CAD CAM EDM DRO - Yahoo Group Archive

Re: [CAD_CAM_EDM_DRO] Powerdump relay (now with free arcwelding)

Posted by David Speck
on 2005-08-25 09:37:02 UTC
Abby,
I assume you are dumping your power supply to stop the motors in an
emergency error condition.

Instead of shorting out the power supply, you might rewire your circuit
to simply break the connection between the power supply and the motors.
The motors will still stop, and you won't have the heavy current dump
through the relay. You still have to use a beefy contactor. I just
bought one off eBay last night rated at 90 amps for $10.00. Look around
--- there are a lot to choose from.

Note, however, that some drive systems have braking capability built in,
and if you short the power supply, or disconnect it, then the braking
capability will go away, and the machine may coast farther than it would
have with a more controlled stop. You'll have to check out the specs of
your driver systems.

Dave

Abby Katt wrote:

>Hi all,
>
>I have a RELAY configuration on my PSU whereby the power being shut off
>(E-stop / limits / etc) causes the transformer to be disconnected and
>the capacitor to be dumped through a power resistor. The problem I am
>getting is that the relay has been arc-welding itself in the ON-Position
>(and lately in the off-position).
>The old RELAY was rated 20A, and the PSU was a 55V/500W linear one, with
>the power resistor calculated to dissipate 10A.
>
>I'm about to install a relay rated at 30A N.O and 3A NC (The best I can
>seem to find for this voltage range) and was wondering if I could use
>some of the capacitors I have spare for preventing DC brush-motor
>spikes, to somehow limit the arcing?
>
>Any advice?
>Thanks!
>Abby
>
>

Discussion Thread

biswanath55 2005-08-23 20:47:59 UTC Newbie - Help & Clarifications Jim Peck 2005-08-24 03:00:16 UTC RE: [CAD_CAM_EDM_DRO] Newbie - Help & Clarifications Fred Smith 2005-08-24 05:54:30 UTC Re: Newbie - Help & Clarifications wanliker@a... 2005-08-24 09:39:19 UTC Re: [CAD_CAM_EDM_DRO] Re: Newbie - Help & Clarifications Lance Hopper 2005-08-24 11:50:02 UTC Re: Newbie - Help & Clarifications Blue 2005-08-24 15:21:20 UTC Re: [CAD_CAM_EDM_DRO] Newbie - Help & Clarifications caedave 2005-08-24 16:30:32 UTC Re: [CAD_CAM_EDM_DRO] Newbie - Help & Clarifications Blue 2005-08-24 18:24:54 UTC Re: [CAD_CAM_EDM_DRO] Newbie - Help & Clarifications caudlet 2005-08-24 21:03:53 UTC Re: Newbie - Help & Clarifications Andrey Lipavsky 2005-08-24 21:20:44 UTC RE: [CAD_CAM_EDM_DRO] Newbie - Help & Clarifications caedave 2005-08-25 01:39:14 UTC Re: [CAD_CAM_EDM_DRO] Newbie - Help & Clarifications Abby Katt 2005-08-25 06:07:51 UTC Powerdump relay (now with free arcwelding) turbulatordude 2005-08-25 06:16:00 UTC Re: Newbie - Help & Clarifications - Home and Limit Swtiches Les Newell 2005-08-25 06:20:06 UTC Re: [CAD_CAM_EDM_DRO] Powerdump relay (now with free arcwelding) Andy Wander 2005-08-25 06:33:35 UTC RE: [CAD_CAM_EDM_DRO] Powerdump relay (now with free arcwelding) lcdpublishing 2005-08-25 07:25:54 UTC Re: Newbie - Help & Clarifications - Home and Limit Swtiches John Johnson 2005-08-25 07:52:53 UTC Re: [CAD_CAM_EDM_DRO] Powerdump relay (now with free arcwelding) caudlet 2005-08-25 08:35:07 UTC Re: Powerdump relay (now with free arcwelding) David Speck 2005-08-25 09:37:02 UTC Re: [CAD_CAM_EDM_DRO] Powerdump relay (now with free arcwelding) David A. Frantz 2005-08-25 10:15:34 UTC Re: [CAD_CAM_EDM_DRO] Newbie - Help & Clarifications Fred Smith 2005-08-25 12:42:24 UTC Re: Newbie - Help & Clarifications David A. Frantz 2005-08-25 14:21:25 UTC Re: [CAD_CAM_EDM_DRO] Re: Newbie - Help & Clarifications Fred Smith 2005-08-25 16:06:13 UTC Re: Newbie - Help & Clarifications lcdpublishing 2005-08-25 17:04:12 UTC Re: Newbie - Help & Clarifications wanliker@a... 2005-08-25 17:07:27 UTC Re: [CAD_CAM_EDM_DRO] Re: Newbie - Help & Clarifications wthomas@g... 2005-08-26 20:47:00 UTC Re: [CAD_CAM_EDM_DRO] Newbie - Help & Clarifications