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7. Fault finding
Before removing the terminal box cover and before any dismantling of the pump, make sure that the electricity supply
has been switched off. It must be ensured that it cannot be accidentally switched on.
Fault
Cause
Remedy
1.
Motor does not run when
started.
a) Electrical supply failure.
Switch on the electricity supply.
b) Fuses are blown.
Replace the fuses.
c) Motor-protective circuit breaker has
tripped out.
Reactivate the motor-protective circuit
breaker.
d) Contacts of the motor-protective circuit
breaker or magnet coil defective.
Replace the contacts or magnetic coil.
e) Impeller blocked. Motor cannot rotate.
Clean the inside of the pump and inspect for
damage.
f)
Control-current circuit defective.
Repair the control-current circuit.
g) Motor defective.
Replace the motor.
2.
The motor-protective cir-
cuit breaker trips out im-
mediately when
reactivated.
a) Fuse is blown.
Replace the fuse.
b) Contacts of motor-protective circuit
breaker defective.
Replace the contacts.
c) Cable connection is loose or faulty.
Fasten or replace the cable.
d) Motor winding is defective.
Replace the motor.
e) The pump is mechanically blocked.
Clear obstruction.
f)
The overload setting of motor-protective
circuit breaker is too low.
Set the motor-protective circuit breaker cor-
rectly.
3.
The motor-protective cir-
cuit breaker trips out oc-
casionally.
a) The overload setting of motor-protective
circuit breaker is too low.
Set the motor-protective circuit breaker cor-
rectly.
b) Supply voltage periodically too low or too
high.
Check the voltage supply.
c) Differential pressure across pump too low. Vent the pump. See section
4.
Motor-protective circuit
breaker has not tripped
out but the pump does
not run.
a) Check 1 a), b), d) and e).
5.
The pump capacity is un-
stable.
a) Pump inlet pressure too low.
Increase the inlet pressure.
b) Suction pipe/pump partly clogged by impu-
rities.
Clean the suction pipe/pump.
c) The pump draws in air.
- Leakage in pipe.
- Water level in tank too low.
- Repair the leakage.
- Increase the water level in the tank.
Vent the system.
6.
Pump runs but gives no
liquid.
a) Suction pipe/pump clogged by impurities.
Clean the suction pipe/pump.
b) The foot or non-return valve is stuck in its
closed position.
Clean/repair the foot or non-return valve.
c) Leakage in suction pipe.
Repair the leakage.
d) Air in suction pipe or pump.
Vent the pump.
e) Motor rotates in the wrong direction.
Change the direction of rotation.
7.
The pump runs back-
wards when switched off.
a) Leakage in suction pipe.
Repair the leakage.
b) Foot or non-return valve defective.
Replace the defective foot or non-return valve.
c) The foot or non-return valve is stuck in its
closed position.
Clean/repair the foot or non-return valve.
8.
Leakage in shaft seal.
a) Adjustment of pump shaft in coupling is in-
correct.
Adjust the shaft and check the shaft seal.
b) Shaft seal is defective.
Replace the shaft seal.
