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Difference between DC Motor and DC Generator

DC motor and DC generator are similar from the mechanical perspective, however from a technical stand point, both differ from each other significantly. The most significant difference between DC motor and DC generator lies in the conversion mechanism. DC motor converts electrical energy into mechanical energy whereas DC generator converts mechanical energy into an electrical energy. Furthermore, in DC motors, EMF in the armature is less than its terminal voltage (${{E}_{b}}<V$) whereas in DC generators, generated EMF is more than its terminal voltage (${{E}_{g}}>V$).

Difference between DC Motor and DC Generator

CharacteristicsDC MotorDC Generator
Input/outputMotor has a DC Current as an input and provides mechanical outputGenerator has a mechanical energy as an input and provides DC Current as an output
CommutationMotor uses commutators for changing the magnetic field polarityGenerator uses the commutators in order to cancel the polarization effect
Electromotive force (EMF)Emf is utilized by coil and useful for rotating the axleEMF, produced around the coil, is transmitted to the load and used by them
EMF Vs Terminal VoltageEMF in armature is less than its terminal voltage (${{E}_{b}} < V$)Produced EMF is more than its terminal voltage (${{E}_{g}}>V$)
Generated EMF/Back EMFFor DC motor, back EMF is:
${{E}_{b}}=V-{{I}_{a}}{{R}_{a}}$
Whereas V is the terminal voltage, I a is the armature current, and R a is the armature resistance
For DC Generator, generated EMF is:
${{E}_{g}}=V+{{I}_{a}}{{R}_{a}}$
Whereas V is the terminal voltage, I a is the armature current, and R a is the armature resistance
Rule of hand (Working Principle)It’s working principle is based on Fleming Left-hand ruleIt’s working principle is based on Fleming Right-hand rule
OperationIf apply more power, it rotates its shaft faster which is contingent upon motor’s ratingIt produces fixed voltage at a rated rpm (revolution per minute)
TypesShunt and compound woundShunt, compound, and series wound

 

 

About Ahmad Faizan

Mr. Ahmed Faizan Sheikh, M.Sc. (USA), Research Fellow (USA), a member of IEEE & CIGRE, is a Fulbright Alumnus and earned his Master’s Degree in Electrical and Power Engineering from Kansas State University, USA.

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