Figure 4 typical record of insulation resistance of a mill motor.
Insulation resistance test 3 phase motor pdf.
Curve b shows same values corrected to 20 c see page 22 giving a definite downward trend toward an unsafe condition.
Curve a shows test values as measured.
It is used to convert electrical energy into mechanical energy.
The insulation resistance tester or megohmmeter generally known by its trade name megger can provide critical information regarding the condition of motor insulation.
Introduction the induction motor is one of the most important motors used in industrial applications.
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.
Insulation resistance test insulation resistance failure of an electric motor is one of the first signs that the motor is about to fail.
Unlike an ohmmeter a megger can measure high voltage resistance values which are generally the kinds of values you will encounter with three phase motors.
Figure 3 typical scale on the megger insulation tester.
During the measurement and immediately afterwards some of the terminals carry dangerous voltages and must not be touched.
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.
Dc voltage of 500 or 1000 v is applied between the windings and the ground of the motor.
To measure the resistance in a three phase motor you will need a megohmmeter otherwise known as a megger.
Three phase dual voltage motor insulation resistance testing three phase dual voltage motors are used for most day to day operations in today s industrial plants.
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 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.
These motors run conveyor belts pumps fans and many other applications.
Ground insulation test of a motor.
The measurement of insulation resistance is carried out by means of a megohmmeter high resistance range ohmmeter this is how the test works.
In an industrial facility the recommended procedure is to perform periodic tests and record the results so damaging trends can be detected and corrected to prevent an outage.
In this video you will find out how to test 3 phase induction motor.
The primary causes of insulation.
Reverse side of card at right is used to record the test data.
Loss of insulation resistance of an electric motor is one of the first signs of motor failure.
For tests we ll use megger mit 310.
