Pilot excitation system

Question

With the help of a suitable diagram describe pilot excitation system.

Answer 1

A pilot excitation system is an auxiliary arrangement used to excite the main exciter of a synchronous generator. It is part of a multi-stage excitation setup designed to ensure the reliability of the generator under dynamic and fault conditions. This system includes a small pilot exciter (a separately excited generator) that supplies DC or AC power to the field winding of the main exciter.

Components of Pilot Excitation System

1. Pilot Exciter:

   • A small generator, often directly coupled to the shaft of the synchronous machine.
   • It generates the field current for the main exciter.

2. Main Exciter:

   • Converts the current from the pilot exciter into field current for the generator rotor.

3. Synchronous Generator:

   • The main generator which generates electricity.

4. Voltage Regulator:

   • Ensures stable and precise control of the excitation system by adjusting the pilot exciter's output to regulate the generator voltage.

5. Rectifiers:

   • Converts AC output from the pilot or main exciter into DC if required for the synchronous machine's field winding.

Working Principle

1. The pilot exciter generates a small voltage/current, which is supplied to the main exciter's field winding.
2. The main exciter, powered by the pilot, produces the excitation current for the rotor of the synchronous generator.
3. This ensures proper synchronization and regulation of the main generator's output.

Diagram: