7 Servicing/Maintenance
41 of 72
Amarex N
7.2.1.3 Measuring the insulation resistance
Measure the insulation resistance of the motor winding during annual maintenance
work.
ü
The pump set has been disconnected in the control cabinet.
ü
Use an insulation resistance measuring device.
ü
The recommended measuring voltage equals 500 V (maximum permissible
1000 V).
1.
Measure the winding to chassis ground.
To do so, connect all winding ends together.
2.
Measure the winding temperature sensors to chassis ground.
To do so, connect all core ends of the winding temperature sensors together
and connect all winding ends to chassis ground.
ð
The insulation resistance of the core ends to chassis ground must not be lower
than 1 MΩ.
If the resistance measured is lower, power cable and motor resistance must be
measured separately. Disconnect the power cable from the motor for this
purpose.
NOTE
If the insulation resistance of the power cable is lower than 1 MΩ, the power cable
is defective and must be replaced.
NOTE
If the insulation resistances measured on the motor are too low, the winding
insulation is defective. The pump set must not be returned to service in this case.
7.2.1.4 Checking the sensors
CAUTION
Excessive test voltage
Damage to the sensors!
▷
Never test the sensors with voltages exceeding 30 V.
The tests described below measure the resistance at the core ends of the control
cable. The actual sensor function is not tested.
Bimetal switches in the
motor
Table 16:
Resistance measurement of bimetal switch in the motor
Measurement between terminals ...
Resistance
20 and 21 and between 21 and 22
< 1 Ω
If the specified tolerances are exceeded, disconnect the power cable at the pump set
and repeat the check inside the motor.
If the tolerances are exceeded here, too, the motor section has to be opened and
overhauled. The temperature sensors are fitted in the stator winding and cannot be
replaced.
Leakage sensor in the
motor
Table 17:
Resistance measurement of the leakage sensor in the motor
Measurement between terminals ...
Resistance
9 and earth conductor (PE)
> 1 Ω
Lower resistance values suggest water ingress into the motor. In this case the motor
must be opened and overhauled.
Summary of Contents for Amarex N
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