Insulation Resistance Test Standard For Motor

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

Insulation resistance test standard for motor.

Since 80 of electrical maintenance and testing. Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv. B kv is the rated machine terminal to terminal voltage. Also acceptable values of insulation resistance depend upon the equipment you re testing.

At a pressure of 1000 v applied between each live conductor and earth for a period of one minute the insulation resistance of hv installations shall be at least 1 mega ohm or as specified by the bureau of indian standards. At a the insulation resistance decreases due to aging and dust accumulation. Values based on ieee std 43 2013. Z 5 date of test r eading in megohms the graph below shows an example of the insulation resistance readings on an electric motor.

Curve a shows test values as measured. For 11kv equipment mi. Set the voltage. Figure 3 typical scale on the megger insulation tester.

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. One meg ohm rule for ir value for equipment. During the measurement and immediately afterwards some of the terminals carry dangerous voltages and must not be touched. 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.

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. 1k v 1 mω minimum 1kv 1 mω 1kv. Minimum ir in megohm kv 1 example 1. Curve b shows same values corrected to 20 c see page 22 giving a definite downward trend toward an unsafe condition.

Reverse side of card at right is used to record the test data. As per ie rules 1956. 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.

Based upon equipment rating. 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. Figure 4 typical record of insulation resistance of a mill motor. 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. For a 440v motor minimum ir between phase and ground 440 1000 1 1 44 megohm example 2.