Question

How long do brushes last in a generator?

Answer 1

1. The coils of the rotor must be connected to form an electrical circuit in order for some kinds of electric motors or generators to work. Originally, to achieve this, a copper or brass commutator or "slip ring" was attached to the shaft. Then, using springs, the commutator or slip ring would carry the current by brushing braided copper wire onto it. These brushes short-circuited adjacent segments, causing them to arc and even fuse together when the commutator turned.
2. The solution was the development of graphite-made "high resistance brushes" (sometimes with added copper). Despite being of the order of tens of milliohms, the resistance was high enough to allow a smooth transition of current from one commutator segment to the next.
3. There are four basic grade types of carbon brushes: carbon graphite, electrographic graphite, graphite, and metal graphite. The word "brush" is still in usage. Since brushes deteriorate over time, they can be changed into items designed to facilitate maintenance.

A brush or carbon brush is an electrical sliding contact, which transfers current between stationary wires and moving parts, most commonly in a rotating shaft.

1. Function of brushes is to collect the current from the coil and transfer it to the load connected to the circuit of the electric generator.
2. An estimated life of brushes in a generator, for general purpose, medium horsepower DC motors is up to $7,500$ hours.
3. The average life of a brush lies between $2,000$ to $5,000$ hours with $10,000$ hours being the maximum period.

To maximize the life of a brush, follow the following steps:

1. No air filter cover and filter, should be used, remove if any.
2. No plastic or metal cover over brushes is used, remove if any.
3. Mark the top wire on the brush block (holder) and the top of the brush block.