Outlines:

Introduction

Construction

Working principle

Types of Synchronous Machine

Comparison between cylindrical rotor

type generator and Salient pole rotor

type generator

A synchronous machine is an AC machine whose speed is proportional to the frequency of armature current

A machine which rotates at a speed fixed by the supply frequency and the number of rotor poles is called synchronous machine

It always runs at synchronous or constant speed and has no slip

Synchronous machine includes synchronous generators and synchronous motors

2-Pole Salient Pole M/C 4-Pole Salient Pole M/C 4-Pole Cylindrical M/C

Cylindrical Rotor type

Synchronous GeneratorSalient Pole Rotor type

Synchronous Generator

A Synch. Generator consists of two main parts;

1) Stator and

2) Rotor

Stator:- The stator is the stationary parts part of the

Synch. Generator

It works as a armature in synchronous machine

The armature winding is housed in it

Rotor:

Rotor is the rotating part of the synchronous

machine

It work as a field of the synchronous machine

Field system is rotating in the synchronous

machine

Field winding is housed on it

Field winding is excited by DC supply through

brushes and slip ring

It works on the principle of Electromagnetic

induction

In the synchronous generator field system is

rotating and armature winding is steady.

Its works on principle opposite to the DC

generator

High voltage AC output coming from the

armature terminal

Generators:-Hydro-generators (Salient Pole Type): The Synchronous generators driven by water

turbines are known as hydro generators orWater wheel generators

They have rating upto 750 MW and are drivenat speeds ranging from 100 to 1000 RPM

Turbo-alternators (Cylidrical Rotor Type or Wound Rotor Type):

They are driven by steam turbines

The efficiency of steam turbine is high at largespeeds, the turbo-alternators are designed forspeed upto 3000 RPM. Turbo-alternators haveratings upto 1000MW

Engine Driven Generators: These generators are driven by different forms of

combustion engines at speed upto 1500 RPM andrating upto 20 MW

These generators are driven by gas turbines havehigher speeds and also higher power ratings

Motors:-Synchronous Motors: Synchronous motors may be either plain synchronous

machines or synchronous induction machines

The plain Synchronous machine with salient pole iscommonly used

Synchronous motors have some define advantagesover induction motors and these include constantspeed operation, Power factor control and highoperating efficiency

- Also Synchronous motors prove to be cheaperthan induction motors for high power lowspeed applications

- The applications of Synchronous machinesinclude constant speed drives forcompressors, blowers, low head pumps

Compensators:- Synchronous compensators are used for

control of reactive power in power supplynetworks

- They are designed for ratings upto 100 MVArand speed upto 3000 RPM

Synchronous generators are classified in two category according to its rotor construction:

1) Cylindrical Rotor Type

2) Salient pole Rotor Type

Cylindrical Rotor Type:-

This type machines are High speed machines (1000 to 3000 RPM)

This type machine has Small diameter and is large axial length

This type of machines are used in Thermal power plant and gas turbine power plant Where speed requires high

Field Pole

Field Winding

Damper

Windings

Damper Bars

Field Winding

Cylindrical rotor:-

Cylindrical rotor does not have poles that are projecting out.

The air gap between the stator and rotor is uniform.

The smooth cylindrical rotor has small no of poles.

Cylindrical rotors are mechanically strong.

They have small diameters and large axial length.

The prime movers used are steam turbines and electric motors.

They are preferred for high speed alternators which range from 1000 to 3000 RPM

Salient Pole rotor:-

Salient pole rotor does have poles that are projecting out from surface.

The air gap between the stator and rotor is non-uniform.

The salient pole rotor has large no of poles.

Saline Pole rotors are mechanically weak.

They have large diameters and small axial length.

The prime movers used are IC engines and law speed turbine.

They are preferred for law speed alternators which range from 100 RPM to 500 RPM

Query ???

Thank you !