Page 31 - Basics of Electrical, Electronic and Communication

136 Chapter 7. DC machines

7.2 Principle of dc Generator

A dc generator is a rotating machine which converts mechanical energy
into electrical energy. DC generators work on the principle of electro-
magnetic induction. According to Faraday’s law of electromagnetic
induction, whenever a conductor cuts magnetic lines of flux a dynamic
emf is induced in the conductor. This emf causes a current flow if the
circuit is closed. The essential requirements of a dc generator are

1. A magnetic field

2. Conductors or coils

3. Relative motion between the magnetic field and the conductors

7.3 Simple loop generator

Shaft

A
D

B
C

G Galvanometer

M L

Figure 7.2: A simple loop generator

136