Differences between Motor and Generator

From working on the principle of electrostatics in the 1740s to today’s universal motors, electric motor and generators have evolved through a large number of changes. Although their hardware requirements are similar, motor & generator differ in their operational behavior. Today motors and generators have become a common electrical tool, used in almost every electrical appliance. Among themselves, motor and generator differ depending on their power source, type of winding used, brush or brushless, air cooled or water cooled. Before knowing their difference lets get familiarized with an electrical motor and electrical generator terms.

What is Electrical Motor and Generator?

The definitions of electrical motor and generator are discussed below. The motor is an electrical device which can convert electrical energy into mechanical energy, using the principles of electricity and magnetism. The motor contains the following.

Electrical Motor
Electrical Motor
  • Stator – the permanent magnets.
  • Rotor – the rotating part which contains conducting coils inside it,
  • Shaft – outputs the mechanical energy
  • Commutator – to apply alternating current to the rotor.
  • Brushes – To make contact between power supply and commutator.

Working Principle

When the power switched on, the brushes supply current to the commutators. These commutators are attached to the rotating coils, one to each end. Current passes from commutators into the coil, placed in between the poles of permanent magnets, stator. When current moves in the coil, the magnetic field is induced around the coil.

This magnetic field comes in contact with the magnetic field of the permanent magnets and due to the characteristic of the magnetism that like poles repel each other and unlike poles attracts, the coil starts to rotate. When the rotor rotates the shaft attached to it also rotates, thereby converting the applied electrical energy into mechanical energy.

Electric Generator

The device that can convert the mechanical energy to electrical energy is called a generator. The hardware requirements of the generator are the same but working principle differs. Here when the mechanical energy is applied to the shaft, the rotor rotates and this movement of the rotor between the permanent magnets starts generating electricity inside the coils of the rotor. This electricity is collected by the brushes.

Electrical Generator
Electrical Generator

Comparison between Electrical Motor and Generator

Electric Motor

Electric Generator

Generates mechanical energy from electrical energy.


Generates electrical energy from mechanical energy
Electricity is required for its operation.


It generates electricity.


Flemings left-hand rule is followed to know the direction of motion.


Fleming’s right-hand rule is followed to know the direction of produced electricity.


Source of energy is power grids, electrical supply.


Source of energy are steam turbines, water turbines, internal combustion engines.


Motors are used in Automobiles, elevators, fans, pumps, etc Generators are used in power supply chains in industries, testing purpose in the laboratory, general lighting, powering of batteries, etc

Difference between the AC Motor and the DC Motor

  • In the AC motor, the source of power is AC mains supply whereas in DC motor power is obtained from batteries.
  • In AC motors no commutators and brushes are used whereas in DC motors these plays an important part in their operation.
  • In AC motors the armature is stationary and the magnetic field rotates whereas in DC motors it is vice verse.
  • AC motors are suitable for large industrial applications whereas DC motors are suitable for domestic applications.

Difference between the AC Generator and the DC Generator

  • AC generator produces AC electrical power whereas DC generator produces DC electrical power.
  • In DC generator the current flows in one direction whereas in the AC generator current reverses periodically.
  • In DC generator split rings are used they wear out quickly whereas in AC generator slip rings are used, so they have high efficiency.
  • AC generators are used for small domestic applications whereas DC generators are used to power large motors.

These are the main differences between Motor and Generator. Based on the applications, requirements, and type of power supply choice is made between motors and generators. There are various types in AC motors and AC generators as well as in DC motors and DC generators. Some of the types in DC generators are shunt wound generator, series wound generators, etc. Can you name some types in DC motors?

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