Teco Installation and Maintenance Manual
TEFC Squirrel Cage Induction Motors
Teco Electric and Machinery Company
Manual Number: IOM ~ TEFC Rev.01
18
be electrical as opposed to fuelled (such as kerosene) where a malfunction of
the fuel burner could result in carbon deposits entering the motor.
iv. Insulation resistance measurements can be made while the winding is being
heated. However, they must be corrected to 40
0
C for evaluation since the
actual insulation resistance will decrease with increasing temperature. As an
approximation for a new winding, the insulation resistance will approximately
halve for each 10
0
C increase in insulation temperature above the dew point
temperature.
d. Should the resistance fail to attain the specified value even after drying,
careful examination should be undertaken to eliminate all other possible
causes, if any.
4.1.3.
Power Supply
a.
Is the capacity of the power supply adequate?
b.
Do voltage and frequency of supply match with those on the nameplate?
c.
Voltage variation should be confined to /-10% of the rated value
and the phase to phase voltages should be balanced.
Caution must be exercised, when heating the motor with any source
of heat other than self-contained space heaters, to raise the
winding temperature at a gradual rate to allow any entrapped
moisture to vaporise and escape without rupturing the insulation.
The entire heating cycle should extend over 15-20 hours.
Ensure adequate guarding is provided so live parts cannot be touched
.
