Electric Generator

 Introduction

Electric generator is a machine that converts mechanical energy to electricity for transmission and distribution over power lines to domestic , commercial and industrial customers.It is also called dynamo.It produce electrical power required for automobiles, aircrafts,train and ships.Reverse conversion of electrical energy to mechanical energy is done by electric motor.

Fig: Electric generator 

History of electric Generator 

Electrostatic generators were used before the relationship between electricity and magnetism was discovered.These are operated according to Electrostatic principles.But they are never used for generation of  commercial electric power production due to following reasons:

• Due to difficulty in insulating machines that produce high voltages.
• Due to low power rating.

Due to this inefficiency of electrostatic generators the first electro magnetic generator ,the faraday disk,was invented in 1831 by British scientist Michael faraday.

Working principle of Electric Generator

An electric generator is a device that converts mechanical energy obtained from an external source into electrical energy as output.It is important to understand that a generator doesn’t actually ‘create’ electrical energy.Instead ,it uses the mechanical energy supplied to it to force the movement of electric charges present in the wire of it’s windings through an external electric circuit.This flow of electric charges constitutes the output electric current supplied by the generator.This mechanism can be understood by considering generator as water pump,which causes the flow of water but doesn’t actually ‘create’ the water flowing through it.

The modern -day generator works on the principle of electromagnetic induction discovered by Michael faraday in 1831-32.Faraday discovered that  the above  flow of electric charges could be induced by moving an electrical conductor,such as a wire that contains electric charges,in a magnetic field.This movement creates voltage difference between the two ends of the wire or electrical conductor,which in turn causes the electric charges to flow,thus generating electric current.

Components of an Electric Generator 

Fig: Components of Electric Generator

1. Frame: It is the structure of electric generator.
2. Cooling system:It regulates heat that build up in the system.
3. Fuel system:It keeps generator operational.
4. Engine:It is the source of mechanical energy.
5. Exhaust system:It is for disposal of waste exhaust gases produce in the process .
6. Voltage regulator:It regulates voltage output.
7. Alternator:It produces electrical output from mechanical input.
8. Battery charger:It keeps the battery of the generator charged.
9. Control panel:It controls generator interface .

Types of Electric Generators

The classification of electric generators depends on the type of electrical energy produced,which is either direct current or alternating current.

• Ac generators

Ac generators are known as single phase generators and are limited up to 25 kw.

• Dc generators

Dc generators are divided into three categories .They are shunt,series and compound – wound.Shunt generators are used in battery chargers.Series generators are used in street lights .While most of the DC generators are compound – wound.

Uses of Electric Generators

• They are used to drive motors.
• They are used in  transportation.
• Since they give range of output voltage so also used in labs.
• They provide power for most power networks of cities.
• Small scale generators provide a good back up for household power needs or small business.
• At construction sites, before the power is set up, they extensively make use of electric generators.