This document provides an overview of alternators, including: 1. Alternators convert mechanical energy to electrical energy by using a stator and rotor to generate an electromagnetic field and induce voltage in the armature windings. 2. Key components of an alternator include the stator, rotor, armature windings, and excitation system. The document describes different types of stators, rotors, and winding configurations. 3. Alternator voltage regulation, or the ability to maintain a constant output voltage under varying loads, is influenced by factors like armature resistance, leakage reactance, and load current. Methods to determine regulation include direct loading, EMF, and MMF techniques.

1. Introduction To Alternator
Definition - The device which converts mechanical energy into electrical energy
is known as a alternator.

2. Constructional features
• Main two parts
1.Stator or armature- cast iron
stator winding are housed in slots.
Type of slot- 1..Wide type 2.semi closed type 3. closed type
2.Rotor-
Type of rotor
1.Salient pole type rotor- Steel lamination
2. Smooth cylindrical type rotor- steel
Smooth Cylindrical
type Rotor
Salient pole type rotor

3. • Excitation system - 125 volt dc required to produce
required flux.
• Armature winding –
Placed in slots each having phase
difference of 120° connected in star or delta. Star is
preferred.

4. • Type of armature winding
1.Single layer & double layer
2.Full pitch & short pitch
3.Concentric &distributed
• Pitch factor – Kc always less than or equal to one.
It is the ratio of emf induced in short pitch winding to emf
induced in full pitch winding .
• Distribution Factor – Kd always less than or equal to one.
It is the ratio of emf induced in distributed winding to emf induced
in concentric winding
Kc = cos α/2
Kd= sin mβ/2
m sin β/2

5. Operational Features

6. Voltage regulation-
The voltage regulation of alternator is defined as
the change in terminal voltage when full load is removed
divided by rated terminal voltage.
% voltage regulation =
Factors affecting the regulations are-
1.armature resistance RA
2.leakage reactance XL
3.armature reaction reactance XA
4.magnitude of load current
5.power factor of load
100

Vt
VtEph

7. • Determination of voltage regulation
Following methods are used to determine the voltage
regulation –
1.Direct loading method
2.Synchronous method - EMF method
3. Ampere turn method -MMF method
• Parallel operation of Alternators
Conditions
1.Terminal Voltage
2.Frequency
3.Phase

8. Advantage of parallel operations of alternators
1.Rating
2.Continouty of service &high reliability
3.better efficiency
4.ease of maintenance
5.facility of extension
6.less costly
synchronizing of alternators
1.Lamp method
2.Synchronoscope method

9. Thank You …..
Have a nice day