Figure 3 typical scale on the megger insulation tester.
Motor insulation resistance test procedure.
Curve a shows test values as measured.
Reverse side of card at right is used to record the test data.
For a three phase motor insulation resistance is usually measured between each motor winding or phase and between each motor phase and motor frame earth using an insulation tester or megger.
In an industrial facility the recommended procedure is to perform periodic tests and record the results so that damaging trends can be detected and corrected to prevent an outage.
A if the insulation resistance of a new cleaned or repaired motor that has been stored for some time is less then 10 mω the reason might be that the windings are humid and.
Since 80 of electrical maintenance and testing.
The measurement of insulation resistance is carried out by means of a megohmmeter high resistance range ohmmeter this is how the test works.
At a the insulation resistance decreases due to aging and dust accumulation.
The insulation resistance test consists in measuring the insulation resistance of a.
Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv.
Ground insulation test of a motor.
During the measurement and immediately afterwards some of the terminals carry dangerous voltages and must not be touched.
Dc voltage of 500 or 1000 v is applied between the windings and the ground of the motor.
The insulation resistance test is the second test required by the electrical safety testing standards.
Regular checks of motor insulation resistance the key to prolonging the life of any electrical device is periodic checks maintenance the insulation resistance of stored and active motors should be checked regularly.
For a three phase motor the isolation resistance can usually be measured between each motor winding or phase and between each motor stage and motor frame earth by an insulation tester or megger 4.
The insulation resistance tester generally known by its trade name megger is capable of providing critical information regarding the condition of motor insulation.
Also acceptable values of insulation resistance depend upon the equipment you re testing.
Insulation resistance test insulation resistance failure of an electric motor is one of the first signs that the motor is about to fail.
Loss of insulation resistance of an electric motor is one of the first signs of motor failure.
Figure 4 typical record of insulation resistance of a mill motor.
Hands down without a doubt one of the most universally searched topics on ec m s website from a historical perspective is insulation resistance testing as a result some of our most popular evergreen articles like understanding insulation resistance testing continue to top the charts when it comes to most popular content.
Curve b shows same values corrected to 20 c see page 22 giving a definite downward trend toward an unsafe condition.
Set the voltage.
