generator brush gear sparking problem 3

[tinashe8]

hello there, what causes generator brushgear to spark and the rotating exciters to burn? what do you recommend to overcome these problems? thank you for your help!

 

[waross]

1> Wrong grade of brush.
2> Brushes sticking in the brush holders.
3> Excess current.
For slip rings;
4> Slip rings dirty.
5> Slip rings out of round. Possible short or multiple grounds in the field.
For commutators;
6> Brushes shifted off of electrical neutral position.
7> Faulty compensating fields/poles.
8> Possible short or multiple grounds in armature or the field(s).

Bill
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"Why not the best?"
Jimmy Carter

 

[RoyDoug]

I agree with all waross said and add the following:
The sparking and burning on the commutator of the DC Exciters is most likely the cause of the subsequent sparking on the slip-ring brushes.
DC Exciters operating correctly will provide a smooth DC current to the excitation slip-rings of the generator.
Check the DC waveform being generated on an oscilloscope.
Burnt commutators indicate DC Exciter issues (neutral, compole problems etc!... )resulting in deformation of the commutators and poor quality DC to the generator.
There are modern instruments available to measure commutator deformation with both contact and non-contact methods.
Smooth it all out.
RD