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11. Fault finding
12. 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.
Subject to alterations.
Warning
Before attempting to diagnose any fault, make sure that the fuses have been removed or the mains switch has been
switched off. Make sure that the power supply cannot be accidentally switched on. All rotating parts must have
stopped moving.
Read and observe the safety instructions in section 6. Safety.
Fault Cause Remedy
1. Pump does not start or
stops without visible
cause.
a) No power supply. Re-establish power supply. Start the pump
manually and check contactor operation.
2. Pump does not start or
stops. The control panel
of the controller indicates
that the motor protective
circuit breaker or
protection equipment has
tripped out.
a) Missing phase. Re-establish all phases.
b) Pump momentarily overloaded. If the fault does not disappear automatically, find
the cause and remedy the fault.
c) Impeller clogged by impurities. Clean impeller as required.
d) Motor protective circuit breaker not set correctly. Set the motor protective circuit breaker as
required according to rated current.
e) Thermal switches tripped out. Insufficient motor
cooling.
Re-establish motor cooling.
f) Moisture switch in motor tripped out. Contact an authorised service workshop.
g) Motor cable defective. Contact an authorised service workshop.
h) Fluctuating voltage. Re-establish correct voltage supply. Permissible
deviation is - 10 %/+ 10 %.
3. Pump runs but does not
deliver the rated flow.
a) Wrong direction of rotation. Exchange two phases to the motor.
b) Impeller loose or worn. Tighten or replace the impeller.
c) Pump or pipework blocked by impurities. Clean as required.
d) Pump head too high. Measure the differential pressure and compare
the value with the pump curve. Remove the
blockage in the discharge pipe.
e) Valves closed or blocked.
Non-return valve not operating.
Clean or replace valves as required.
f) Air in pump or suction pipe. Vent the pump and suction pipe. Increase the
stop level in the tank.
g) Pumped liquid too dense. Dilute the liquid.
h) Pump not properly connected to auto coupling. Pump down the liquid level in tank. Lift out the
pump and relocate the pump on the auto
coupling.
i) Leakage in pipe work. Repair the pipe work.
j) Pump tank flushing system inadvertently activated. Check function and repair as required.
4. Pump starts, but stops
immediately.
a) Clogged pump causes motor-protective circuit
breaker to trip out.
Clean the pump.
b) Overheated motor causes thermal switches to trip
out.
Allow pump to cool. Clean the pump.
c) Level switch out of adjustment or defective. Clean or set level switch or replace as required.
5. Pump vibrating or
emitting excessive noise.
a) Pump partly choked by impurities. Clean the pump.
b) Wrong direction of rotation. Interchange two phases to the motor.
c) Pump operates outside specified operating range. Re-establish proper operating conditions.
d) Pump defective. Repair the pump or contact an authorised
workshop, if necessary.
e) Pump not properly connected to auto coupling. Pump down the liquid level in tank. Lift out the
pump and relocate the pump on the auto
coupling.
f) Pump cavitates. Clean the suction pipe.
g) Impeller not in balance. Contact an authorised service workshop.
h) Base stand, auto coupling, ring stand or guide rails
not installed correctly.
Install the components correctly.
6. Low motor liquid level. a) Upper mechanical seal leaking. Contact an authorised service workshop.
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