Are the phase currents
Yes
Contact service shop.
uneven or too high?
No
Is the insulation between the
Yes
Contact service shop.
phases and ground in the
stator defective?
(Use insulation tester. With a
1000 V-DC megger, the
insulation between the phases
and between any phase and
ground should be > 1MΩ)
No
Is the density of the pumped
Yes
Dilute the liquid.
liquid too high? (Max density
Change to a more suitable pump.
1100 kg/m
3
, 9.2 lb/gal)
Contact service shop.
No
Fault on overload protection?
Yes
Replace the overload protection.
No
Contact service shop.
3. The pump does not stop.
Is the pump able to empty
No
Check:
the station to the stop level?
- for leakage in pipe and/or discharge
connection.
Yes
- that the impeller is not clogged.
WARNING: disconnect power before
checking the impeller.
- the non-return valve(s).
- that the pump has adequate capacity.
Fault in level sensing
Yes
Clean the level sensors.
equipment?
Check the functioning of level sensors.
Check the contactor and holding circuit.
No
Replace defective items.
Stop level set too low.
Yes
Raise the stop level.
No
Contact service shop.
4. The pump starts-stops-starts in rapid sequence
Does the pump start due to
Yes
Check:
backflow which fills sump to
- that the distance between the start and stop
start level again?
levels is not too small.
- the non-return valve(s).
No
- that the riser is not too long without a
