Fault
Cause
Remedy
The impeller is loose.
Contact an authorised service work-
shop.
The pump or the pipes are clogged
by impurities.
Clean the pump or the pipes as re-
quired.
The pump is head too high.
Measure the differential pressure
and compare the value with the
pump curve. Remove the blockage
in the outlet pipe.
The valves are closed or blocked.
The non-return valve is not operat-
ing.
Open, clean or replace the valves
as required.
There is air in the pump or the inlet
pipe.
Vent the pump or the inlet pipe. Set
a higher stop level in the pit.
The pumped liquid is too dense.
Dilute the pumped liquid.
The pump is not properly connected
to the auto coupling.
Pump down the liquid level in the
pit. Lift out the pump and relocate it
on the auto coupling.
There is leakage in the pipes.
Repair or replace the pipes.
The pump starts but stops immedi-
ately.
A clogged pump causes the motor-
protective circuit breaker to trip out.
Clean the pump.
An overheated motor causes the
thermal switches to trip out.
Let the pump cool. Clean the pump.
The level switch is out of adjust-
ment or defective.
Clean or reset the level switch or
replace it as required.
The pump is vibrating or emitting
excessive noise.
The pump is partly clogged by im-
purities.
Clean the pump.
Wrong direction of rotation.
Interchange two phases in the pow-
er supply to the motor.
The pump is operating outside the
specified operating range.
Re-establish proper operating con-
ditions.
The pump is defective.
Repair the pump or contact an au-
thorised service workshop, if neces-
sary.
The pump is improperly connected
to the auto coupling.
Pump down the liquid level in the
pit. Lift out the pump and relocate it
on the auto coupling.
The pump is cavitating.
Clean the inlet pipe.
The base stand, the auto coupling,
the ring stand or the guide rails are
installed incorrectly.
Install the components correctly.
The oil is watery or emulsified.
The lower mechanical shaft seal is
leaking.
Contact an authorised service work-
shop.
Low oil level.
The upper mechanical shaft seal is
leaking.
Contact an authorised service work-
shop.
39
English (GB)
Summary of Contents for ST-55-520
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