Q & A

Alternator differ from a D.C Generator?
produce 3 phase A.C supply
Stator:Contains Armature winding
Rotor:Contains field winding

Why 3 phase alternator generally star connected?
Requires less number of turns when star connected
Requires less insulation
Undesired harmonics can be avoided

What are turbo alternators?
The alternators which is build in non salient pole construction and having small no. of poles to get high speed is called turbo alternators.

DC GENERATOR

Dc generator are not widely used, since most of the appliances works on AC. But the study of DC Generator is important to under stand the concept of other DC machine.

Basic principle:

# Right hand thumb rule

~Thumb: Direction of motion of conductor.

~Fore finger: Direction of field

~Middle finger: Direction of induced emf.

#Types
1. separately excited:
rarely used in practice

2. Self exited :
There are of three types
a. Series
b. Shunt
c. Compound

EMF equation:

EMF = P¤ZN/60A

P= No of poles
¤=flux in weber
Z = No of conductors
N = speed in rpm
A = No of parallel paths = 2 wave winding ,P for lap winding.