Synchronous generator or Alternator

Alternator is a machine which converts the mechanical energy into electrical energy at particular voltage with a fixed frequency.

The frequency is an important property of A.C Electrical energy. Frequency depends on the speed. To achieve fixed frequency the machine must be always driven only at one speed, called the synchronous speed. That’s reason these machines are called synchronous machines.

Principle of operation

Whenever there is a relative space (or) time variation between magnetic field and conductor, an emf will be induced in that conductor. This is the Faraday’s law of Electro Magnetic Induction. The magnitude of induced emf is E = BlV Sinθ


θ = Angle between B and direction of motion of conductor (also V).

V = Velocity of conductor (m/sec)

B = Flux density (Tesla or Wb/m²)

l  = Active length of conductor (m)

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