Introduction of DC Machines

INTRODUCTION

DC Generator

An electrical generator is a rotating machine which converts mechanical energy into electrical energy. This energy conversion is based on the principle of electromagnetic induction. According to Faraday's laws of electromagnetic induction, whenever a conductor is moved in a magnetic field, dynamically induced emf is produced in the conductor.

When an external load is connected to the conductor the induced emf causes a current flow in the load. If a single conductor is used the emf produced is small. Large number of conductors used to obtain greater emf and the rotating conductor assembly is called an armature. Energy conversion is shown in Figure 2.1(a).

DC Motor

While a DC generator converts mechanical energy Figure 2.1(b) in the form of rotation of the conductor (armature) into electrical energy, a motor does the opposite. The input to a DC motor is electrical and the output is mechanical or torque. The fundamental principles and construction of the DC motors are identical with DC generators which have the same type of excitation. A DC machine that runs as a motor will also operate as a generator.