DC and AC Motors

DC and AC Motors

Failure to start may be due to a break in the control circuit. Check protection devices such as fuses or circuit breakers. A frozen bearing can cause protection devices to activate. Supply line voltage should also be checked.

Sparking brushes on a commutator can indicate the need for reseating.

Resistors used in control circuits can fail due to overheating. Ventilation should be checked and improved if necessary.

Solid-state devices such as electronic soft starters can fail by opening or short circuiting. Replacement is usually the only option with electronic devices.

The feedback sensors of closed loop controllers can be a source of problems. Ensure the feedback path is not short- or open-circuited. Poor mechanical linkage of the sensor to the load can make the control erratic.

Poor electrical connections can cause intermittent faults.