Fault Finding - Grundfos JPC Series Installation And Operating Instructions Manual

6. 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 or just
a little water.
3. The pump runs, but
gives no water or
delivers a reduced
quantity of water at
high pressure.
4. The motor cuts out
during operation.
8
Cause
a) Supply failure.
b) The pump is blocked by
impurities.
c) The motor is defective.
a) Pump is not filled with water.
b) The inlet pipe is blocked by
impurities.
c) The pump is blocked by
impurities.
d) The suction lift is too high
(over 7 metres).
e) The inlet pipe is too long.
f) Diameter of inlet pipe is too
small.
g) The inlet pipe is not immersed
deeply enough.
h) The inlet pipe is leaking.
a) The discharge pipe is
blocked.
a) Single-phase motors:
The thermal switch in the
motor has tripped due to
overheating.
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 inlet pipe.
Replace the pump.
Prime the pump. See section
Clean the pump. Check or replace the strainer
in the inlet pipe.
Clean the pump. Check or replace the strainer
in the inlet pipe.
Change the position of the pump.
Change the position of the pump.
Replace the inlet pipe.
Make sure that the inlet pipe is immersed
sufficiently.
Repair or replace the pipe.
Clean pipe or open isolating valves, if fitted.
Check that no additional work is being carried
out in the system.
The thermal switch will cut in automatically
when the motor has cooled sufficiently.
If the problem still persists, check these two
possible causes:
• Impeller stuck.
Clean the pump.
• Motor defective.
Replace the pump.
3.