Electrical machine
 | This article may require copy editing for grammar, style, cohesion, tone, or spelling. (October 2009) |
An Electrical machine is a device that converts mechanical energy to electrical energy or vice versa, and changes AC voltage from one level to another level.
Electrical machines are divided into three parts:
Generator
A generator is the device that converts mechanical energy at its prime mover to produce constant electrical energy at its output. In more technical words it is a dynamic electrical energy machine. Generator is classified into two types: AC generator and DC generator.
The basic requirements for a dynamically induced emf to exist are the following: (1) A steady magnetic field (2) A conductor capable of carrying current (3) The conductor to move in the magnetic field
AC Generator
AC generator is the generator that converts mechanical energy at its prime mover into AC electricity.
AC generator is classified into several types:
- Asynchronous AC generator or induction AC generator, an AC generator whose field current is supplied by magnetic induction into the field windings.
- Synchronous AC generator, an AC generator whose magnetic field current is provided by a separate DC current source, either external DC source or mounted DC source.
there is no induction generator
DC Generator
DC generator is the generator that produces DC power i.e.,constant power P=V*Iby taking mechanicalenergy as input. Example of a DC generator is dynamo.
Motor
Motor is the device that converts electrical energy at its input to produce mechanical energy. Motor is classified into two types: AC motor and DC motor.
AC Motor
AC motor is the motor that converts AC electrical energy at its input into mechanical energy.
AC motor is classified into several types:
DC Motor
DC motor is the motor that converts DC electricity into mechanical energy. Its main components are stator, rotor, windings (field windings and armature windings) and commutator.
DC motor is classified into five types:
- Compounded DC motor
- Permanent magnet DC motor
- Separately excited DC motor, a DC motor whose field circuit receives power from a separate constant voltage supply.
- Series DC motor, a DC motor whose field windings consist of relatively few turns and connected in series with the armature circuit.
- Shunt DC motor, a DC motor whose field circuit receives power directly across the armature terminals.
Losses in DC motor are brush drop losses, core losses, mechanical losses and stray losses.
Transformer
Transformer is the device that converts AC voltage from one level to another level higher or lower, or even to the same level without changing the frequency. It works based on the principle of mutual induction, so its power remains approximately constant, where as frequency also remains the same.
References
Chapman, Stephen J. 2005. Electrical Machinery Fundamentals. 4th Ed. New York: McGraw Hill.