Testing Of DC Machine | Electrical Machine Theory

Testing Of DC Machine | Electrical Machine Theory

Testing Of DC Machine |  Electrical Machine Theory


Testing Of DC Machine is first and foremost section after it manufacturers, So testing Of Dc Machine is necessary to learn for all electrical engineer who is more interested in Electrical Machine. 

Testing Of DC Machine |  Electrical Machine Theory 


For testing Of DC Machine various tests are required which all are described below


Testing Of DC Machine


The following important performance tests are conducted on D.C.machines:

1.The magnetisation or open circuit test

2.The load characteristics

3.The determination of efficiency curve

4.The temperature rise test.


The method for determining efficiency can be divided into following three methods:


(1)Direct method

The direct tests can be used only on small machines.


If brake is to be applied to a series motor,the brake must be tight before the motor is
started,otherwise the armature may get damaged and fly to pieces.

(2)Indirect method

The simplest of the indirect tests is Swinburne test.This method may be applied to series motors,because the speed of a series motor being very high at no-load.


it is not possible to run a series motor on no-load.


(3) Regenerative method

Hopkinson's test or Back to back test, It is a regenerative test.


The power taken from the supply is that required to overcome the losses only.


(4) Retardation test

This method is applicable to shunt motors and generators and is used for finding the stray losses.


(5) Field's test

This test is applicable to two similar series motors.