The problem is there are no low impedance ground available. The mains power
cable ground is not low impedance at high frequency and the common mode voltage
of inverters will couple a high frequency current into the ground cable. The
trick usually used is to isolate logical ground and increase
Przemek, the shield picks up stray energy from the suroundings. The
inside of it is a faraday cage and free of electric fields, which is
what we aim at. Now, as the shield has picked up the noise energy,
(re)converting electromagnetic field energy to real voltage and current,
it must get rid
.
Steve Stallings
-Original Message-
From: Przemek Klosowski [mailto:przemek.klosow...@gmail.com]
Sent: Wednesday, March 18, 2015 11:12 AM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] VFD causing limits to trip. Huh?
On Mon, Mar 16, 2015 at 11:34 AM, Peter Blodow
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] VFD causing limits to trip. Huh?
On Mon, Mar 16, 2015 at 11:34 AM, Peter Blodow
p.blo...@dreki.de wrote:
Steve,
this is a good description of noise reduction by shielding.
To make it
more exact, the shield should
On Mon, Mar 16, 2015 at 11:34 AM, Peter Blodow p.blo...@dreki.de wrote:
Steve,
this is a good description of noise reduction by shielding. To make it
more exact, the shield should be grounded at the end where the lower
impedance is, mostly the signal source.
This is opposite to what Steve
On Mon, Mar 16, 2015 at 4:40 PM, Karlsson Wang
nicklas.karls...@karlssonwang.se wrote:
I think you are right and will just try to dig a little bit deeper.
A shield is primarily intended to prevent electrostatic coupling from the
outside world. So by grounding in the consuming end the shield
On Tue, Mar 17, 2015 at 5:49 AM, Nicklas Karlsson
nicklas.karls...@karlssonwang.se wrote:
Yes a shield has two primary jobs but ground impedance is far from zero at
high frequency. The shield will not stay at fixed potential at high
frequency for a noise source.
If there are three-phase
Yes a shield has two primary jobs but ground impedance is far from zero at
high frequency. The shield will not stay at fixed potential at high
frequency for a noise source.
If there are three-phase input and a ground Cable summed current thru all
four may be zero but there may be a current flow
On 03/17/2015 12:33 AM, Karlsson Wang wrote:
The frequency converters I have seen for electric motors generate a
square wave voltage. To generate a sinus the duty cycle is varied to
get sinus voltage in average and usually the current is close to
sinus.
Most modern converters are class D
On 03/16/2015 09:40 PM, Karlsson Wang wrote:
A shield is primarily intended to prevent electrostatic coupling from
the outside world. So by grounding in the consuming end the shield
will get the ground potential of the consumer and the signal cables
will be shielded from different external
...@gmail.com]
Sent: Monday, March 16, 2015 7:54 AM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] VFD causing limits to trip. Huh?
Are the shielded wires only grounded at one end and at the
controller end?
On Sun, Mar 15, 2015 at 1:22 PM, Karlsson Wang
nicklas.karls
Are the shielded wires only grounded at one end and at the controller end?
On Sun, Mar 15, 2015 at 1:22 PM, Karlsson Wang
nicklas.karls...@karlssonwang.se wrote:
I think grounding is the most important. There are normally a common mode
voltage at the inverter output to motor so the inverter
-Original Message-
From: Matt Tucci [mailto:matt2c1...@gmail.com]
Sent: Monday, March 16, 2015 7:54 AM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] VFD causing limits to trip. Huh?
Are the shielded wires only grounded at one end and at the
controller end?
On Sun, Mar 15
The frequency converters I have seen for electric motors generate a square wave
voltage. To generate a sinus the duty cycle is varied to get sinus voltage in
average and usually the current is close to sinus.
Then it come to quality I guess the large difference is in filters and coupling
to
: [Emc-users] VFD causing limits to trip. Huh?
Are the shielded wires only grounded at one end and at the
controller end?
On Sun, Mar 15, 2015 at 1:22 PM, Karlsson Wang
nicklas.karls...@karlssonwang.se wrote:
I think grounding is the most important. There are normally
Pardon my ignorance...
But is there a significant difference between use of shielded cable between VFD
and motor vrs lines in hard or flex metal conduit which makes a complete ground
at each end?
Thanks
Greg
--
Dive
On 03/16/2015 07:33 PM, Greg Bentzinger wrote:
Pardon my ignorance...
But is there a significant difference between use of shielded cable
between VFD and motor vrs lines in hard or flex metal conduit which
makes a complete ground at each end?
Both cable-shield and a conducting cable-pipe
On Sun, 15 Mar 2015, Kirk Wallace wrote:
Date: Sun, 15 Mar 2015 07:54:46 -0700
From: Kirk Wallace kwall...@wallacecompany.com
Reply-To: Enhanced Machine Controller (EMC)
emc-users@lists.sourceforge.net
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] VFD causing limits
I promised to report back so...
I fitted the filter (Schaffner FN2030 Series 16A 250 V ac 400Hz) on the
VFD mains input and that did make a difference. My failing case job ran
70% of the way through where without it the job failed 10% in. Not the
complete solution though.
I then tried a
On 03/15/2015 07:39 AM, Russell Brown wrote:
I promised to report back so...
I fitted the filter (Schaffner FN2030 Series 16A 250 V ac 400Hz) on the
VFD mains input and that did make a difference. My failing case job ran
70% of the way through where without it the job failed 10% in. Not
I think grounding is the most important. There are normally a common mode
voltage at the inverter output to motor so the inverter power ground will
bounce around each time inverter is switched. If this bouncing is coupled to
the logic ground there may be a lot of problems.
Nicklas Karlsson
Here
http://www.beama.org.uk/en/publications/technical-guides.cfm/motor-shaft-voltages
is a another pain in the regions not to far behind called bearing currents.
Regards Nicklas Karlsson
On Fri, 06 Mar 2015 12:34:07 -0500
Dave Cole linuxcncro...@gmail.com wrote:
VFDs and AC servo drives
Grounding is really important. Noise on logical ground usually cause
communication errors and could of course trigger a limit swith, have you tried
lower input impedance?
A common mode filter on the output may be a good idea.
I have the theoretical knowledge but limited experience.
Nicklas
) emc-users@lists.sourceforge.net
Sent: Friday, March 6, 2015 1:58:09 PM
Subject: Re: [Emc-users] VFD causing limits to trip. Huh?
My 2'X4' CNC router has a 2.2 KW water cooled spindle and VFD - the
typical Chinese kit off eBay.
http://www.ebay.com/itm/221354796303
I'm getting noise
On 03/07/2015 12:44 AM, Russell Brown wrote:
Many thanks for all the input chaps.
The consensus seems to be
a) Add a mains input filter.
b) Shield the limit switch wires.
c) Stick ferrites in.
d) Mask the problem with a debounce :-)
Another method to consider. Common inputs have high
Many thanks for all the input chaps.
The consensus seems to be
a) Add a mains input filter.
b) Shield the limit switch wires.
c) Stick ferrites in.
d) Mask the problem with a debounce :-)
As I have a pretty solid failing case, I figure it's worth while seeing
if A-C can fix it before masking
On 3/6/2015 6:54 AM, Todd Zuercher wrote:
You might be able to get away with just adding a debounce to the limit
inputs. That worked for me on a machine that was giving me false trips on
the X limit. I suspected mine was a dodgy cable at the time, but it might
have been cross talk since it
On 3/6/2015 1:52 PM, Bruce Layne wrote:
The LCD is on an articulated arm, a little above eye level, mounted to
the side of the large nonmetallic enclosure. The VFD is mounted in the
steel electrical enclosure about five feet lower. The cables all exit
through cable clamps in holes on the
On 03/06/2015 07:19 PM, Gregg Eshelman wrote:
On 3/6/2015 6:54 AM, Todd Zuercher wrote:
You might be able to get away with just adding a debounce to the limit
inputs. That worked for me on a machine that was giving me false trips on
the X limit. I suspected mine was a dodgy cable at the
Zuercher,
If Gene is right, then there is a really big loop area. Ether the leads to the
motor / drive are taking different paths or the is a big ground loop some place.
You could try moving the leads around to confirm what Gene is suggesting. If
this is the case, check for ground loops. If
Hi Russel,
I got exactly the same troubles describes with the VFDs creating a lot
of perturbation. Aspiration was also making perturbation for me.
Thankfully at my work place we have experts on EMI and Stephen advices
are what you need to follow.
In my case, to solve it I had to shield the cable
Wiring to the switch is damaged somewhere?
On Fri, Mar 6, 2015 at 6:56 AM, Russell Brown russ...@lls.lls.com wrote:
I've just fitted one of them there 'Chinese' 2.2kW watercooled motors
with a Huanyang VFD as a second spindle on my mill.
Last night doing some pocketing, when the cutter got
EMI. VFDs generate lots of it. You're likely getting lots of noise coupled
into your limit switch cabling. Shield the vfd wires if possible. Running in a
shielded single cable is probably best. Separate the motor and switch cables as
much as possible too.
On March 6, 2015 6:56:08 AM EST,
You could also put a reactor between the motor and drive. Might be a good idea
to put a line filter on the power leads to the drive too.
I'm not a fan of shielding, but it's certainly an option as well.
N. Christopher Perry
On Mar 6, 2015, at 7:36 AM, Stephen Dubovsky smdubov...@gmail.com
the debounce.
- Original Message -
From: N. Christopher Perry vwpe...@comcast.net
To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net
Sent: Friday, March 6, 2015 8:10:55 AM
Subject: Re: [Emc-users] VFD causing limits to trip. Huh?
You could also put a reactor between the motor
VFDs and AC servo drives oftentimes create noise on the incoming AC
power lines to the drives.That noise can cause interference issues
with system electronics.
I recommend you purchase an incoming line filter to keep the noise from
backing up into your AC power line.
This is a filter I
On 6 Mar 2015, at 12:56, Russell Brown russ...@lls.lls.com wrote:
Any ideas what might cause this?
Almost certainly EMI. An input filter for the VFD can help. Check eBay for
Rasmi they are not expensive.
If your mill is not downstream of an RCD then I have one spare you can have.
My 2'X4' CNC router has a 2.2 KW water cooled spindle and VFD - the
typical Chinese kit off eBay.
http://www.ebay.com/itm/221354796303
I'm getting noise on the video signal that usually causes annoying
screen jitter but sometimes blanks out the screen entirely, which can be
a bit
...@thinkingdevices.com
To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net
Sent: Friday, March 6, 2015 1:58:09 PM
Subject: Re: [Emc-users] VFD causing limits to trip. Huh?
My 2'X4' CNC router has a 2.2 KW water cooled spindle and VFD - the
typical Chinese kit off eBay.
http
That's the big brother of the one I picked.
N. Christopher Perry
On Mar 6, 2015, at 12:34 PM, Dave Cole linuxcncro...@gmail.com wrote:
VFDs and AC servo drives oftentimes create noise on the incoming AC
power lines to the drives.That noise can cause interference issues
with system
On 3/6/2015 1:43 PM, Todd Zuercher wrote:
What sort of screen? and where is it in relation to the VFD? We have
a router with 2 VFDs mounted on the outside of a wooden cabinet, and
they wreak havoc on the CRT display inside the cabinet when they
accelerate/decelerate (about 6 inches away). It
On 03/06/2015 02:43 PM, Todd Zuercher wrote:
What sort of screen?
20 LCD. Dell, I think.
Where is it in relation to the VFD?
The LCD is on an articulated arm, a little above eye level, mounted to
the side of the large nonmetallic enclosure. The VFD is mounted in the
steel electrical
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