Fault Finding - Grundfos JP 6 Installation And Operating Instructions Manual

10. Fault finding

Warning
Before starting fault finding, switch off
the power supply. Make sure that the
power supply cannot be accidentally
switched on.
Fault
1. The pump does
not start.
2. The pump runs,
but gives no water
or delivers a
reduced quantity
of water.
3. The pump runs, but
gives no water or
delivers a reduced
quantity of water at
high pressure.
12
Cause
a) Supply failure.
b) Pump blocked by impurities.
c) Motor defective.
d) Three-phase motors:
The motor-protective circuit
breaker has tripped.
a) Pump is not filled with water.
b) Suction pipe blocked by
impurities.
c) Pump blocked by impurities.
d) Suction lift is too high (over 7
metres).
e) Suction pipe is too long.
f) Diameter of suction pipe is
too small.
g) Suction pipe is not immersed
deeply enough.
h) Suction pipe is leaking.
i) Ejector valve setting is
incorrect (only pumps fitted
with ejector valve).
j) Direction of rotation is
incorrect (three-phase
pumps).
a) Discharge pipe blocked.
Remedy
Cut in the circuit breaker or replace the fuses.
If the new fuses also blow, check the electric
installation.
Clean the pump. Check or replace the strainer
in the suction pipe.
Repair or replace the motor. *
Cut in the motor-protective circuit breaker.
If the problem still persists, check these two
possible causes:
• Impeller stuck.
Clean the pump according to section 8.1.
• Motor defective.
Repair or replace the motor. *
Prime the pump. See section
Clean the pump. Check or replace the strainer
in the suction pipe.
Clean the pump. Check or replace the strainer
in the suction pipe.
Change the position of the pump.
Change the position of the pump.
Replace the suction pipe.
Make sure that the suction pipe is immersed
sufficiently.
Repair or replace the pipe.
Set the valve. See section 5.2.
Interchange two phases.
Clean pipe or open isolating valves, if fitted.
Check that no additional work is being carried
out in the system.
7.