Grundfos CMV 3, Installation And Operating Instructions Manual

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8. Fault finding the product
DANGER
Electric shock
Death or serious personal injury
- Before starting any work on the product,
make sure that the power supply has
been switched off and that it cannot be
accidentally switched on.
WARNING
Corrosive liquids
Death or serious personal injury
- Wear personal protective equipment.
WARNING
Toxic liquids
Death or serious personal injury
- Wear personal protective equipment.
CAUTION
Hot or cold liquid
Minor or moderate personal injury
- Wear personal protective equipment.
Fault Cause Remedy
1. The pump does not run. a) Supply failure. Switch on the switch.
Check cables and cable connections
for defects and loose connections.
b) The motor protection has
tripped.
See 2 a), b), c), d), e).
c) The control-current circuit is
defective. Repair or replace the control-current
circuit.
2. The motor-protective circuit
breaker has tripped. It trips
immediately when the
power supply is switched
on. a) Contacts of the
motor-protective circuit
breaker or magnet coil are
defective. Replace the contacts of the
motor-protective circuit breaker, the
magnet coil or the entire
motor-protective circuit breaker.
b) A cable connection is loose or
faulty. Check cables and cable connections
for defects, and replace the fuses.
c) The motor winding is
defective.
Repair or replace the motor.
d) The pump is mechanically
blocked. Switch off the power supply, and
clean or repair the pump.
e) The setting of the
motor-protective circuit
breaker is too low. Set the motor-protective circuit
breaker according to the rated
current of the motor (I
1/1
).
See the nameplate.
3. The motor-protective circuit
breaker trips occasionally. a) The setting of the
motor-protective circuit
breaker is too low.
See 2 e).
b) Periodic supply fault. See 2 b).
c) Periodically low voltage. Check cables and cable connections
for defects and loose connections.
Check that the power supply cable of
the pump is correctly sized.
4. The motor-protective circuit
breaker has not tripped, but
the pump is inadvertently
out of operation. a) See 1 a), b), c) and 2 d).
5. The pump performance is
unstable. a) The pump inlet pressure is too
low.
Check for proper inlet conditions.
b) The inlet pipe is partly blocked
by impurities.
Remove and clean the inlet pipe.
c) Leakage in the inlet pipe. Remove and repair the inlet pipe.
d) Air in the inlet pipe or pump. Vent the inlet pipe or pump.
Check for proper inlet conditions.