You should still check the field volts when started.
Also, armature volts. It may be lack of L contactor pickup.
Brushes usually don't disconnect at once but it could be. You need to
pull the motor apart to inspect/replace them which is not all that hard
but putting it together takes some skill as you have to assemble the
motor endshield while pulling the brushes back to move them far enough
apart to slide the rotor in. I've pulled them apart, blown them out,
inspected and replaced brushes.....but I've also had 30 years at GE
working on them.
If you have a small local shop, it may be better for you to take it
there and watch them do it....ask for a quote or fixed price to
check/inspect....don't let them hi-pot the windings.
Make sure the control is not the problem first unless you want to check
the motor out anyways.
...Walt
-----Original Message-----
From: Steve Gaarder [mailto:gaarder ecovillage ithaca ny us]
Sent: Monday, January 26, 2009 9:36 AM
To: Konstanty, Walter (GE Indust, ConsInd)
Cc: elec-trak cosmos phy tufts edu
Subject: RE: (ET) Motor trouble
Thanks for the suggestions. The current draw is very small, so I figure
that the problem is not the field. Also, the one time I had a field
supply failure, the motor did turn, but ran fast with little torque.
No smoke or any heating that I've noticed.
Could this be a problem with the brushes? Can they be changed without
pulling the motor?
thanks,
Steve Gaarder
On Mon, 26 Jan 2009, Konstanty, Walter (GE Indust, ConsInd) wrote:
Steve,
Basic motor troubleshooting:
- drive motor has shunt field (2 smaller wires)
- power must be applied to shunt field to run and voltage is stepped
with large contactors to the armature (2 larger leads)
- finger relay reverses shunt field polarity and motor direction for
F-R
- if power gage is pegging and motor not turning, field is bad or
probably not getting power from relay (those finger relays are
notorious for sticking or arcing)
check relays, sand connections, make sure they are working.
Shunt field is approx 17 ohms
- VR-1 on card 3 (reddish disc) may also be burned up....it absorbs
voltage when relay reversed for direction
So, make sure field has 36VDC when starting....monitor field and
armature voltage. If motor is bad, I'd suspect armature is shorted or
grounded and you'd smell it. Pulling motor is not fun so check
control first which is 95% of normal problems on E15.
...Walt
-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of Steve
Gaarder
Sent: Monday, January 26, 2009 9:09 AM
To: elec-trak cosmos phy tufts edu
Subject: (ET) Motor trouble
Our E-15 is running intermittently. There seems to be voltage on the
two large motor connections when it's not running,so I figure the
problem must be in the motor. Am I overlooking anything? If not, I
will pull the motor and take it to the local motor shop. Is there
anything I should tell them about these motors?
thanks,
Steve Gaarder
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