Fault Finding - Grundfos CM 1 Manual De Instrucciones

12. Fault finding

Warning
Before removing the terminal box cover, switch off the power supply. Make sure that the
power supply cannot be accidentally switched on.
Warning
The pumped liquid may be scalding hot and under high pressure. Before any removal or
dismantling of the pump, the system must therefore be drained, or the isolating valves on
either side of the pump must be closed.
Fault
1. The pump does not run.
2. Motor-protective circuit
breaker has tripped (trips
out immediately when
power supply is switched
on).
3. The motor-protective circuit
breaker trips out
occasionally.
4. The motor-protective circuit
breaker has not tripped out,
but the pump is
inadvertently out of
operation.
5. The pump performance is
unstable.
18
Cause
a) Supply failure.
b) Fuses are blown.
c) Motor protection tripped.
d) Control-current circuit
defective.
a) Fuses are blown.
b) Contacts of the
motor-protective circuit
breaker or magnet coil
defective.
c) Cable connection is loose or
faulty.
d) Motor winding is defective.
e) The pump is mechanically
blocked.
f) The setting of the
motor-protective circuit
breaker is too low.
a) The setting of the
motor-protective circuit
breaker is too low.
b) Periodic supply failure.
c) Periodically low voltage.
a) See 1. a), b), d) and 2. e).
a) Pump inlet pressure too low.
b) Suction pipe is partly blocked
by impurities.
c) Leakage in suction pipe.
d) Air in suction pipe or pump.
Remedy
Switch on the switch.
Check cables and cable connections
for defects and loose connections.
Check cables and cable connections
for defects, and replace the fuses.
See 2. a), b), c), d), e), f).
Repair or replace the control-current
circuit.
See 1. b).
Replace the contacts of the
motor-protective circuit breaker, the
magnet coil or the entire
motor-protective circuit breaker.
Check cables and cable connections
for defects, and replace the fuses.
Repair or replace the motor.
Switch off the power supply, and
clean or repair the pump.
Set the motor-protective circuit
breaker according to the rated
current of the motor (I ).
1/1
See nameplate.
See 2. f).
See 2. c).
Check cables and cable connections
for defects and loose connections.
Check that the supply cable of the
pump is correctly sized.
Check the inlet conditions of the
pump.
Remove and clean the suction pipe.
Remove and repair the suction pipe.
Vent the suction pipe/pump.
Check the inlet conditions of the
pump.