Differences Between Electric Motors and Generators

In my next three posts, I’d like to compare several things to something similar. Today, the difference between electric motors and generators.

Electric Motor vs Generator

Electricity has become an inseparable part of our life; more or less our whole lifestyle is based on the electrical equipment. Energy is converted from many forms to the form of electrical energy, to power up all these devices. The electric motor is a device which converts mechanical energy into electrical energy. On the other hand, devices are used to transform electrical energy into mechanical as required. The motor is the device that performs this function.

More about Electric Generator

generator repair mini Differences Between Electric Motors and Generators

The fundamental principle behind the operation of any electrical generator is Faraday’s law of electromagnetic induction. Idea stated by this principle is that, when there is a change of the magnetic field across a conductor (a wire for example), electrons are forced to move in a direction perpendicular to the direction of the magnetic field. This results in generating a pressure of electrons in the conductor (electromotive force), which results in a flow of electrons in one direction. To be more technical, a time rate of change in magnetic flux across a conductor induces an electromotive force in a conductor and its direction is given by Fleming’s right hand rule. This phenomenon is used largely to produce electricity.

To achieve this change in magnetic flux across a conducting wire, magnets and the conducting wires are moved relatively, such that flux varies based on the position. By increasing the number of wires, you can increase the resulting electromotive force; therefore, wires are wound into a coil, containing a large number of turnings. Setting either the magnetic field or the coil in rotational motion, while the other is stationary, allows continuous flux variation.

The rotating part of the generator is called a Rotor, and the stationary part is called a stator. The emf generating part of the generator is referred to as the Armature, while the magnetic field is simply known as Field. Armature can be used as either the stator or the rotor while the field component is the other. Increasing the field strength also allows increasing the induced emf.

Since permanent magnets cannot provide the intensity needed to optimize the power production from the generator, electromagnets are used. A lower current is flowing through this field circuit than the armature circuit and lower current pass through the slip rings, which keep the electrical connectivity in the rotor. As a result, most of the AC generators have the field winding on the rotor and the stator as the armature winding.

More about the Electric Motor

BC07 Blue Chip Differences Between Electric Motors and Generators

The principle used in motors is another aspect of the principle of induction. The law states if a charge is moving in a magnetic field, a force acts on the charge in a direction perpendicular to both the velocity of the charge and the magnetic field. The same principle applies for a flow of charge, is a current and the conductor carrying the current. The direction of this force is given by Fleming’s right hand rule. The simple result of this phenomenon is that if a current flows in a conductor in a magnetic field the conductor moves. All the induction motors are working on this principle.

As like the generator, the motor also has a rotor and a stator where a shaft attached to the rotor delivers the mechanical energy. The number of turnings of the coils and the strength of the magnetic field affects the system in the same way.

A quick summary:

What is the difference between Electric Motor and Electric Generator?

  • Generator converts mechanical energy to electrical energy, while motor converts mechanical energy to electrical energy.
  • In a generator, shaft attached to the rotor is driven by a mechanical force and electric current is produced in the armature windings, while the shaft of a motor is driven by the magnetic forces developed between the armature and field; current has to be supplied to the armature winding.
  • Motors (generally a moving charge in a magnetic field) obey the Fleming`s left hand rule, while the generator obeys Fleming’s left hand rule.

Tomorrow, the Difference Between Impedance and Resistance


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