Question

A pilot exciter is provided on generators for which of the following reasons?
1. To excite the poles of the main exciter
2. To provide requisite starting torque to the generator
3. To cancel the ripple frequency
4. To provide requisite starting torque to the main exciter

Answer 1

Correct Answer - Option 1 : To excite the poles of the main exciter

To excite the field winding of the rotor of the synchronous machine, direct current is required. Direct current is supplied to the rotor field of the small machine by a DC generator called exciter. A small DC generator called pilot generator, supplies the current to the exciter.

Pilot exciter:

• A pilot exciter is a small AC generator with a permanent magnet mounted on the rotor shaft and the three phase winding on the stator.
• It provides the field current of the exciter. The exciter supplies the field current of the main machine.
• The DC output of the main exciter is given to the field winding of the synchronous machine through brushes and slip rings. The pilot exciter is excluded in smaller machines.