Fault Finding; Warning; Disposal; Frequency Converter - Grundfos CRT Serie Montage- Und Betriebsanleitung

12. Fault finding

Warning

Before removing the terminal box cover and before
removing/dismantling the pump, make sure that the
power supply has been switched off and that it
cannot be accidentally switched on.
Fault
1. Motor does not run when
started.
2. Motor-protective circuit breaker
trips immediately when power
supply is switched on.
3. Motor-protective circuit breaker
trips occasionally.
4. Motor-protective circuit breaker
has not tripped but the pump
does not run.
5. Pump performance not
constant.
6. Pump runs but gives no water.
7. Pump runs backwards when
switched off.
8. Leakage in shaft seal.
9. Noise.

13. Disposal

This product or parts of it must be disposed of in an
environmentally sound way:
1. Use the public or private waste collection service.
2. If this is not possible, contact the nearest Grundfos company
or service workshop.
Cause
a) Supply failure.
b) Fuses are blown.
c) Motor-protective circuit breaker has tripped.
d) Thermal protection has tripped.
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/automatic circuit breaker is blown. Replace the fuse/cut in the circuit breaker.
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 setting is too
low.
a) Motor-protective circuit breaker setting is too
low.
b) Low voltage at peak times.
a) Check 1 a), b), d), e) and f).
a) Pump inlet pressure is too low (cavitation).
b) Suction pipe/pump partly blocked by
impurities.
c) Pump draws in air.
a) Suction pipe/pump blocked by impurities.
b) Foot or non-return valve blocked in closed
position.
c) Leakage in suction pipe.
d) Air in suction pipe or pump.
e) Motor runs in the wrong direction of rotation. Change the direction of rotation of the motor.
a) Leakage in suction pipe.
b) Foot or non-return valve defective.
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 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.
Check the power supply.
Check the suction conditions.
Clean the suction pipe/pump.
Check the suction conditions.
Clean the suction pipe/pump.
Repair the foot or non-return valve.
Repair the suction pipe.
Check the suction conditions.
Repair the suction pipe.
Repair the foot or non-return valve.
Replace the shaft seal.
Check the suction conditions.
Adjust the pump shaft.
See section

7.5 Frequency converter

operation.
13