English (GB)
16
12. Fault finding
13. Disposing of the product
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.
Subject to alterations.
Warning
Before removing the terminal box cover and before
removing or dismantling the pump, make sure that
the power supply has been switched off and that it
cannot be accidentally switched on.
Fault Cause Remedy
1. Motor does not run
when started.
a) Supply failure. Connect the power supply.
b) The fuses are blown. Replace fuses.
c) The motor-protective circuit breaker has tripped. Reactivate the motor-protective circuit breaker.
d) The thermal protection has tripped. Reactivate the thermal protection.
e) The main contacts in the motor-protective circuit
breaker are not making contact or the coil is
faulty.
Replace contacts or magnetic coil.
f) The control circuit is defective. Repair the control circuit.
g) The motor is defective. Replace the motor.
2. Motor-protective circuit
breaker trips
immediately when
power supply is
switched on.
a) One fuse is blown or the automatic circuit
breaker is tripped.
Replace the fuse or cut in the circuit breaker.
b) The contacts in the motor-protective circuit
breaker are faulty.
Replace motor-protective circuit breaker contacts.
c) The cable connection is loose or faulty. Fasten or replace the cable connection.
d) The motor winding is defective. Replace the motor.
e) The pump is mechanically blocked. Remove the mechanical blocking of the pump.
f) The motor-protective circuit breaker setting is
too low.
Set the motor-protective circuit breaker correctly.
3. Motor-protective circuit
breaker trips
occasionally.
a) The motor-protective circuit breaker setting is
too low.
Set the motor-protective circuit breaker correctly.
b) Low voltage at peak times. Check the power supply.
4. Motor-protective circuit
breaker has not tripped
but the pump does not
run.
a) Check 1 a), b), d), e) and f).
5. Pump performance not
constant.
a) The pump inlet pressure is too low (cavitation). Check the inlet conditions.
b) The inlet pipe or pump is partly blocked by
impurities.
Clean the inlet pipe or pump.
c) The pump draws in air. Check the inlet conditions.
6. Pump runs but gives no
water.
a) The inlet pipe or pump is blocked by impurities. Clean the inlet pipe or pump.
b) The foot or non-return valve is blocked in closed
position.
Repair the foot or non-return valve.
c) There is a leakage in the inlet pipe. Repair the inlet pipe.
d) There is air in the inlet pipe or pump. Check the inlet conditions.
e) The motor runs in the wrong direction of
rotation.
Change the direction of rotation of the motor.
7. Pump runs backwards
when switched off.
a) There is a leakage in the inlet pipe. Repair the inlet pipe.
b) The foot or non-return valve is defective. Repair the foot or non-return valve.
8. Leakage in shaft seal. a) The shaft seal is defective. Replace the shaft seal.
9. Noise. a) Cavitation. Check the inlet conditions.
b) The pump does not rotate freely due to frictional
resistance, as a result of incorrect pump shaft
position.
Adjust the pump shaft.
Follow the procedure in fig. F, G or H at the end of
these instructions.
c) Frequency converter operation. See section 7.5 Frequency converter operation.
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