Bruce Layne wrote:
>>> On 12/26/2015 06:51 PM, John Thornton wrote:
 There is no neutral in the machine, only L1 L2 and GND. The Neutral
 for the house is bonded to ground at the panels.
>>> Electrician's  Joke:
>>>
>>> Q: What's the difference between neutral and ground?
>>> A: About six inches.
>>>
>>> There's a very good reason the return current is carried on the
>>> neutral and the ground should not carry any current in normal
>>> circumstances, but we do need to understand that electrons don't
>>> care about our conventions.  They're just as happy returning via the
>>> ground wire.  They don't know that the green wire is off limits for
>>> all but emergency traffic.
>>>
>>> The concept of ground/neutral functional equivalence is also a real
>>> life saver for anyone who might otherwise consider standing barefoot
>>> on a basement floor while hot wiring any line powered AC circuit.
> Cheers, Gene Heskett


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Gene Heskett]

On Sunday 27 December 2015 18:21:33 John Thornton wrote:

> The VFD filter has no place to connect a neutral... only hots and
> ground.
>
Goody.  But if it works, hey!

> On 12/27/2015 5:10 PM, Gene Heskett wrote:
> > On Sunday 27 December 2015 17:07:15 John Thornton wrote:
> >> I've built a bunch of automation machines for Briggs and Stratton
> >> and they never pull a neutral only 3 240v hots and a ground. We
> >> always have a control transformer for the 120v stuff... I have the
> >> same here now.
> >
> > After an hours searching thru it, and its the 1996 issue, a 240 volt
> > single phase line w/o a neutral is legal if it goes only to that
> > machine AND the machine was designed for that power configuration,
> > eg is designed to run on 240 for everything.
> >
> > IOW if it goes anyplace else in the building besides that machine,
> > it has to have a neutral too.  And of coarse grounded is a given.
> >
> > So in your case, you can utilize a 240-120 stepdown that is NOT an
> > autoformer.  And from whats been said, that is what you are doing.
> >
> > However, speaking as a C.E.T., not having the neutral so that the
> > filters you are installing can ship their noise back up that
> > separate circuit, effectively isolated from what is supposed to be a
> > nice quiet ground, does seem like it would put a lot of the absorbed
> > noises into the grounding system. And unless putting the filters in
> > fixes it, making me just a worry wart, I believe this may be much of
> > your noise problem.
> >
> > Since we've come 19 years into the future since my copy of the NEC
> > was put to bed & sold, with more efficient (and more noise
> > sensitive) ways to do things now, I'd expect that a current copy of
> > the NEC would more than likely have some additions designed to head
> > off problems like this.
> >
> > Unfortunately a current copy is now at or somewhat north of a 120
> > dollar bill.
> >
> >> On 12/27/2015 3:52 PM, Gene Heskett wrote:
> >>> On Sunday 27 December 2015 16:17:20 John Thornton wrote:
>  well there is no neutral because it's a 240vac circuit only...
> >>>
> >>> The only reason there is not a neutral is that the wire was never
> >>> pulled. And I am not sure that missing neutral is NEC kosher.  My
> >>> copy is now 17 years old, so I think I'd check a newer one to be
> >>> sure.  With it, you wouldn't need the stepdown and isolation
> >>> tranny because you would then have a pair of 120 circuits
> >>> available in the machine.  But those loads MUST return on the
> >>> neutral, they cannot use the static ground.
> >>>
>  On 12/27/2015 12:16 PM, Bruce Layne wrote:
> > On 12/26/2015 06:51 PM, John Thornton wrote:
> >> There is no neutral in the machine, only L1 L2 and GND. The
> >> Neutral for the house is bonded to ground at the panels.
> >
> > Electrician's  Joke:
> >
> > Q: What's the difference between neutral and ground?
> > A: About six inches.
> >
> > There's a very good reason the return current is carried on the
> > neutral and the ground should not carry any current in normal
> > circumstances, but we do need to understand that electrons don't
> > care about our conventions.  They're just as happy returning via
> > the ground wire.  They don't know that the green wire is off
> > limits for all but emergency traffic.
> >
> > The concept of ground/neutral functional equivalence is also a
> > real life saver for anyone who might otherwise consider standing
> > barefoot on a basement floor while hot wiring any line powered
> > AC circuit.
> >>>
> >>> Cheers, Gene Heskett
> >>
> >> ---
> >>---  ___
> >> Emc-users mailing list
> >> Emc-users@lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/emc-users
> >
> > Cheers, Gene Heskett
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 12/28/2015 04:25 AM, Dave Cole wrote:
[snip]
> I do a lot of machine wiring and I was redoing a machine for a major 
> electrical manufacturer in the US (although this particular plant does 
> hydraulics)
> and the plant maintenance nitwits tied a relay coil between a 480 volt 
> hot leg and the protective ground because they did not have a neutral in 
> the control cabinet and they had a 277 volt relay!  8-O
> 
> I ripped out the added "circuitry" and wrote a note to the maintenance 
> mgr and explained that if the protective ground wire had became 
> disconnected from the power feed that the machine frame would become hot 
> to ground through the 277 volt relay coil!

Oh boy! Some never learn how this stuff works and how dangerous it can be.


For that matter; I learned, many many years ago, that the protective
ground (or "earth" as it is called here) is the first pin/wire that must
be connected and the last that is disconnected. Specifically with
disconnection it is regardless whether it is a connector or cable you
are pulling, the protection must always be the last to go.


-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Gene Heskett]

On Sunday 27 December 2015 16:17:20 John Thornton wrote:

> well there is no neutral because it's a 240vac circuit only...
>
The only reason there is not a neutral is that the wire was never pulled.  
And I am not sure that missing neutral is NEC kosher.  My copy is now 17 
years old, so I think I'd check a newer one to be sure.  With it, you 
wouldn't need the stepdown and isolation tranny because you would then 
have a pair of 120 circuits available in the machine.  But those loads 
MUST return on the neutral, they cannot use the static ground.
> On 12/27/2015 12:16 PM, Bruce Layne wrote:
> > On 12/26/2015 06:51 PM, John Thornton wrote:
> >> There is no neutral in the machine, only L1 L2 and GND. The Neutral
> >> for the house is bonded to ground at the panels.
> >
> > Electrician's  Joke:
> >
> > Q: What's the difference between neutral and ground?
> > A: About six inches.
> >
> > There's a very good reason the return current is carried on the
> > neutral and the ground should not carry any current in normal
> > circumstances, but we do need to understand that electrons don't
> > care about our conventions.  They're just as happy returning via the
> > ground wire.  They don't know that the green wire is off limits for
> > all but emergency traffic.
> >
> > The concept of ground/neutral functional equivalence is also a real
> > life saver for anyone who might otherwise consider standing barefoot
> > on a basement floor while hot wiring any line powered AC circuit.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Gene Heskett]

On Sunday 27 December 2015 17:07:15 John Thornton wrote:

> I've built a bunch of automation machines for Briggs and Stratton and
> they never pull a neutral only 3 240v hots and a ground. We always
> have a control transformer for the 120v stuff... I have the same here
> now.

After an hours searching thru it, and its the 1996 issue, a 240 volt 
single phase line w/o a neutral is legal if it goes only to that machine 
AND the machine was designed for that power configuration, eg is 
designed to run on 240 for everything.

IOW if it goes anyplace else in the building besides that machine, it has 
to have a neutral too.  And of coarse grounded is a given.

So in your case, you can utilize a 240-120 stepdown that is NOT an 
autoformer.  And from whats been said, that is what you are doing.

However, speaking as a C.E.T., not having the neutral so that the filters 
you are installing can ship their noise back up that separate circuit, 
effectively isolated from what is supposed to be a nice quiet ground, 
does seem like it would put a lot of the absorbed noises into the 
grounding system. And unless putting the filters in fixes it, making me 
just a worry wart, I believe this may be much of your noise problem.

Since we've come 19 years into the future since my copy of the NEC was 
put to bed & sold, with more efficient (and more noise sensitive) ways 
to do things now, I'd expect that a current copy of the NEC would more 
than likely have some additions designed to head off problems like this.

Unfortunately a current copy is now at or somewhat north of a 120 dollar 
bill.

> On 12/27/2015 3:52 PM, Gene Heskett wrote:
> > On Sunday 27 December 2015 16:17:20 John Thornton wrote:
> >> well there is no neutral because it's a 240vac circuit only...
> >
> > The only reason there is not a neutral is that the wire was never
> > pulled. And I am not sure that missing neutral is NEC kosher.  My
> > copy is now 17 years old, so I think I'd check a newer one to be
> > sure.  With it, you wouldn't need the stepdown and isolation tranny
> > because you would then have a pair of 120 circuits available in the
> > machine.  But those loads MUST return on the neutral, they cannot
> > use the static ground.
> >
> >> On 12/27/2015 12:16 PM, Bruce Layne wrote:
> >>> On 12/26/2015 06:51 PM, John Thornton wrote:
>  There is no neutral in the machine, only L1 L2 and GND. The
>  Neutral for the house is bonded to ground at the panels.
> >>>
> >>> Electrician's  Joke:
> >>>
> >>> Q: What's the difference between neutral and ground?
> >>> A: About six inches.
> >>>
> >>> There's a very good reason the return current is carried on the
> >>> neutral and the ground should not carry any current in normal
> >>> circumstances, but we do need to understand that electrons don't
> >>> care about our conventions.  They're just as happy returning via
> >>> the ground wire.  They don't know that the green wire is off
> >>> limits for all but emergency traffic.
> >>>
> >>> The concept of ground/neutral functional equivalence is also a
> >>> real life saver for anyone who might otherwise consider standing
> >>> barefoot on a basement floor while hot wiring any line powered AC
> >>> circuit.
> >
> > Cheers, Gene Heskett
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

The VFD filter has no place to connect a neutral... only hots and ground.

On 12/27/2015 5:10 PM, Gene Heskett wrote:
> On Sunday 27 December 2015 17:07:15 John Thornton wrote:
>
>> I've built a bunch of automation machines for Briggs and Stratton and
>> they never pull a neutral only 3 240v hots and a ground. We always
>> have a control transformer for the 120v stuff... I have the same here
>> now.
> After an hours searching thru it, and its the 1996 issue, a 240 volt
> single phase line w/o a neutral is legal if it goes only to that machine
> AND the machine was designed for that power configuration, eg is
> designed to run on 240 for everything.
>
> IOW if it goes anyplace else in the building besides that machine, it has
> to have a neutral too.  And of coarse grounded is a given.
>
> So in your case, you can utilize a 240-120 stepdown that is NOT an
> autoformer.  And from whats been said, that is what you are doing.
>
> However, speaking as a C.E.T., not having the neutral so that the filters
> you are installing can ship their noise back up that separate circuit,
> effectively isolated from what is supposed to be a nice quiet ground,
> does seem like it would put a lot of the absorbed noises into the
> grounding system. And unless putting the filters in fixes it, making me
> just a worry wart, I believe this may be much of your noise problem.
>
> Since we've come 19 years into the future since my copy of the NEC was
> put to bed & sold, with more efficient (and more noise sensitive) ways
> to do things now, I'd expect that a current copy of the NEC would more
> than likely have some additions designed to head off problems like this.
>
> Unfortunately a current copy is now at or somewhat north of a 120 dollar
> bill.
>
>> On 12/27/2015 3:52 PM, Gene Heskett wrote:
>>> On Sunday 27 December 2015 16:17:20 John Thornton wrote:
 well there is no neutral because it's a 240vac circuit only...
>>> The only reason there is not a neutral is that the wire was never
>>> pulled. And I am not sure that missing neutral is NEC kosher.  My
>>> copy is now 17 years old, so I think I'd check a newer one to be
>>> sure.  With it, you wouldn't need the stepdown and isolation tranny
>>> because you would then have a pair of 120 circuits available in the
>>> machine.  But those loads MUST return on the neutral, they cannot
>>> use the static ground.
>>>
 On 12/27/2015 12:16 PM, Bruce Layne wrote:
> On 12/26/2015 06:51 PM, John Thornton wrote:
>> There is no neutral in the machine, only L1 L2 and GND. The
>> Neutral for the house is bonded to ground at the panels.
> Electrician's  Joke:
>
> Q: What's the difference between neutral and ground?
> A: About six inches.
>
> There's a very good reason the return current is carried on the
> neutral and the ground should not carry any current in normal
> circumstances, but we do need to understand that electrons don't
> care about our conventions.  They're just as happy returning via
> the ground wire.  They don't know that the green wire is off
> limits for all but emergency traffic.
>
> The concept of ground/neutral functional equivalence is also a
> real life saver for anyone who might otherwise consider standing
> barefoot on a basement floor while hot wiring any line powered AC
> circuit.
>>> Cheers, Gene Heskett
>> --
>>  ___
>> Emc-users mailing list
>> Emc-users@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/emc-users
>
> Cheers, Gene Heskett


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Ralph Stirling]

That would be a three-phase delta configuration, if it has three
240v hot lines.  Delta wiring has no neutral, and it is 240v
line-to-line.  Three-phase wye connection has a neutral, and
it is 120v line-to-neutral, and 208v line-to-line.

-- Ralph

From: John Thornton [j...@gnipsel.com]
Sent: Sunday, December 27, 2015 2:07 PM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] Rewiring the BP

I've built a bunch of automation machines for Briggs and Stratton and
they never pull a neutral only 3 240v hots and a ground. We always have
a control transformer for the 120v stuff... I have the same here now.

On 12/27/2015 3:52 PM, Gene Heskett wrote:
> On Sunday 27 December 2015 16:17:20 John Thornton wrote:
>
>> well there is no neutral because it's a 240vac circuit only...
>>
> The only reason there is not a neutral is that the wire was never pulled.
> And I am not sure that missing neutral is NEC kosher.  My copy is now 17
> years old, so I think I'd check a newer one to be sure.  With it, you
> wouldn't need the stepdown and isolation tranny because you would then
> have a pair of 120 circuits available in the machine.  But those loads
> MUST return on the neutral, they cannot use the static ground.
>> On 12/27/2015 12:16 PM, Bruce Layne wrote:
>>> On 12/26/2015 06:51 PM, John Thornton wrote:
>>>> There is no neutral in the machine, only L1 L2 and GND. The Neutral
>>>> for the house is bonded to ground at the panels.
>>> Electrician's  Joke:
>>>
>>> Q: What's the difference between neutral and ground?
>>> A: About six inches.
>>>
>>> There's a very good reason the return current is carried on the
>>> neutral and the ground should not carry any current in normal
>>> circumstances, but we do need to understand that electrons don't
>>> care about our conventions.  They're just as happy returning via the
>>> ground wire.  They don't know that the green wire is off limits for
>>> all but emergency traffic.
>>>
>>> The concept of ground/neutral functional equivalence is also a real
>>> life saver for anyone who might otherwise consider standing barefoot
>>> on a basement floor while hot wiring any line powered AC circuit.
> Cheers, Gene Heskett


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Gene Heskett]

On Sunday 27 December 2015 17:07:15 John Thornton wrote:

> I've built a bunch of automation machines for Briggs and Stratton and
> they never pull a neutral only 3 240v hots and a ground. We always
> have a control transformer for the 120v stuff... I have the same here
> now.
>
That would also work as long as the machine frames are grounded, and a 
control transformer is used for the 120 volt loads. But my curiosity is 
aroused so I'll drag my copy of the NEC down & read a while.  Later.

> On 12/27/2015 3:52 PM, Gene Heskett wrote:
> > On Sunday 27 December 2015 16:17:20 John Thornton wrote:
> >> well there is no neutral because it's a 240vac circuit only...
> >
> > The only reason there is not a neutral is that the wire was never
> > pulled. And I am not sure that missing neutral is NEC kosher.  My
> > copy is now 17 years old, so I think I'd check a newer one to be
> > sure.  With it, you wouldn't need the stepdown and isolation tranny
> > because you would then have a pair of 120 circuits available in the
> > machine.  But those loads MUST return on the neutral, they cannot
> > use the static ground.
> >
> >> On 12/27/2015 12:16 PM, Bruce Layne wrote:
> >>> On 12/26/2015 06:51 PM, John Thornton wrote:
>  There is no neutral in the machine, only L1 L2 and GND. The
>  Neutral for the house is bonded to ground at the panels.
> >>>
> >>> Electrician's  Joke:
> >>>
> >>> Q: What's the difference between neutral and ground?
> >>> A: About six inches.
> >>>
> >>> There's a very good reason the return current is carried on the
> >>> neutral and the ground should not carry any current in normal
> >>> circumstances, but we do need to understand that electrons don't
> >>> care about our conventions.  They're just as happy returning via
> >>> the ground wire.  They don't know that the green wire is off
> >>> limits for all but emergency traffic.
> >>>
> >>> The concept of ground/neutral functional equivalence is also a
> >>> real life saver for anyone who might otherwise consider standing
> >>> barefoot on a basement floor while hot wiring any line powered AC
> >>> circuit.
> >
> > Cheers, Gene Heskett
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Dave Cole]

Well, if you ran a neutral to the BP what would you use it for ??  :-)

It isn't required by the NEC.

What you can't do is to tie a 120 VAC load between a hot wire and the 
protective ground (which JT is not doing ).

I do a lot of machine wiring and I was redoing a machine for a major 
electrical manufacturer in the US (although this particular plant does 
hydraulics)
and the plant maintenance nitwits tied a relay coil between a 480 volt 
hot leg and the protective ground because they did not have a neutral in 
the control cabinet and they had a 277 volt relay!  8-O

I ripped out the added "circuitry" and wrote a note to the maintenance 
mgr and explained that if the protective ground wire had became 
disconnected from the power feed that the machine frame would become hot 
to ground through the 277 volt relay coil!

Dave


On 12/27/2015 6:21 PM, John Thornton wrote:
> The VFD filter has no place to connect a neutral... only hots and ground.
>
> On 12/27/2015 5:10 PM, Gene Heskett wrote:
>> On Sunday 27 December 2015 17:07:15 John Thornton wrote:
>>
>>> I've built a bunch of automation machines for Briggs and Stratton and
>>> they never pull a neutral only 3 240v hots and a ground. We always
>>> have a control transformer for the 120v stuff... I have the same here
>>> now.
>> After an hours searching thru it, and its the 1996 issue, a 240 volt
>> single phase line w/o a neutral is legal if it goes only to that machine
>> AND the machine was designed for that power configuration, eg is
>> designed to run on 240 for everything.
>>
>> IOW if it goes anyplace else in the building besides that machine, it has
>> to have a neutral too.  And of coarse grounded is a given.
>>
>> So in your case, you can utilize a 240-120 stepdown that is NOT an
>> autoformer.  And from whats been said, that is what you are doing.
>>
>> However, speaking as a C.E.T., not having the neutral so that the filters
>> you are installing can ship their noise back up that separate circuit,
>> effectively isolated from what is supposed to be a nice quiet ground,
>> does seem like it would put a lot of the absorbed noises into the
>> grounding system. And unless putting the filters in fixes it, making me
>> just a worry wart, I believe this may be much of your noise problem.
>>
>> Since we've come 19 years into the future since my copy of the NEC was
>> put to bed & sold, with more efficient (and more noise sensitive) ways
>> to do things now, I'd expect that a current copy of the NEC would more
>> than likely have some additions designed to head off problems like this.
>>
>> Unfortunately a current copy is now at or somewhat north of a 120 dollar
>> bill.
>>
>>> On 12/27/2015 3:52 PM, Gene Heskett wrote:
 On Sunday 27 December 2015 16:17:20 John Thornton wrote:
> well there is no neutral because it's a 240vac circuit only...
 The only reason there is not a neutral is that the wire was never
 pulled. And I am not sure that missing neutral is NEC kosher.  My
 copy is now 17 years old, so I think I'd check a newer one to be
 sure.  With it, you wouldn't need the stepdown and isolation tranny
 because you would then have a pair of 120 circuits available in the
 machine.  But those loads MUST return on the neutral, they cannot
 use the static ground.

> On 12/27/2015 12:16 PM, Bruce Layne wrote:
>> On 12/26/2015 06:51 PM, John Thornton wrote:
>>> There is no neutral in the machine, only L1 L2 and GND. The
>>> Neutral for the house is bonded to ground at the panels.
>> Electrician's  Joke:
>>
>> Q: What's the difference between neutral and ground?
>> A: About six inches.
>>
>> There's a very good reason the return current is carried on the
>> neutral and the ground should not carry any current in normal
>> circumstances, but we do need to understand that electrons don't
>> care about our conventions.  They're just as happy returning via
>> the ground wire.  They don't know that the green wire is off
>> limits for all but emergency traffic.
>>
>> The concept of ground/neutral functional equivalence is also a
>> real life saver for anyone who might otherwise consider standing
>> barefoot on a basement floor while hot wiring any line powered AC
>> circuit.
 Cheers, Gene Heskett
>>> --
>>>  ___
>>> Emc-users mailing list
>>> Emc-users@lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/emc-users
>> Cheers, Gene Heskett
>
> --
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users

--
___

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 12/26/2015 07:36 PM, John Thornton wrote:
> You misunderstand, all those components are internally grounded I did 
> not ground any of them. I just showed that the shell on each component 
> is bonded to the ground connection on each device.

Ok, now the real question is whether you can see the difference wrt. to
my drawing.

The trick is that there should never ever be two or more paths for the
current to flow, even if it is just an earth connection (or GND for that
matter).

The isolation barrier I drew is the low-to-high-power separation. It
should be kept physically separated everywhere until you join the power
and earth connections at the power supply input.

The real problem I see is the connection of the VFD controller to the
computer's serial port. Apparently, the computer and the VFD controller
both have the GND connected internally to earth.

I am pretty sure that the computer's GND is connected to the earth
(chassis) of the computer (most PCs have).

The VFD controller probably has the same connection, where the modbus
serial port's GND is connected to the VFD controller's earth (chassis).

If so, then you need to break that loop by electrically isolating the
serial port.

-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 12/26/2015 08:09 PM, John Thornton wrote:
> I found this on amazon
> http://www.amazon.com/UT-211-Port-powered-Mini-size-PhotoElectric-Isolator/dp/B00GI9GS58/ref=sr_1_3?ie=UTF8=1451156759=8-3=serial+isolator

That is "port-powered", which may or may not work in your case. It
depends on which pins it uses to get its own power. I suggest an
externally powered version.


> Not sure how I might isolate the VFD from the chassis at this moment. 
> Well I could machine some delrin standoffs... I have a machine shop.

No problem. If you ensure that the chassis connection is firm and
electrically sound, then you just ommit the earth wire (my comment in
the drawing).

The volume and interconnections in the chassis are often good enough to
work as is.

You must make sure that all joints in the chassis are electrically
connected. That is why you often see that (short) earth-wire from one
part connecting the next part.


> I will need the control transformer to get power for the monitor or just 
> plug the monitor into the wall outlet and power the PC with 240v?

The monitor is on the computer side of the isolation barrier, so you
want to have it connected to the 240V where the computer gets its power.


-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 12/26/2015 08:19 PM, Bertho Stultiens wrote:
>> Not sure how I might isolate the VFD from the chassis at this moment. 
>> Well I could machine some delrin standoffs... I have a machine shop.
> 
> No problem. If you ensure that the chassis connection is firm and
> electrically sound, then you just ommit the earth wire (my comment in
> the drawing).

One more comment. If you are unsure that the internal earth/chassis
connection in the VFD controller holds, then you usually see a
connection as seen in the attached image. A short thick wire is run from
the earth screw connection to one of the chassis mounting bolts.


-- 
Greetings Bertho

(disclaimers are disclaimed)
--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Rafael]

On 12/26/2015 07:16 AM, John Thornton wrote:
> I just checked the ground to housing on the VFD filter, VFD, computer,
> and the smaller filter and they are all internally connected to ground.
> The VFD is controlled via modbus so I don't know how to check that cable
> (which is just a phone cable with a phone jack on one end and a DB9 on

Phone cable? Can you try to replace it with Cat-5 or a better twisted 
pairs cable?

> the other end to connect to the computers serial port, it's a Automation
> Direct cable not home made.

There is one other thing you might want to try, install ferrite core on 
power or other cables. It takes a lot of RF noise out. Search for 
"Ferrite Core Cord Noise Suppressor"

>
> Is injection to the mains coming back to the machine somehow?
>
> JT
>

I opened older power supply for 1U computer to remove the dust recently. 
I'm glad I did. Just looking at it, I could tell that there were 3 bad 
3300uF capacitors. Their tops were not flat. PSU still worked with small 
motherboard and one disk drive but the power was not clean for sure.

It is possible that you have a similar problem, i.e. old electrolytic 
caps in your VFD or power supply. Very critical in analog circuits.

Electrolytic caps are the most unstable electronic components and need 
to be replaced in old equipment. Some large caps can be refurbished but 
that's an extreme situation in very old computer restoration efforts.

Merry Christmas,

-- 
Rafael

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

I have a large ferrite bracelet for the output of the VFD to the spindle 
motor.

The computer is fairly new...

I have some Cat-5 and Cat-6 cable and the DB9 looks like a solder type 
shell.

JT

On 12/26/2015 11:53 AM, Rafael wrote:
> On 12/26/2015 07:16 AM, John Thornton wrote:
>> I just checked the ground to housing on the VFD filter, VFD, computer,
>> and the smaller filter and they are all internally connected to ground.
>> The VFD is controlled via modbus so I don't know how to check that cable
>> (which is just a phone cable with a phone jack on one end and a DB9 on
> Phone cable? Can you try to replace it with Cat-5 or a better twisted
> pairs cable?
>
>> the other end to connect to the computers serial port, it's a Automation
>> Direct cable not home made.
> There is one other thing you might want to try, install ferrite core on
> power or other cables. It takes a lot of RF noise out. Search for
> "Ferrite Core Cord Noise Suppressor"
>
>> Is injection to the mains coming back to the machine somehow?
>>
>> JT
>>
> I opened older power supply for 1U computer to remove the dust recently.
> I'm glad I did. Just looking at it, I could tell that there were 3 bad
> 3300uF capacitors. Their tops were not flat. PSU still worked with small
> motherboard and one disk drive but the power was not clean for sure.
>
> It is possible that you have a similar problem, i.e. old electrolytic
> caps in your VFD or power supply. Very critical in analog circuits.
>
> Electrolytic caps are the most unstable electronic components and need
> to be replaced in old equipment. Some large caps can be refurbished but
> that's an extreme situation in very old computer restoration efforts.
>
> Merry Christmas,
>


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

You misunderstand, all those components are internally grounded I did 
not ground any of them. I just showed that the shell on each component 
is bonded to the ground connection on each device.

On 12/26/2015 12:05 PM, Bertho Stultiens wrote:
> On 12/26/2015 04:33 PM, John Thornton wrote:
>> The drawing so far as I understand it.
> Ok, that is only part of the situation.
>
> I see that you have the spindle both go to earth via the chassis and
> then run a wire to the VFD controller's GND, which then has its chassis
> connected to earth. The same you have with the filter.
>
> These dual connections are possibly earth-loops. However, from your
> other comment, you may be confusing the term "earth" and "ground" and
> how those relate to the different devices and connections.
>
> It is a real pain that different manufacturers call one and the same
> thing differently. It is up to the user to know which is which.
>
>
> With a few assumptions, see my attached drawing.
>
>
>
>> I just checked the ground to housing on the VFD filter, VFD,
>> computer, and the smaller filter and they are all internally
>> connected to ground. The VFD is controlled via modbus so I don't know
>> how to check that cable (which is just a phone cable with a phone
>> jack on one end and a DB9 on the other end to connect to the
>> computers serial port, it's a Automation Direct cable not home made.
> It sounds like you have a ground-loop.
>
> Modbus is the protocol, which is connected using a serial interface. If
> the serial interface is not isolated, then you are in trouble.
>
>
>> Is injection to the mains coming back to the machine somehow?
> Yes and no. With a ground-loop, you never know what is happening and you
> are basically screwed.
>
>
>
>
> --
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

I found this on amazon

http://www.amazon.com/UT-211-Port-powered-Mini-size-PhotoElectric-Isolator/dp/B00GI9GS58/ref=sr_1_3?ie=UTF8=1451156759=8-3=serial+isolator

Not sure how I might isolate the VFD from the chassis at this moment. 
Well I could machine some delrin standoffs... I have a machine shop.

I will need the control transformer to get power for the monitor or just 
plug the monitor into the wall outlet and power the PC with 240v?

JT

On 12/26/2015 12:51 PM, Bertho Stultiens wrote:
> On 12/26/2015 07:36 PM, John Thornton wrote:
>> You misunderstand, all those components are internally grounded I did
>> not ground any of them. I just showed that the shell on each component
>> is bonded to the ground connection on each device.
> Ok, now the real question is whether you can see the difference wrt. to
> my drawing.
>
> The trick is that there should never ever be two or more paths for the
> current to flow, even if it is just an earth connection (or GND for that
> matter).
>
> The isolation barrier I drew is the low-to-high-power separation. It
> should be kept physically separated everywhere until you join the power
> and earth connections at the power supply input.
>
> The real problem I see is the connection of the VFD controller to the
> computer's serial port. Apparently, the computer and the VFD controller
> both have the GND connected internally to earth.
>
> I am pretty sure that the computer's GND is connected to the earth
> (chassis) of the computer (most PCs have).
>
> The VFD controller probably has the same connection, where the modbus
> serial port's GND is connected to the VFD controller's earth (chassis).
>
> If so, then you need to break that loop by electrically isolating the
> serial port.
>


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[Bertho Stultiens]

On 12/26/2015 08:19 PM, Bertho Stultiens wrote:
> On 12/26/2015 08:09 PM, John Thornton wrote:
>> I found this on amazon
>> http://www.amazon.com/UT-211-Port-powered-Mini-size-PhotoElectric-Isolator/dp/B00GI9GS58/ref=sr_1_3?ie=UTF8=1451156759=8-3=serial+isolator
> 
> That is "port-powered", which may or may not work in your case. It
> depends on which pins it uses to get its own power. I suggest an
> externally powered version.

Well, replying to myself here... It looks like those port-powered
versions should work. Thay are at least a lot cheaper than others, so
that may be the easiest way to test without burning your wallet.

Ebay seems to have some even cheaper.

-- 
Greetings Bertho

(disclaimers are disclaimed)

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

I'm assuming I can just screw the port powered isolator to the PC port 
and run a shielded cable from the VFD to the isolator?

On 12/26/2015 1:40 PM, Bertho Stultiens wrote:
> On 12/26/2015 08:19 PM, Bertho Stultiens wrote:
>>> Not sure how I might isolate the VFD from the chassis at this moment.
>>> Well I could machine some delrin standoffs... I have a machine shop.
>> No problem. If you ensure that the chassis connection is firm and
>> electrically sound, then you just ommit the earth wire (my comment in
>> the drawing).
> One more comment. If you are unsure that the internal earth/chassis
> connection in the VFD controller holds, then you usually see a
> connection as seen in the attached image. A short thick wire is run from
> the earth screw connection to one of the chassis mounting bolts.
>
>
>
>
> --
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users

--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Rewiring the BP

[John Thornton]

Ok that is easy to do, I have some huge stranded ground wire from a CT 
scanner... I've attached my updated drawing of the VFD panel.


The monitor can only run on 120v so it is necessary to transform from 
240 to 120 for the PC and monitor.


JT

On 12/26/2015 1:40 PM, Bertho Stultiens wrote:

On 12/26/2015 08:19 PM, Bertho Stultiens wrote:

Not sure how I might isolate the VFD from the chassis at this moment.
Well I could machine some delrin standoffs... I have a machine shop.

No problem. If you ensure that the chassis connection is firm and
electrically sound, then you just ommit the earth wire (my comment in
the drawing).

One more comment. If you are unsure that the internal earth/chassis
connection in the VFD controller holds, then you usually see a
connection as seen in the attached image. A short thick wire is run from
the earth screw connection to one of the chassis mounting bolts.




--


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users


--
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users