Chapter 10 - AC Generator Construction

Question 1

Explain the advantages of the Brushless Generator over the Conventional Generator?

Answer 1

The Slip Rings, Commutator, & Brushes of the conventional generator reduces it reliability and because the Brushless Generator has non of these it is more reliable

Question 2

List 2 Types of generator rotor and their application in the R.N?

Answer 2

The R.N uses the

1. Salient Pole Rotor (Used in all H.M Ships except Submarines)
2. Cylindrical Rotor (Used in Submarines)

Question 3

Describe the Salient Pole Rotor?

Answer 3

Salient pole rotors are constructed with a short Axial length and large diameter (Producing Compact Generators).
The Pole pieces are fixed to the rotor shaft and are made of laminated steel.
The Field Coils are wound around the pole pieces.

Question 4

Describe the Cylindrical Rotor?

Answer 4

The Cylindrical Rotor has a circular cross section with the field winding’s set in slots on the surface of the rotor.
These rotors have a long axial Length. which in turn makes the generator longer.

Question 5

Explain how the field current is applied to the rotor of the Conventional Generator?

Answer 5

A DC Generator, called the Exciter produces the excitation current to the rotor via the exciter commutator and a set of Slip Rings

Question 6

Explain how the field current is applied to the rotor of the Brushless Generator?

Answer 6

The exciter for a brushless Generator is a 3 phase AC Generator mounted on the main generator rotor shaft and includes a shaft mounted 3 phase full wave bridge rectifier to convert the exciter output to DC for the main field.