Amarex KRT series, Installation And Operating Manual, Page: 57 / 124

7 Servicing/Maintenance
57 of 124
Amarex KRT
DANGER
Defective ground conductor
Electric shock!
▷
Never switch on a pump set with a defective ground conductor.
7.2.1.4 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 maximum measuring voltage is 500 V (maximum permissible voltage 1000 V).
1. Measure the winding to chassis ground.
To do so, connect all winding ends together.
2. Measure the winding temperature sensor 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.
7.2.1.5 Checking the sensors
CAUTION
Excessive test voltage
Damage to the sensors!
▷ Use a commercially available ohmmeter to measure the resistance.
The tests described below measure the resistance at the core ends of the control
cable. The actual sensor function is not tested.
Temperature sensors in the
motor winding
Table 27: Resistance measurement
Measurement between terminals ... Resistance
[Ω]
21 and 22
14)
< 1
10 and 11 200 to 1000
31 and 32
15)
100 to 120
33 and 34
15)
100 to 120
35 and 36
15)
100 to 120
14) Only for pump sets without cooling system, installation type S
15) Optional