MOTOR AND GENERATOR

 

MOTOR AND GENERATOR

 

Difference Between Motor and Generator

Sl. No.	Differentiating Property	Motor	Generator
1	Definition	An electric motor is a machine that converts electrical energy to mechanical energy.	An electric generator is a machine that converts mechanical energy to electrical energy.`
2	Rule	Electric motor follows Fleming’s left-hand rule.	Electric generator follows Fleming’s right-hand rule.
3	Principle	The working principle of a motor is based on the current-carrying conductor that experiences a force when it is kept in the magnetic field.	The working principle of generator is based on electromagnetic induction.
4	Driving force for shaft	The shaft of an electric motor is driven by a magnetic force which is developed between the armature and field.	The shaft of an electric generator is connected to the rotor which is driven by a mechanical force.
5	Current Usage	In a motor, current is supplied to the armature winding.	In a generator, current is produced in the armature winding.
6	Example	Ceiling fans, cars, etc. are all examples of motor.	In power stations, generator is used to generate electricity.

 

 

 

 

Electric motor

Electric Motor converts electrical energy into mechanical energy.

• Current enters arm AB through brush X and current flows through brush Y from C to D. Using Fleming’s LHR we find that the force pushes AB downwards and pushes CD upwards.
• In electric Motor the split rings PQ act as a commutator that reverses the direction of the current. The reversing of the current is repeated at each half rotation, giving rise to a continuous rotation of the coil.

Faraday’s experiment

• Faraday discovered that a magnetic field interacts with an electric circuit by inducing a voltage known as EMF (electromotive force) by electromagnetic induction.
• Moving a magnet towards a coil sets up a current in the coil circuit, as indicated by deflection in the galvanometer needle.

Electromagnetic induction

The phenomenon of electromagnetic induction is the production of induced EMF and thereby current in a coil, due to the varying magnetic field with time. If a coil is placed near to a current-carrying conductor, the magnetic field changes due to a change in I or due to the relative motion between the coil and conductor. The direction of the induced current is given by Fleming’s right-hand rule.

Fleming’s right-hand rule

According to Fleming’s right-hand rule, the thumb, forefinger and middle finger of the right hand are stretched to be perpendicular to each other as indicated below, and if the thumb indicates the direction of the movement of conductor, fore-finger indicating direction of the magnetic field, then the middle finger indicates direction of the induced current.

What is Generator?

A generator is a mechanical equipment which converts mechanical form of energy into electrical energy. Generators find application in agricultural and industrial production. The most widely used principle for the construction of generator is based on the law of electromagnetic force.

What is the Working Principle of Generator?

It consists of a rectangular coil with a number of copper wires wound over an iron core. The coil is called the armature. It is used to increase the magnetic flux. A strong permanent magnet is placed and the armature is rotated between the magnets where the magnetic lines are perpendicular to the axis of the armature. There are two slip rings connected to the arms of the armature. They are used to provide movable contact. Two metallic brushes are connected to the slip rings to pass current from the armature to the slip rings. The current is passed through a load resistance, which is connected across the slip rings.

At different time intervals, the position of the armature keeps changing. When the magnetic field lines are perpendicular to the coil, the coil is rotated in the magnetic field and the induced e.m.f produced increases. This happens in this position because of the number of intercepting magnetic field lines maximum.

What are the Types of Generators?

Following are the types of generators:

• AC generator
• DC generator

AC Generators

What are AC generators?

AC generators are also known as alternators which converts mechanical energy into electrical energy in the form of alternating current. 

DC Generator

What is DC generator?

A DC generator is used for converting mechanical energy onto direct current electricity.