Fault Finding; Frequency Converter - Grundfos CRK Installations- Und Bedienungsanleitung

12. Fault finding

Warning
Before starting work on the pump, make
sure that all power supplies to the pump
have been switched off and that they
cannot be accidentally switched on.
Fault
1. Motor does not run
when started.
2. Motor-protective
circuit breaker trips
out immediately
when power supply
is switched on.
3. Motor-protective-
circuit breaker trips
out occasionally.
4. Motor-protective-
circuit breaker has
not tripped out but
the pump does not
run.
5. Pump runs but
gives no liquid or
pump performance
is not constant.
6. Leakage in shaft
seal.
7. Noise.
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Cause
a) Power supply failure.
b) Fuses are blown.
c) Motor-protective circuit breaker has
tripped out.
d) Thermal protection has tripped out.
e) Main contacts in motor-protective
circuit breaker are not making contact
or the coil is faulty.
f) Control circuit is defective.
g) Motor is defective.
a) One fuse blown/automatic circuit
breaker has tripped out.
b) Contacts in motor-protective circuit
breaker are faulty.
c) Cable connection is loose or faulty.
d) Motor winding is defective.
e) Pump mechanically blocked.
f) Motor-protective circuit breaker
overload setting is too low.
a) Motor-protective circuit breaker
overload setting is too low.
b) Low voltage at peak times.
a) Check 1 a), b), d), e) and f).
a) Pump strainer partly blocked by
impurities.
b) Liquid level in tank too low.
c) Pump draws in air.
a) Shaft seal is defective.
a) Cavitation.
b) Pump does not rotate freely (frictional
resistance) because of incorrect
pump shaft position.
c) Frequency converter operation.
Remedy
Connect the power supply.
Replace fuses.
Reactivate the motor-protective
circuit breaker.
Reactivate the thermal protection.
Replace contacts or magnetic coil.
Repair the control circuit.
Replace the motor.
Replace fuse/cut in the circuit
breaker.
Replace motor-protective circuit
breaker contacts.
Fasten or replace the cable
connection.
Replace the motor.
Remove the mechanical blocking of
the pump.
Set the motor-protective circuit
breaker correctly.
Set the motor-protective circuit
breaker correctly.
Reestablish constant power supply.
Clean the strainer.
Increase the liquid level.
Check the suction conditions.
Replace the shaft seal.
Check the suction conditions.
Adjust the pump shaft.
See section

7.1 Frequency converter

operation.