Fault Finding - Grundfos S2 Série Mode D'emploi

11. Fault finding

Before attempting to diagnose any fault, read and observe the safety instructions in section Safety instructions and requirements.
Fault Cause
No power supply.
The pump does not start or
Moisture in the stator housing or in the terminal box.
it stops without visible
The moisture switch interrupts the supply voltage.
cause.
The WIO sensor is not covered by oil. The sensor
interrupts the supply voltage.
Missing phase.
The pump is overloaded.
The pump does not start or
it stops. The control panel
of the controller indicates
that the motor-protective
circuit breaker or
The impeller is jammed by impurities.
protection equipment is
tripped out.
The motor-protective circuit breaker is set incorrectly.
The thermal switches are tripped out. Insufficient motor
cooling.
The moisture switch in the motor is tripped out.
A power cable is defective.
Fluctuating voltage.
Wrong direction of rotation.
The impeller is worn.
The impeller is loose.
The pump or the pipes are clogged by impurities.
The pump head is too high.
The pump runs, but does
not deliver the rated flow.
The valves are closed or blocked.
The non-return valve is not operating.
There is air in the pump or the inlet pipe.
The pumped liquid is too dense.
The pump is not properly connected to the auto
coupling.
There is leakage in the pipes.
A clogged pump causes the motor-protective circuit
breaker to trip out.
The pump starts, but stops
An overheated motor causes the thermal switches to
immediately.
trip out.
The level switch is out of adjustment or defective.
Remedy
Re-establish the power supply, start the pump manually
and check contactor operation.
Contact an authorized service workshop.
Contact an authorized service workshop.
Re-establish all phases.
Let the pump cool down for approximately 10 minutes
and try to start again. In case the pump starts now, the
first stop was caused by a tripping thermal switch.
If the fault occurs again, find the cause of the overload.
Check the control panel fuses and switch them on in
case they are tripped. Wait for approximately 10
minutes until the pump is cooled down, and try to start
the pump again. In case the pump does not start, the
overload relay is tripped and the pump needs service.
Contact an authorized service workshop.
Clean the impeller as required.
Set the motor-protective circuit breaker as required in
relation to the rated current.
Re-establish motor cooling.
Contact an authorized service workshop.
Contact an authorized service workshop.
Re-establish correct voltage supply. Permissible
deviation is ± 10 %.
Interchange two phases in the power supply to the
motor.
Adjust the impeller clearance.
If the impeller must be replaced, contact an authorized
service workshop.
Contact an authorized service workshop.
Clean the pump or the pipes as required.
Measure the differential pressure and compare the
value with the pump curve. Remove the blockage in the
outlet pipe.
Open, clean or replace the valves as required.
Vent the pump or the inlet pipe. Set a higher stop level
in the pit.
Dilute the pumped liquid.
Pump down the liquid level in pit. Lift out the pump and
relocate the pump on the auto coupling.
Repair or replace the pipes.
Clean the pump.
Allow the pump to cool. Clean the pump.
Clean or reset the level switch or replace as required.
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