Insulation Resistance Test Standard For Motor

B kv is the rated machine terminal to terminal voltage.

Insulation resistance test standard for motor.

1k v 1 mω minimum 1kv 1 mω 1kv. 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. Ground insulation test of a motor. For a 440v motor minimum ir between phase and ground 440 1000 1 1 44 megohm example 2.

Curve a shows test values as measured. 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. Values based on ieee std 43 2013. Set the voltage.

As per ie rules 1956. Curve b shows same values corrected to 20 c see page 22 giving a definite downward trend toward an unsafe condition. Figure 4 typical record of insulation resistance of a mill motor. Reverse side of card at right is used to record the test data.

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. Dc voltage of 500 or 1000 v is applied between the windings and the ground of the motor. The measurement of insulation resistance is carried out by means of a megohmmeter high resistance range ohmmeter this is how the test works. 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.

The international electrical testing association neta specification maintenance testing specifications for electrical power distribution equipment and. Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv. One meg ohm rule for ir value for equipment. Z 5 date of test r eading in megohms the graph below shows an example of the insulation resistance readings on an electric motor.

Since 80 of electrical maintenance and testing. Minimum ir in megohm kv 1 example 1. Figure 3 typical scale on the megger insulation tester. Minimum insulation resistance ir value is depend upon rated line voltage of equipment.

Ansi neta mts 2015 table 100 11 insulation resistance test values rotating machinery for one minute at 40 c. Also acceptable values of insulation resistance depend upon the equipment you re testing. During the measurement and immediately afterwards some of the terminals carry dangerous voltages and must not be touched. For 11kv equipment mi.

Based upon equipment rating. Insulation resistance test insulation resistance failure of an electric motor is one of the first signs that the motor is about to fail.