Slip ring wear

[duke37]

My brother has a three phase generator which was involved in a fire. I replaced burnt out wires and a three phase rectifier. It works, glory be !

I have noticed that one slip ring is badly worn and the other is almost like new. I assume the difference is due to the different polarity. I would like to connect the brushes to reduce the wear on the worn slip ring.

Will the positive or negative brush wear the commutator the most ?

 

[shrtrnd]

I don't THIINK the polarity has anything to do with it.
I would assume it's physical wear from the commutator.
Do you see any scrap marks or uneven wear at the slip rings?
Is the bearing at that end worn, and allowing excessive play in the shaft that's
wearing the outside slip ring more than the inside one?