Re: [CAD_CAM_EDM_DRO] Help, continuing to burn drives

You need to consider that the motor might be bad. Motors can
develop intermittent shorts in their windings. Gecko's,
like all chopper drives, require a certain minimum inductance in
the motor. When the windings short then the inductance can go
to zero. If this happens then the current will instantly exceed the
drives limit.

Sometimes motors develop a solid short. This can be detected
with an ohm meter. You need to know the correct resistance
to determine a bad motor. If you have a duplicate known good motor
then you can compare it. Often you can feel the difference by
turning the shaft by hand. Compare the suspect motor to a known
good motor. Completely disconnect the wires to both motors
and insulate the wires.

However, motor shorts can be intermittent. Some develop shorts
when they warm up but are fine when cold. Others are just the
opposite. This is very hard to test for. You can try to swap
drives to see if the problem moves with the motor. Unfortunately
this can cost a lot of money in dead drives. At some point
you have to say enough! and just change the motor.

Pete.

Ps; I assume that you have carefully checked the wiring. Intermittent
in the wiring can be just as fatal as intermittent in the motors.

----- Original Message -----
From: "Keith Clark" <mail@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Sunday, April 03, 2005 3:08 PM
Subject: [CAD_CAM_EDM_DRO] Help, continuing to burn drives


>
> Hi Guys, My bridgeport retrofit continues to burn Gecko drives. It
> happened just a few minutes ago when I powered up the machine and
> computer. The powersupply was plugged in but the relay controlling
> the powersupply was off. When I hit the button in the software to
> turn on the relay the Gecko immediately burned as did the protecting
> fuse. It always happens on the y axis when I first start up. It
> never seems to happen while running the machine. This is at least the
> fourth time this has occurred. Each time I think I have found the
> problem but alas, no. The last time was early Feb and then again
> last week. A new Gecko was installed thursday. It makes no sense
> why the thing would run for a month with no trouble. It think
> everything is installed correctly but there must be a powersurge from
> the powersupply when the relay first turns on. Is this a possibility
> and is there a way to protect from this?
>
> Thanks for any ideas!
>
> Keith Clark
>
>
>
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