ABB DCS 500B - DC-Motor Neutral Zone Adjustment; Types Concerned; Summary; General

Chapter 10 - Service
DCS 500 / DCS 600 Service Manual
VI A 10 - 5
DC-Motor neutral zone adjustment
Types concerned
DC-Motors
Summary
Procedure to adjust the neural zone of a DC-motor
General
- Loosen the bolts holding the brush bridge.
- Connect a scope or a voltmeter between two adjacent brush-
holder assemblies (holders with different polarity).
- Set the scaling on the scope or voltmeter to mV AC.
- Disconnect the excitation cables and connect 110 – 240 VAC
between F+ and F- (a normal extension cord is sufficient).
- Start moving the brush bridge slowly in one direction and watch
the scope or voltmeter. If the voltage is increasing move the
brush bridge in the other direction.
- Try to get the voltage down to less than 50mV AC. The less the
better.
- When this is achieved, start tightening the brush bridge bolts
and watch the voltage. Sometimes you have to do a little offset
to compensate for movements during tightening.
- Finally, mark the correct neutral zone position in case the motor
will be taken apart in the future.
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