# Synchronous Generator ( Alternator)

• An a.c generator, commonly referred to as synchronous generator or alternator, converts mechanical power into a.c. power.

• The term alternator is used because it produces a.c. power. It is called synchronous generator because it must be driven at synchronous speed NS (= 120 f/p)  to produce a.c. power of the desired frequency f.

• Thus for a 4-pole (i.e. P = 4) alternator to produce 50 Hz power, its speed of rotation must be 1500 mm (NS = 120 x 50/4 = 1500 r.p.m.).

• The synchronous generator can be either single-phase or a polyphase generator.

• Due to many technical and economic advantages, we always produce 3-phase power and hence the need for the 3-phase alternator (or 3-phase synchronous generator).

# Synchronous Generator ( Alternator) Diagram

[caption id="attachment_981" align="alignnone" width="1956"] Synchronous Generator[/caption]