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Starter Generator Brush Replacement

October 2013

Periodically, the brushes inside a starter generator will need to be replaced. For proper operation after being installed, the commutator needs to be reconditioned and the brushes should have an 8-16 hour overnight run-in. During the run-in, the brushes begin to fit to the form of the commutator and create a film resulting in better electrical contact.

Although not all starter generator manufacturers require this run-in, I highly recommend you make time for it, especially if the brushes are changed in the field.

If the brushes are installed without reconditioning the commutator or the brushes installed without proper contouring to the commutator and “run in,” you will find the unit to have short brush life and difficulty carrying the load demands with the normal field current draw from the voltage regulator. This can all be avoided by carefully performing reconditioning, seating and run in procedures.