Insulation Resistance Test Standard For Motor

For 11kv equipment mi.

Insulation resistance test standard for motor.

Figure 3 typical scale on the megger insulation tester. Values based on ieee std 43 2013. 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. Based upon equipment rating.

Curve a shows test values as measured. Also acceptable values of insulation resistance depend upon the equipment you re testing. 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. 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.

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. B kv is the rated machine terminal to terminal voltage. Curve b shows same values corrected to 20 c see page 22 giving a definite downward trend toward an unsafe condition. During the measurement and immediately afterwards some of the terminals carry dangerous voltages and must not be touched.

The measurement of insulation resistance is carried out by means of a megohmmeter high resistance range ohmmeter this is how the test works. 1k v 1 mω minimum 1kv 1 mω 1kv. At a the insulation resistance decreases due to aging and dust accumulation. Figure 4 typical record of insulation resistance of a mill motor.

Set the voltage. As per ie rules 1956. The international electrical testing association neta specification maintenance testing specifications for electrical power distribution equipment and. Minimum insulation resistance ir value is depend upon rated line voltage of equipment.

Insulation resistance test insulation resistance failure of an electric motor is one of the first signs that the motor is about to fail. A rated line to line voltage for three phase ac machines line to ground voltage for single phase machines and rated direct voltage for dc machines or field windings. Dc voltage of 500 or 1000 v is applied between the windings and the ground of the motor. Since 80 of electrical maintenance and testing.

Reverse side of card at right is used to record the test data. Z 5 date of test r eading in megohms the graph below shows an example of the insulation resistance readings on an electric motor. Minimum ir in megohm kv 1 example 1. Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv.

Ground insulation test of a motor. One meg ohm rule for ir value for equipment.