At a the insulation resistance decreases due to aging and dust accumulation.
Motor insulation resistance test iec standard.
The graph below shows an example of the insulation resistance readings on an electric motor.
Figure 3 typical scale on the megger insulation tester.
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.
During the measurement and immediately afterwards some of the terminals carry dangerous voltages and must not be touched.
The results obtained from ir test are not intended.
Testing and inspection environmental measurements laboratory instrumentation power and energy.
Power cables with extruded insulation and their accessories for rated voltages from 1 kv um 1 2 kv up to 30 kv um 36 kv part 1.
The measurement of insulation resistance is carried out by means of a megohmmeter high resistance range ohmmeter this is how the test works.
As a production test this test is often used as a customer acceptance test with minimum insulation resistance per unit length often specified by the customer.
Based upon equipment rating.
Dc voltage of 500 or 1000 v is applied between the windings and the ground of the motor.
Ground insulation test of a motor.
Reverse side of card at right is used to record the test data.
The intent of the iec standard is to specify test methods that assure a given stator insulation design can prevent formation of pd in new windings and continue to suppress pd throughout the life of the motor type i insulation.
Curve b shows same values corrected to 20 c see page 22 giving a definite downward trend toward an unsafe condition.
See the site fixed equipment for measurement and testing of electrical networks energy management and optimization systems.
1 magnet wire at high stress in air voids b.
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.
Cables for rated voltages of 1 kv um 1 2 kv and 3 kv um 3 6 kv reference number iec 60502 1 2004 e international standard iec 60502 1 second edition 2004 04.
Portable measurement equipment in a wide variety of fields.
At c the fault has been repaired rewinding of the motor so the insulation resistance has returned to.
The measurement of insulation resistance is a common routine test performed on all types of electrical wires and cables.
Curve a shows test values as measured.
As per ie rules 1956.
Figure 4 typical record of insulation resistance of a mill motor.
Iec 60034 27 4 2018 provides recommended test procedures for the measurement of insulation resistance and polarization index of stator and rotor winding insulation of rotating electrical machines.
The sharp fall at b indicates there was an insulation fault.
