
B-65222EN/03 MAINTENANCE 2.CHECKING ELECTRIC CHARACTERISTICS
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2.1 CHECKING INSULATION RESISTANCE
Measure an insulation resistance between each winding and motor
frame using an insulation resistance meter (500 VDC). Judge the
measurements according to the following table.
Insulation resistance Judgment
100 MΩ or higher Acceptable
10 to 100 MΩ
The winding has begun deteriorating. There is no
problem with the performance at present. Be sure
to perform periodic inspection.
1 to 10 MΩ
The winding has considerably deteriorated.
Special care is in need. Be sure to perform
periodic inspection.
Lower than 1 MΩ Unacceptable. Replace the motor.
CAUTION
If a voltage is kept applied to the motor at the time of
insulation resistance measurement, the insulation of
the motor can degrade. Make an insulation
resistance measurement in a shortest possible time.