Re: [Emc-users] Checking vfd hookup question?

[andrew beck]

Hey everyone.

Thanks for all the ideas.

Just a couple of thoughts.

I'm in New Zealand so need a nz source of parts or it gets to expensive for
shipping.

And my drive is a 400v drive I think dc bus voltage gets up to about 650vdc.

Sounds like I need to do some resistance calculations..

Regards

Andrew

On Sun, Dec 27, 2020, 9:20 AM Gene Heskett  wrote:

> On Saturday 26 December 2020 12:35:17 Dave Cole wrote:
>
> > I'm sure those could be made to work if they are of an acceptable Ohms
> > range, but how do you mount them?
> > They are just elements.
> > Most braking resistors on larger machines are in cages on the top or
> > side of the control panels.
> > For small drives, they are oftentimes just screwed to the panel
> > backplane,   But then they don't get that hot.
> >
> > By the time you fab the cage, you can almost buy one new with a cage
> > and that is rated.
>
> Which is what I did, but its not in a cage, its encapsulated in a 1x2 alu
> extrusion about 8" long with bolt holes in the end tabs. $29.95 + ship
> from a seller in KY. With leads long enough I can hang it on the
> plumbers strapping holding up the shelf the electrics are on above the
> 6040.
>
> > Dave
> >
> > On 12/24/2020 1:36 PM, Jon Elson wrote:
> > > On 12/24/2020 11:43 AM, Dave Cole wrote:
> > >> Automation Direct sells braking resistors.
> > >> https://www.automationdirect.com/adc/shopping/catalog/drives_-a-_so
> > >>ft_starters/ac_variable_frequency_drives_(vfd)/vfd_accessories/braki
> > >>ng_units_-a-_resistors
> > >>
> > >> Looks like the cheapest one is about $30.
> > >
> > > I've used stovetop elements from eBay for about $12 or so.  If they
> > > are good enough for
> > > Haas in mass manufacture, they ought to be good enough for me.
> > >
> > > 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
>
>
> 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)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
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Re: [Emc-users] Checking vfd hookup question?

[Gene Heskett]

On Saturday 26 December 2020 12:35:17 Dave Cole wrote:

> I'm sure those could be made to work if they are of an acceptable Ohms
> range, but how do you mount them?
> They are just elements.
> Most braking resistors on larger machines are in cages on the top or
> side of the control panels.
> For small drives, they are oftentimes just screwed to the panel
> backplane,   But then they don't get that hot.
>
> By the time you fab the cage, you can almost buy one new with a cage
> and that is rated.

Which is what I did, but its not in a cage, its encapsulated in a 1x2 alu 
extrusion about 8" long with bolt holes in the end tabs. $29.95 + ship 
from a seller in KY. With leads long enough I can hang it on the 
plumbers strapping holding up the shelf the electrics are on above the 
6040.

> Dave
>
> On 12/24/2020 1:36 PM, Jon Elson wrote:
> > On 12/24/2020 11:43 AM, Dave Cole wrote:
> >> Automation Direct sells braking resistors.
> >> https://www.automationdirect.com/adc/shopping/catalog/drives_-a-_so
> >>ft_starters/ac_variable_frequency_drives_(vfd)/vfd_accessories/braki
> >>ng_units_-a-_resistors
> >>
> >> Looks like the cheapest one is about $30.
> >
> > I've used stovetop elements from eBay for about $12 or so.  If they
> > are good enough for
> > Haas in mass manufacture, they ought to be good enough for me.
> >
> > 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


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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] Checking vfd hookup question?

[Dave Cole]

I'm sure those could be made to work if they are of an acceptable Ohms 
range, but how do you mount them?

They are just elements.
Most braking resistors on larger machines are in cages on the top or 
side of the control panels.
For small drives, they are oftentimes just screwed to the panel 
backplane,   But then they don't get that hot.


By the time you fab the cage, you can almost buy one new with a cage and 
that is rated.


Dave

On 12/24/2020 1:36 PM, Jon Elson wrote:

On 12/24/2020 11:43 AM, Dave Cole wrote:

Automation Direct sells braking resistors.
https://www.automationdirect.com/adc/shopping/catalog/drives_-a-_soft_starters/ac_variable_frequency_drives_(vfd)/vfd_accessories/braking_units_-a-_resistors 


Looks like the cheapest one is about $30.
I've used stovetop elements from eBay for about $12 or so.  If they 
are good enough for

Haas in mass manufacture, they ought to be good enough for me.

Jon


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Re: [Emc-users] Checking vfd hookup question?

[Jon Elson]

On 12/24/2020 11:43 AM, Dave Cole wrote:

Automation Direct sells braking resistors.
https://www.automationdirect.com/adc/shopping/catalog/drives_-a-_soft_starters/ac_variable_frequency_drives_(vfd)/vfd_accessories/braking_units_-a-_resistors 


Looks like the cheapest one is about $30.
I've used stovetop elements from eBay for about $12 or so.  
If they are good enough for

Haas in mass manufacture, they ought to be good enough for me.

Jon


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Re: [Emc-users] Checking vfd hookup question?

[Dave Cole]

Automation Direct sells braking resistors.
https://www.automationdirect.com/adc/shopping/catalog/drives_-a-_soft_starters/ac_variable_frequency_drives_(vfd)/vfd_accessories/braking_units_-a-_resistors
Looks like the cheapest one is about $30.
But unless you are hitting the brakes constantly, they usually don't get 
hot.
A 300 watt (continuously rated) would be good for a 2+ kw drive if you 
aren't using it constantly.
The problem with using a stove element is that you will need to protect 
the terminals.   A 240 input drive has about a 350v DC bus voltage.

You don't want to get shocked with 350 VDC!

Dave

On 12/24/2020 11:06 AM, Jon Elson wrote:

On 12/24/2020 02:18 AM, Chris Albertson wrote:
"All the time?"    When you have a hard requirement like this is when 
some
detailed engineering can pay off.    Assume you are reversing at 50% 
duty

cycle and burning 1KW 50% of the time.   Where I live this can cost 12
cents per hour.  This is $89 per month if you actually do run "all the
time".  Or $1,000 per year.  Or maybe you are usig a lower value 
resister

and burning 4KW with your brake?   That is $4K per year
The VFD only turns the braking resistor on when the DC link voltage 
rises above some limit due to energy returned from the motor during 
deceleration.  I never detect any warming on mine except during rigid 
tapping cycles.
A better way is to use a battery inside the power supply.   a 100 
amp-hour

lithium battery would cost possibly $400.

You are going to need a 340 V battery bank, and a charger for it.

Jon


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Re: [Emc-users] Checking vfd hookup question?

[Jon Elson]

On 12/24/2020 02:18 AM, Chris Albertson wrote:

"All the time?"When you have a hard requirement like this is when some
detailed engineering can pay off.Assume you are reversing at 50% duty
cycle and burning 1KW 50% of the time.   Where I live this can cost 12
cents per hour.  This is $89 per month if you actually do run "all the
time".  Or $1,000 per year.  Or maybe you are usig a lower value resister
and burning 4KW with your brake?   That is $4K per year
The VFD only turns the braking resistor on when the DC link 
voltage rises above some limit due to energy returned from 
the motor during deceleration.  I never detect any warming 
on mine except during rigid tapping cycles.

A better way is to use a battery inside the power supply.   a 100 amp-hour
lithium battery would cost possibly $400.
You are going to need a 340 V battery bank, and a charger 
for it.


Jon


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Re: [Emc-users] Checking vfd hookup question?

[Gene Heskett]

On Thursday 24 December 2020 03:18:24 Chris Albertson wrote:

> "All the time?"When you have a hard requirement like this is when
> some detailed engineering can pay off.Assume you are reversing at
> 50% duty cycle and burning 1KW 50% of the time.   Where I live this
> can cost 12 cents per hour.  This is $89 per month if you actually do
> run "all the time".  Or $1,000 per year.  Or maybe you are usig a
> lower value resister and burning 4KW with your brake?   That is $4K
> per year
>
> A better way is to use a battery inside the power supply.   a 100
> amp-hour lithium battery would cost possibly $400.  Then the braking
> energy goes into the battery and then a few seconds later the battery
> is used to run the spindle in the forward direction.   The battery
> needs to be sized so that the energy transferred each cycle is small
> (maybe 1%) of the total capacity.The power supply only has to
> supply power to
> overcome friction.   Most of the energy to accelerate the load comes
> from the brake.
>
> This is exactly how a hybrid car works.   They are most efficient with
> batteries that work at about 400 volts or more.
>
> THis said, I doubt anyone is actually going to run a 7.5KW motor at
> max performance forward reverse cycles for hours on end.   But if you
> do running a stove element is not cheap.
>
> It is really not very complex to brake with a battery as long as the
> battery is very large relative to the current.  A double H-bridge is
> all you need.
>
>
You make a very good argument. Using my GO704 with a stock PMDC motor as 
an example, but running on around 127 volts instead of the nameplate 90 
volts, administered by one of Jon's pwm-servo amps, with the reverse 
sequence controlled by some limit3 in the hal file, I block the reversal 
and program a quick stop by zeroing the input to a limit3, which dumps 
the motor back into the psu, running it up to about 170 volts as it does 
so. But the stop is sensed by a oneshot watching an encoder signal, and 
when 10 millisecs has passed, with no encoder, it finally allows the 
reverse to get to the controller, the requested speed input to the 
limit3 is restored, and that ramps it back up to the S speed set, using 
up that excess charge in the psu. only when the charge in their 
considerable number of microfarads is used up does it resume drawing 
power from the powerline. And the reversal time, even at 3000 rpm is 
less than 400 milliseconds. That peak at 170 volts is well above the 
voltage rating of those caps, but it is such a short duration that the 
average heating from their leakage has not damaged them in close to 5 
years.  And at tapping speeds of say 500 rpm in low gear, the overtravel 
at the bottom of a G33.1 is well under a full turn. Jons pwm-servo is 
set to limit the currant at 17 amps, not quite double the nameplate 9.7 
amps, and the current limit makes the iron in the motor chirp for a 
small fraction of a second. NO other excitement. When I am tapping a 
hole big enough I have to peck the tap, I have a 4 second wait at the 
top of the routine, long enough to clean the tap with an air hose and 
give it another drop of cutting oil. I have tapped 7/16xUSS holes in 
1/2" alu that way.

Pretty good for a cheap machine with plastic gears that is permanently 
out of tram because the post isn't vertical. The bolt holes are far 
enough off I can't fix it without reaming the holes thru the post to the 
next mm up. A reamer I didn't have the last time I had it apart. But 
that is a different story. The point is, that I am recovering that 
energy from the motor, and using it to restore its speed in the other 
direction, and its equally as effective at the opposite M4 to M3 
reversal at the top of the stroke.

I am using a similar bit of hal trickery in the rpi4 config on the 
Sheldon with a resistorless vfd. I rigid tap there at 100 rpms, and with 
a nearly 40 lb 8" chuck mounted, the over travel there is .24 turns. 
Much worse at higher speeds of coarse. Its a permanent part of my axis 
display.

> On Wed, Dec 23, 2020 at 9:23 PM Scott Harwell via Emc-users <
>
> emc-users@lists.sourceforge.net> wrote:
> >  THE Huan Yang 7.5 requires 1000 watt at 75 ohms.
> >
> >
> >
> >
> > On Wednesday, December 23, 2020, 8:17:03 PM CST, andrew beck <
> > andrewbeck0...@gmail.com> wrote:
> >
> >  Just to tag in.
> >
> > I need a braking resistor for my cnc mill spindle it's a 7.5kw vfd.
> >
> > Needs to rigid tap all the time etc


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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] Checking vfd hookup question?

[Chris Albertson]

"All the time?"When you have a hard requirement like this is when some
detailed engineering can pay off.Assume you are reversing at 50% duty
cycle and burning 1KW 50% of the time.   Where I live this can cost 12
cents per hour.  This is $89 per month if you actually do run "all the
time".  Or $1,000 per year.  Or maybe you are usig a lower value resister
and burning 4KW with your brake?   That is $4K per year

A better way is to use a battery inside the power supply.   a 100 amp-hour
lithium battery would cost possibly $400.  Then the braking energy goes
into the battery and then a few seconds later the battery is used to run
the spindle in the forward direction.   The battery needs to be sized so
that the energy transferred each cycle is small (maybe 1%) of the total
capacity.The power supply only has to supply power to
overcome friction.   Most of the energy to accelerate the load comes from
the brake.

This is exactly how a hybrid car works.   They are most efficient with
batteries that work at about 400 volts or more.

THis said, I doubt anyone is actually going to run a 7.5KW motor at max
performance forward reverse cycles for hours on end.   But if you do
running a stove element is not cheap.

It is really not very complex to brake with a battery as long as the
battery is very large relative to the current.  A double H-bridge is all
you need.



On Wed, Dec 23, 2020 at 9:23 PM Scott Harwell via Emc-users <
emc-users@lists.sourceforge.net> wrote:

>  THE Huan Yang 7.5 requires 1000 watt at 75 ohms.
>
>
>
>
> On Wednesday, December 23, 2020, 8:17:03 PM CST, andrew beck <
> andrewbeck0...@gmail.com> wrote:
>
>  Just to tag in.
>
> I need a braking resistor for my cnc mill spindle it's a 7.5kw vfd.
>
> Needs to rigid tap all the time etc
>
-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] Checking vfd hookup question?

[Scott Harwell via Emc-users]

 THE Huan Yang 7.5 requires 1000 watt at 75 ohms. 




On Wednesday, December 23, 2020, 8:17:03 PM CST, andrew beck 
 wrote:  
 
 Just to tag in.

I need a braking resistor for my cnc mill spindle it's a 7.5kw vfd.

Needs to rigid tap all the time etc

Any ideas?  I like the idea of a stove element..

Just need to know some values etc

On Thu, Dec 24, 2020, 7:52 AM Chris Albertson 
wrote:

> Yes, as I wrote above, the resister specs depend a lot on how often you
> intend to reverse the direction of the spindle.    And how quickly.
>
> A resister of "infinite" resistance (open circuit. eg "no resister at all")
> can work but will give lower performance braking power.  This would be
> "good enough" for many cases but maybe the intended usage is to do rigid
> tapping on thousands of holes at the highest possible rate in a production
> environment.
>
> I think in this case, just compromise.  A resister at the higher end of the
> resistance range would not need so many Watts rating.  "i^^2*r"  will tell
> you.
>
>
> On Wed, Dec 23, 2020 at 5:50 AM Todd Zuercher 
> wrote:
>
> > I doubt you'd really need a braking resistor for running a router spindle
> > (what I believe you have.)  Simply test it without one, as long as you
> > don't get overvoltage alarms on the VFD when decelerating you should good
> > without it (assuming your VFD has adequate safety alarms which might be a
> > big assumption with a Chinese piece.)
> > I've not run into a machine that uses one myself, but I only work with
> > large commercial router machines. (not any mills or lathes) and router
> > spindles don't have the rotating inertia that other machines like a lathe
> > might or the need to stop super fast.
> >
> > Todd Zuercher
> > P. Graham Dunn Inc.
> > 630 Henry Street
> > Dalton, Ohio 44618
> > Phone:  (330)828-2105ext. 2031
> >
> > -Original Message-
> > From: Jon Elson 
> > Sent: Tuesday, December 22, 2020 8:51 PM
> > To: Enhanced Machine Controller (EMC) 
> > Subject: Re: [Emc-users] Checking vfd hookup question?
> >
> > [EXTERNAL EMAIL] Be sure links are safe.
> >
> > On 12/22/2020 06:30 PM, Matthew Herd wrote:
> > > In my research on resistor sizing, I heard reports that Haas uses stove
> > elements for their braking resistors.  On factory machines, no less.  Of
> > course that’s second hand, so I can’t say it’s true.
> > >
> > >
> > Yes, absolutely.  Our Haas at work has a stovetop element in a screen
> > guard on the back of the machine.
> > All of them are made like that.  It is a perfect solution for a 240 V
> > machine.  But, for the smaller VFDs you want a small stovetop element so
> it
> > doesn't draw excessive current.  Assuming a voltage doubler on a
> > 120 V VFD, it will still have 340V or so DC on the DC link, same as a 240
> > V VFD.  A 40 Ohm element should draw less than
> > 10 A, which should be safe for anything but the smallest VFD.  So, get
> the
> > 7" stovetop elements, not the 11" ones.
> >
> > Using too low a resistance won't harm the MOTOR, it will blow the power
> > brick in the VFD.
> >
> > 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
> >
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
>
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Re: [Emc-users] Checking vfd hookup question?

[Scott Harwell via Emc-users]

 Amazon   660533 8 inch large surface element 2600 watt $15.89 us.
It should be popular during the winter.





On Wednesday, December 23, 2020, 8:17:03 PM CST, andrew beck 
 wrote:  
 
 Just to tag in.

I need a braking resistor for my cnc mill spindle it's a 7.5kw vfd.

Needs to rigid tap all the time etc

Any ideas?  I like the idea of a stove element..

Just need to know some values etc

On Thu, Dec 24, 2020, 7:52 AM Chris Albertson 
wrote:

> Yes, as I wrote above, the resister specs depend a lot on how often you
> intend to reverse the direction of the spindle.    And how quickly.
>
> A resister of "infinite" resistance (open circuit. eg "no resister at all")
> can work but will give lower performance braking power.  This would be
> "good enough" for many cases but maybe the intended usage is to do rigid
> tapping on thousands of holes at the highest possible rate in a production
> environment.
>
> I think in this case, just compromise.  A resister at the higher end of the
> resistance range would not need so many Watts rating.  "i^^2*r"  will tell
> you.
>
>
> On Wed, Dec 23, 2020 at 5:50 AM Todd Zuercher 
> wrote:
>
> > I doubt you'd really need a braking resistor for running a router spindle
> > (what I believe you have.)  Simply test it without one, as long as you
> > don't get overvoltage alarms on the VFD when decelerating you should good
> > without it (assuming your VFD has adequate safety alarms which might be a
> > big assumption with a Chinese piece.)
> > I've not run into a machine that uses one myself, but I only work with
> > large commercial router machines. (not any mills or lathes) and router
> > spindles don't have the rotating inertia that other machines like a lathe
> > might or the need to stop super fast.
> >
> > Todd Zuercher
> > P. Graham Dunn Inc.
> > 630 Henry Street
> > Dalton, Ohio 44618
> > Phone:  (330)828-2105ext. 2031
> >
> > -Original Message-
> > From: Jon Elson 
> > Sent: Tuesday, December 22, 2020 8:51 PM
> > To: Enhanced Machine Controller (EMC) 
> > Subject: Re: [Emc-users] Checking vfd hookup question?
> >
> > [EXTERNAL EMAIL] Be sure links are safe.
> >
> > On 12/22/2020 06:30 PM, Matthew Herd wrote:
> > > In my research on resistor sizing, I heard reports that Haas uses stove
> > elements for their braking resistors.  On factory machines, no less.  Of
> > course that’s second hand, so I can’t say it’s true.
> > >
> > >
> > Yes, absolutely.  Our Haas at work has a stovetop element in a screen
> > guard on the back of the machine.
> > All of them are made like that.  It is a perfect solution for a 240 V
> > machine.  But, for the smaller VFDs you want a small stovetop element so
> it
> > doesn't draw excessive current.  Assuming a voltage doubler on a
> > 120 V VFD, it will still have 340V or so DC on the DC link, same as a 240
> > V VFD.  A 40 Ohm element should draw less than
> > 10 A, which should be safe for anything but the smallest VFD.  So, get
> the
> > 7" stovetop elements, not the 11" ones.
> >
> > Using too low a resistance won't harm the MOTOR, it will blow the power
> > brick in the VFD.
> >
> > 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
> >
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
>
> ___
> Emc-users mailing list
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>

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Re: [Emc-users] Checking vfd hookup question?

[Jon Elson]

On 12/23/2020 06:55 PM, andrew beck wrote:

Just to tag in.

I need a braking resistor for my cnc mill spindle it's a 7.5kw vfd.

Needs to rigid tap all the time etc

Any ideas?  I like the idea of a stove element..

Just need to know some values etc


Get the 11" stove elements.  A 2400 W element will draw 10 A 
at 240 V, therefore the resistance is
about 23 Ohms.  At 340 V DC, the element will draw 14.8 A.  
That is probably a safe number, but don't go above that 
(higher wattage or lower resistance).  Probably a 1700 W 
element will work fine, but may not provide quite as much 
braking.  I'm using two 50 W resistors on my lathe with 5 Hp 
motor, and it provides excellent braking, bringing the 
spindle to a stop in under one second.  But, I am not set up 
for rigid tapping, so I don't know how hot it would get 
under repeated reversals.


Jon


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Re: [Emc-users] Checking vfd hookup question?

[Gene Heskett]

On Wednesday 23 December 2020 19:55:48 andrew beck wrote:

> Just to tag in.
>
> I need a braking resistor for my cnc mill spindle it's a 7.5kw vfd.
>
Need pwr src voltage etc, and I'll look it up in the Huanyang book.

> Needs to rigid tap all the time etc
>
> Any ideas?  I like the idea of a stove element..
>
> Just need to know some values etc
>
> On Thu, Dec 24, 2020, 7:52 AM Chris Albertson
> 
>
> wrote:
> > Yes, as I wrote above, the resister specs depend a lot on how often
> > you intend to reverse the direction of the spindle.And how
> > quickly.
> >
> > A resister of "infinite" resistance (open circuit. eg "no resister
> > at all") can work but will give lower performance braking power.  
> > This would be "good enough" for many cases but maybe the intended
> > usage is to do rigid tapping on thousands of holes at the highest
> > possible rate in a production environment.
> >
> > I think in this case, just compromise.  A resister at the higher end
> > of the resistance range would not need so many Watts rating. 
> > "i^^2*r"  will tell you.
> >
> >
> > On Wed, Dec 23, 2020 at 5:50 AM Todd Zuercher
> > 
> >
> > wrote:
> > > I doubt you'd really need a braking resistor for running a router
> > > spindle (what I believe you have.)  Simply test it without one, as
> > > long as you don't get overvoltage alarms on the VFD when
> > > decelerating you should good without it (assuming your VFD has
> > > adequate safety alarms which might be a big assumption with a
> > > Chinese piece.)
> > > I've not run into a machine that uses one myself, but I only work
> > > with large commercial router machines. (not any mills or lathes)
> > > and router spindles don't have the rotating inertia that other
> > > machines like a lathe might or the need to stop super fast.
> > >
> > > Todd Zuercher
> > > P. Graham Dunn Inc.
> > > 630 Henry Street
> > > Dalton, Ohio 44618
> > > Phone:  (330)828-2105ext. 2031
> > >
> > > -Original Message-
> > > From: Jon Elson 
> > > Sent: Tuesday, December 22, 2020 8:51 PM
> > > To: Enhanced Machine Controller (EMC)
> > >  Subject: Re: [Emc-users]
> > > Checking vfd hookup question?
> > >
> > > [EXTERNAL EMAIL] Be sure links are safe.
> > >
> > > On 12/22/2020 06:30 PM, Matthew Herd wrote:
> > > > In my research on resistor sizing, I heard reports that Haas
> > > > uses stove
> > >
> > > elements for their braking resistors.  On factory machines, no
> > > less.  Of course that’s second hand, so I can’t say it’s true.
> > >
> > >
> > > Yes, absolutely.  Our Haas at work has a stovetop element in a
> > > screen guard on the back of the machine.
> > > All of them are made like that.  It is a perfect solution for a
> > > 240 V machine.  But, for the smaller VFDs you want a small
> > > stovetop element so
> >
> > it
> >
> > > doesn't draw excessive current.  Assuming a voltage doubler on a
> > > 120 V VFD, it will still have 340V or so DC on the DC link, same
> > > as a 240 V VFD.  A 40 Ohm element should draw less than
> > > 10 A, which should be safe for anything but the smallest VFD.  So,
> > > get
> >
> > the
> >
> > > 7" stovetop elements, not the 11" ones.
> > >
> > > Using too low a resistance won't harm the MOTOR, it will blow the
> > > power brick in the VFD.
> > >
> > > 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
> >
> > --
> >
> > Chris Albertson
> > Redondo Beach, California
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
> ___
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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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-users] Checking vfd hookup question?

[andy pugh]

On Thu, 24 Dec 2020 at 02:17, andrew beck  wrote:

> I need a braking resistor for my cnc mill spindle it's a 7.5kw vfd.

> Any ideas?  I like the idea of a stove element..

The VFD manual will suggest a resistance and power. But I would
imagine there is a fairly wide acceptable range. (especially power,
too much would never be a problem)

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] Checking vfd hookup question?

[andrew beck]

Just to tag in.

I need a braking resistor for my cnc mill spindle it's a 7.5kw vfd.

Needs to rigid tap all the time etc

Any ideas?  I like the idea of a stove element..

Just need to know some values etc

On Thu, Dec 24, 2020, 7:52 AM Chris Albertson 
wrote:

> Yes, as I wrote above, the resister specs depend a lot on how often you
> intend to reverse the direction of the spindle.And how quickly.
>
> A resister of "infinite" resistance (open circuit. eg "no resister at all")
> can work but will give lower performance braking power.   This would be
> "good enough" for many cases but maybe the intended usage is to do rigid
> tapping on thousands of holes at the highest possible rate in a production
> environment.
>
> I think in this case, just compromise.  A resister at the higher end of the
> resistance range would not need so many Watts rating.  "i^^2*r"  will tell
> you.
>
>
> On Wed, Dec 23, 2020 at 5:50 AM Todd Zuercher 
> wrote:
>
> > I doubt you'd really need a braking resistor for running a router spindle
> > (what I believe you have.)  Simply test it without one, as long as you
> > don't get overvoltage alarms on the VFD when decelerating you should good
> > without it (assuming your VFD has adequate safety alarms which might be a
> > big assumption with a Chinese piece.)
> > I've not run into a machine that uses one myself, but I only work with
> > large commercial router machines. (not any mills or lathes) and router
> > spindles don't have the rotating inertia that other machines like a lathe
> > might or the need to stop super fast.
> >
> > Todd Zuercher
> > P. Graham Dunn Inc.
> > 630 Henry Street
> > Dalton, Ohio 44618
> > Phone:  (330)828-2105ext. 2031
> >
> > -Original Message-
> > From: Jon Elson 
> > Sent: Tuesday, December 22, 2020 8:51 PM
> > To: Enhanced Machine Controller (EMC) 
> > Subject: Re: [Emc-users] Checking vfd hookup question?
> >
> > [EXTERNAL EMAIL] Be sure links are safe.
> >
> > On 12/22/2020 06:30 PM, Matthew Herd wrote:
> > > In my research on resistor sizing, I heard reports that Haas uses stove
> > elements for their braking resistors.  On factory machines, no less.  Of
> > course that’s second hand, so I can’t say it’s true.
> > >
> > >
> > Yes, absolutely.  Our Haas at work has a stovetop element in a screen
> > guard on the back of the machine.
> > All of them are made like that.  It is a perfect solution for a 240 V
> > machine.  But, for the smaller VFDs you want a small stovetop element so
> it
> > doesn't draw excessive current.  Assuming a voltage doubler on a
> > 120 V VFD, it will still have 340V or so DC on the DC link, same as a 240
> > V VFD.  A 40 Ohm element should draw less than
> > 10 A, which should be safe for anything but the smallest VFD.  So, get
> the
> > 7" stovetop elements, not the 11" ones.
> >
> > Using too low a resistance won't harm the MOTOR, it will blow the power
> > brick in the VFD.
> >
> > 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
> >
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
>
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Re: [Emc-users] Checking vfd hookup question?

[Chris Albertson]

Yes, as I wrote above, the resister specs depend a lot on how often you
intend to reverse the direction of the spindle.And how quickly.

A resister of "infinite" resistance (open circuit. eg "no resister at all")
can work but will give lower performance braking power.   This would be
"good enough" for many cases but maybe the intended usage is to do rigid
tapping on thousands of holes at the highest possible rate in a production
environment.

I think in this case, just compromise.  A resister at the higher end of the
resistance range would not need so many Watts rating.  "i^^2*r"  will tell
you.


On Wed, Dec 23, 2020 at 5:50 AM Todd Zuercher  wrote:

> I doubt you'd really need a braking resistor for running a router spindle
> (what I believe you have.)  Simply test it without one, as long as you
> don't get overvoltage alarms on the VFD when decelerating you should good
> without it (assuming your VFD has adequate safety alarms which might be a
> big assumption with a Chinese piece.)
> I've not run into a machine that uses one myself, but I only work with
> large commercial router machines. (not any mills or lathes) and router
> spindles don't have the rotating inertia that other machines like a lathe
> might or the need to stop super fast.
>
> Todd Zuercher
> P. Graham Dunn Inc.
> 630 Henry Street
> Dalton, Ohio 44618
> Phone:  (330)828-2105ext. 2031
>
> -Original Message-
> From: Jon Elson 
> Sent: Tuesday, December 22, 2020 8:51 PM
> To: Enhanced Machine Controller (EMC) 
> Subject: Re: [Emc-users] Checking vfd hookup question?
>
> [EXTERNAL EMAIL] Be sure links are safe.
>
> On 12/22/2020 06:30 PM, Matthew Herd wrote:
> > In my research on resistor sizing, I heard reports that Haas uses stove
> elements for their braking resistors.  On factory machines, no less.  Of
> course that’s second hand, so I can’t say it’s true.
> >
> >
> Yes, absolutely.  Our Haas at work has a stovetop element in a screen
> guard on the back of the machine.
> All of them are made like that.  It is a perfect solution for a 240 V
> machine.  But, for the smaller VFDs you want a small stovetop element so it
> doesn't draw excessive current.  Assuming a voltage doubler on a
> 120 V VFD, it will still have 340V or so DC on the DC link, same as a 240
> V VFD.  A 40 Ohm element should draw less than
> 10 A, which should be safe for anything but the smallest VFD.  So, get the
> 7" stovetop elements, not the 11" ones.
>
> Using too low a resistance won't harm the MOTOR, it will blow the power
> brick in the VFD.
>
> Jon
>
>
> ___
> Emc-users mailing list
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>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] Checking vfd hookup question?

[Dave Cole]

On 12/22/2020 8:50 PM, Jon Elson wrote:


Using too low a resistance won't harm the MOTOR, it will blow the 
power brick in the VFD. 



Right.  The newer drives chop current off the DC bus to the braking 
resistor to lower the DC bus voltage as the motor slows.


I'd find out what they recommend.    You can oftentimes buy braking 
resistors on Ebay.  I sold some bigger ones a while back that looked 
like room heaters.


But bigger wirewound resistors should work as well.   You might not need 
one at all unless you want to slow the motor quickly. Usually if you 
slow the motor too fast and the DC bus goes into overvoltage, the drive 
just shuts down and the motor coasts. Nothing bad occurs.    So you can 
try it without a braking resistor and if you start tripping the drive 
with DC bus overvoltage alarms, then install a braking resistor.


Dave



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Re: [Emc-users] Checking vfd hookup question?

[Gene Heskett]

On Wednesday 23 December 2020 08:33:16 Todd Zuercher wrote:

> I doubt you'd really need a braking resistor for running a router
> spindle (what I believe you have.)  Simply test it without one, as
> long as you don't get overvoltage alarms on the VFD when decelerating
> you should good without it (assuming your VFD has adequate safety
> alarms which might be a big assumption with a Chinese piece.) I've not
> run into a machine that uses one myself, but I only work with large
> commercial router machines. (not any mills or lathes) and router
> spindles don't have the rotating inertia that other machines like a
> lathe might or the need to stop super fast.
>
Consider this Todd, 2 smaller 1.5 kw vfd clones, also by HY, have no 
braking R at all, yet its overshoot at reversal is under .25 turns at 
100 rpm while reversing a 40 lb chuck on the Sheldon. And I've set the 
min_speed of the motor I'm taking off at 4k revs and can sit there, 
m3-m4 and back and its just a few millisecs to the requested speed in 
the new direction. No complaints from that 110 volt vfd although an 
overhead led light does blink a little. Both of those vfd's are set to 
not exceed the motors nameplate FLA. But now I've run a separate 250 
volt line to this vfd so I doubt the led strip over the bed will blink.

There is a table in this vfd's booklet I just found that says 70 ohms at 
300 watts s/b used. I'll have to procure that however,  Generally, I've 
found that if the vfd offers DC braking, its adequate.  And I believe it 
does. We'll see but this one won't be doing any rigid tapping either so 
it shouldn't matter that much.

Thanks Todd. 

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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] Checking vfd hookup question?

[Todd Zuercher]

I doubt you'd really need a braking resistor for running a router spindle (what 
I believe you have.)  Simply test it without one, as long as you don't get 
overvoltage alarms on the VFD when decelerating you should good without it 
(assuming your VFD has adequate safety alarms which might be a big assumption 
with a Chinese piece.)  
I've not run into a machine that uses one myself, but I only work with large 
commercial router machines. (not any mills or lathes) and router spindles don't 
have the rotating inertia that other machines like a lathe might or the need to 
stop super fast. 

Todd Zuercher
P. Graham Dunn Inc.
630 Henry Street 
Dalton, Ohio 44618
Phone:  (330)828-2105ext. 2031

-Original Message-
From: Jon Elson  
Sent: Tuesday, December 22, 2020 8:51 PM
To: Enhanced Machine Controller (EMC) 
Subject: Re: [Emc-users] Checking vfd hookup question?

[EXTERNAL EMAIL] Be sure links are safe.

On 12/22/2020 06:30 PM, Matthew Herd wrote:
> In my research on resistor sizing, I heard reports that Haas uses stove 
> elements for their braking resistors.  On factory machines, no less.  Of 
> course that’s second hand, so I can’t say it’s true.
>
>
Yes, absolutely.  Our Haas at work has a stovetop element in a screen guard on 
the back of the machine.
All of them are made like that.  It is a perfect solution for a 240 V machine.  
But, for the smaller VFDs you want a small stovetop element so it doesn't draw 
excessive current.  Assuming a voltage doubler on a
120 V VFD, it will still have 340V or so DC on the DC link, same as a 240 V 
VFD.  A 40 Ohm element should draw less than
10 A, which should be safe for anything but the smallest VFD.  So, get the 7" 
stovetop elements, not the 11" ones.

Using too low a resistance won't harm the MOTOR, it will blow the power brick 
in the VFD.

Jon


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Re: [Emc-users] Checking vfd hookup question?

[Ralph Stirling]

Yes, it is true.  The Haas TM-1 mill we used to have used a
stovetop element in a cage on top of the control.  There may
have been a fan on the cage, but I don't recall.  We were
able to replace the TM-1 with a Mori NVX which I like better :-).

-- Ralph

From: Matthew Herd [herd.m...@gmail.com]
Sent: Tuesday, December 22, 2020 4:30 PM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] Checking vfd hookup question?

CAUTION: This email originated from outside the Walla Walla University email 
system.


In my research on resistor sizing, I heard reports that Haas uses stove 
elements for their braking resistors.  On factory machines, no less.  Of course 
that’s second hand, so I can’t say it’s true.

> On Dec 22, 2020, at 7:15 PM, Chris Albertson  
> wrote:
>
> I knew some one who found he could use a stove heating element as a load.
> They are cheap


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Re: [Emc-users] Checking vfd hookup question?

[Jon Elson]

On 12/22/2020 06:30 PM, Matthew Herd wrote:

In my research on resistor sizing, I heard reports that Haas uses stove 
elements for their braking resistors.  On factory machines, no less.  Of course 
that’s second hand, so I can’t say it’s true.


Yes, absolutely.  Our Haas at work has a stovetop element in 
a screen guard on the back of the machine.
All of them are made like that.  It is a perfect solution 
for a 240 V machine.  But, for the smaller VFDs you want a 
small stovetop element so it doesn't draw excessive 
current.  Assuming a voltage doubler on a
120 V VFD, it will still have 340V or so DC on the DC link, 
same as a 240 V VFD.  A 40 Ohm element should draw less than 
10 A, which should be safe for anything but the smallest 
VFD.  So, get the 7" stovetop elements, not the 11" ones.


Using too low a resistance won't harm the MOTOR, it will 
blow the power brick in the VFD.


Jon


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Re: [Emc-users] Checking vfd hookup question?

[Gene Heskett]

On Tuesday 22 December 2020 18:43:08 Ralph Stirling wrote:

> Yes, the DCM terminal is the digital common for FWD and REV.

Good, that how I hooked it up but haven't powered it yet. I generally rig 
my stuff with a couple 40 amp SSR's to control motor power from the F2 
key. But that cable is not hooked up yet.

> That works fine on my system (that I'm working on as I write).
> What did not work for me was the UPF and DRV outputs that
> also use the DCM common.  Those are supposed to be open
> collector outputs that can be used for spindle-at-speed, spindle-
> stopped, or running indications.  Neither output works on my
> system at all.  I gave up and did a sets spindle-at-speed 1.

Open collector would mean they need a pullup.  Not all Mesa cards do 
that. But some also offer a low resolution 8 bit A/D on the first 4 
digital inputs that might be read and scaled to do similar functions, I 
think on the 110 volter lashup I was doing the sets trick too.

I wonder if there is a register that controls the type of signal that 
open collector sends?  I've TBT, not sat down and read the booklet for 
such details.  Me Bad dog...

> -- Ralph

Take care and stay well, Ralph.

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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-users] Checking vfd hookup question?

[Matthew Herd]

In my research on resistor sizing, I heard reports that Haas uses stove 
elements for their braking resistors.  On factory machines, no less.  Of course 
that’s second hand, so I can’t say it’s true.

> On Dec 22, 2020, at 7:15 PM, Chris Albertson  
> wrote:
> 
> I knew some one who found he could use a stove heating element as a load.
> They are cheap


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Re: [Emc-users] Checking vfd hookup question?

[Matthew Herd]

For my 1.5kw Hitachi WJ200 drive, the manual recommends 50 ohm.  However,
they want you to buy their resistor so they don't spec a recommended
wattage.  I ended up using a 400W wirewound resistor from Ohmite, part
number ARG400C50RJ.  It didn't even get warm when I was running my rigid
tapping testing with back to back reversals and the shortest ramp times
that gave reliable performance.  I'd think 400-600W should be ample for a
normal duty cycle, even on a 2.2kW drive with aggressive ramp times.

On Tue, Dec 22, 2020 at 7:18 PM Chris Albertson 
wrote:

> The brake resister depends on what duty cycle you run the motor at.   It
> you only run forward at a constant speed you will never use the resister.
>   But if you continuously run the motor to full forward then full backward
> speed for hours you will be heating the resister with about 50% of the
> motor's full power  So over 1KW.   Then add a "safety factor" or say 1.5
> and you get a 1.5KW resistor.  But I doubt you'd do a worst-case back and
> forth motion.
>
> One way to save a few $$ is to install a fan in the resistor with a
> thermostat. The best load resisters I found per dollar are those ones
> on eBay made with wires over a ceramic tube.   Buy several and you can
> adjust the resistance by writing series/parallel in different combinations.
>
> A low resistance will be a more effective brake.  But do not go too low.
> Calculate the current.   If the motor has 200 volts across it and you sort
> the leads through a 1 ohm resistor then you get 200 amps and maybe the
> motor is only rated at 20 amps and you blow up the motor.
>
> The most efftive brake is a length of wire.  The worst one is an open
> circuit.   I think maybe a compromise is to use a resister then same
> inpedence as the motor.
>
> I knew some one who found he could use a stove heating element as a load.
> They are cheap
>
> Wild guess?maybe 50R at 1 KW peak with much lower average W ratiing.
>
>
>
>
> On Tue, Dec 22, 2020 at 3:25 PM Gene Heskett  wrote:
>
> > Greetings all;
> >
> > Swapping a 110 volt vfd, for a 250 volt vfd, one of the terminals is
> > labeled differently, the common point of the fwd/rev/spd1-2-3-4-5
> > terminals on the 110 volter is labeled XGND
> >
> > But the common point terminal on the higher voltage unit is labeled DCM
> > but the diagram of how to hook up external controls is identical.
> >
> > Is there any good reason to treat it differently in hooking it to a
> > 7i76D? It should all be equ as its the presence of continuity from the
> > fwd/rev terminals to this XDNG/DCM common point that determines the
> > command.
> >
> > There is no terminal labeled neutral on this controller, only a marked
> > static ground which I ran back to the services static bar, not to the
> > neutral bar.  But my copy of the NEC is now 24 years old, so I'm asking,
> > hopefully, someone with a more recent copy.
> >
> > This is also the first vfd I've had that actually has hookups for a dump
> > resistor. 2.2 kw vfd & motor, running on 250 volt single phase, what is
> > good value and wattage for this resistor?
> >
> > Thanks folks.
> >
> > 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)
> > If we desire respect for the law, we must first make the law respectable.
> >  - Louis D. Brandeis
> > Genes Web page 
> >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
>
> ___
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>


-- 
Matthew Herd
Email:  herd.m...@gmail.com
Cell:  610-608-8930

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Re: [Emc-users] Checking vfd hookup question?

[Chris Albertson]

The brake resister depends on what duty cycle you run the motor at.   It
you only run forward at a constant speed you will never use the resister.
  But if you continuously run the motor to full forward then full backward
speed for hours you will be heating the resister with about 50% of the
motor's full power  So over 1KW.   Then add a "safety factor" or say 1.5
and you get a 1.5KW resistor.  But I doubt you'd do a worst-case back and
forth motion.

One way to save a few $$ is to install a fan in the resistor with a
thermostat. The best load resisters I found per dollar are those ones
on eBay made with wires over a ceramic tube.   Buy several and you can
adjust the resistance by writing series/parallel in different combinations.

A low resistance will be a more effective brake.  But do not go too low.
Calculate the current.   If the motor has 200 volts across it and you sort
the leads through a 1 ohm resistor then you get 200 amps and maybe the
motor is only rated at 20 amps and you blow up the motor.

The most efftive brake is a length of wire.  The worst one is an open
circuit.   I think maybe a compromise is to use a resister then same
inpedence as the motor.

I knew some one who found he could use a stove heating element as a load.
They are cheap

Wild guess?maybe 50R at 1 KW peak with much lower average W ratiing.




On Tue, Dec 22, 2020 at 3:25 PM Gene Heskett  wrote:

> Greetings all;
>
> Swapping a 110 volt vfd, for a 250 volt vfd, one of the terminals is
> labeled differently, the common point of the fwd/rev/spd1-2-3-4-5
> terminals on the 110 volter is labeled XGND
>
> But the common point terminal on the higher voltage unit is labeled DCM
> but the diagram of how to hook up external controls is identical.
>
> Is there any good reason to treat it differently in hooking it to a
> 7i76D? It should all be equ as its the presence of continuity from the
> fwd/rev terminals to this XDNG/DCM common point that determines the
> command.
>
> There is no terminal labeled neutral on this controller, only a marked
> static ground which I ran back to the services static bar, not to the
> neutral bar.  But my copy of the NEC is now 24 years old, so I'm asking,
> hopefully, someone with a more recent copy.
>
> This is also the first vfd I've had that actually has hookups for a dump
> resistor. 2.2 kw vfd & motor, running on 250 volt single phase, what is
> good value and wattage for this resistor?
>
> Thanks folks.
>
> 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)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] Checking vfd hookup question?

[Dave Cole]

Is this a Chinese drive?  I have seen a lot of strange nomenclature on 
Chinese drives.


M in a German sense, oftentimes denotes "mana" which is a common.  I 
have seen M or "mana" used to denote a low voltage common.   So does the 
M in DCM, stand for "mana"? Perhaps?  Perhaps the drive was designed by 
a German engineer?


I try to look at the example wiring diagrams as those seems to be fairly 
consistent even though the nomenclature is often not.


A neutral connection should not be required.

Since you are in the US and likely on a 240 single phase residential 
service, so you likely just have two hot legs which is 240/250 volts, 
and those would connect to the drive along with the safety ground.


I would think that your drive manual should have a resistor 
recommendation for the dump resistor.   Or maybe not?


A dump / braking resistor is only required if you want to stop the motor 
quickly.


Dave



On 12/22/2020 6:23 PM, Gene Heskett wrote:

Greetings all;

Swapping a 110 volt vfd, for a 250 volt vfd, one of the terminals is
labeled differently, the common point of the fwd/rev/spd1-2-3-4-5
terminals on the 110 volter is labeled XGND

But the common point terminal on the higher voltage unit is labeled DCM
but the diagram of how to hook up external controls is identical.

Is there any good reason to treat it differently in hooking it to a
7i76D? It should all be equ as its the presence of continuity from the
fwd/rev terminals to this XDNG/DCM common point that determines the
command.

There is no terminal labeled neutral on this controller, only a marked
static ground which I ran back to the services static bar, not to the
neutral bar.  But my copy of the NEC is now 24 years old, so I'm asking,
hopefully, someone with a more recent copy.

This is also the first vfd I've had that actually has hookups for a dump
resistor. 2.2 kw vfd & motor, running on 250 volt single phase, what is
good value and wattage for this resistor?

Thanks folks.

Cheers, Gene Heskett



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Re: [Emc-users] Checking vfd hookup question?

[Ralph Stirling]

Yes, the DCM terminal is the digital common for FWD and REV.
That works fine on my system (that I'm working on as I write).
What did not work for me was the UPF and DRV outputs that
also use the DCM common.  Those are supposed to be open
collector outputs that can be used for spindle-at-speed, spindle-
stopped, or running indications.  Neither output works on my
system at all.  I gave up and did a sets spindle-at-speed 1.

-- Ralph

From: Gene Heskett [ghesk...@shentel.net]
Sent: Tuesday, December 22, 2020 3:23 PM
To: Enhanced Machine Controller (EMC)
Subject: [Emc-users] Checking vfd hookup question?

CAUTION: This email originated from outside the Walla Walla University email 
system.


Greetings all;

Swapping a 110 volt vfd, for a 250 volt vfd, one of the terminals is
labeled differently, the common point of the fwd/rev/spd1-2-3-4-5
terminals on the 110 volter is labeled XGND

But the common point terminal on the higher voltage unit is labeled DCM
but the diagram of how to hook up external controls is identical.

Is there any good reason to treat it differently in hooking it to a
7i76D? It should all be equ as its the presence of continuity from the
fwd/rev terminals to this XDNG/DCM common point that determines the
command.

There is no terminal labeled neutral on this controller, only a marked
static ground which I ran back to the services static bar, not to the
neutral bar.  But my copy of the NEC is now 24 years old, so I'm asking,
hopefully, someone with a more recent copy.

This is also the first vfd I've had that actually has hookups for a dump
resistor. 2.2 kw vfd & motor, running on 250 volt single phase, what is
good value and wattage for this resistor?

Thanks folks.

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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 
<https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fgeneslinuxbox.net%3A6309%2Fgenedata=04%7C01%7Cralph.stirling%40wallawalla.edu%7C54f6924228d0410e642f08d8a6d09edb%7Cd958f048e43142779c8debfb75e7aa64%7C0%7C0%7C637442762249729745%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000sdata=04nRbfqvir2AIh7e15HIRDgKdY1OLfCMxVVUOWkwtGU%3Dreserved=0>


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[Emc-users] Checking vfd hookup question?

[Gene Heskett]

Greetings all;

Swapping a 110 volt vfd, for a 250 volt vfd, one of the terminals is 
labeled differently, the common point of the fwd/rev/spd1-2-3-4-5 
terminals on the 110 volter is labeled XGND

But the common point terminal on the higher voltage unit is labeled DCM 
but the diagram of how to hook up external controls is identical.

Is there any good reason to treat it differently in hooking it to a 
7i76D? It should all be equ as its the presence of continuity from the 
fwd/rev terminals to this XDNG/DCM common point that determines the 
command.

There is no terminal labeled neutral on this controller, only a marked 
static ground which I ran back to the services static bar, not to the 
neutral bar.  But my copy of the NEC is now 24 years old, so I'm asking, 
hopefully, someone with a more recent copy.

This is also the first vfd I've had that actually has hookups for a dump 
resistor. 2.2 kw vfd & motor, running on 250 volt single phase, what is 
good value and wattage for this resistor?

Thanks folks. 

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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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