9. Fault finding
DANGER
Warning
Death or serious personal injury
‐
Before making any connections in pumps, terminal
boxes or the control cabinet, make sure that the power
supply has been switched off for at least 5 minutes
and that it cannot be accidentally switched on.
9.1 Pumps do not run when started
Cause
Remedy
CU 362 fault
•
Reset alarms, or replace CU
362.
Power supply disconnected
•
Switch on the power supply.
•
Replace the fuse.
•
Replace the main switch.
Main switch cut out
•
Cut in the main switch.
Main switch defective
•
Replace the main switch.
Motor protection tripped
•
Check the setting.
•
Contact Grundfos if the motor
is defective.
•
Open thermistor.
•
Check the phase.
•
Contact Grundfos.
Motor defective
•
Repair or replace the motor.
Sensor fault
•
Check the sensor
configuration.
•
Replace the sensor.
Cable defective
•
Repair or replace the cable.
No water in pump pit
•
Wait until the level control
activates a pump.
Level control fault
•
Check the level control
configuration.
•
Replace the sensor/float
switch.
External on/off switch switched
off
•
Switch on the on/off switch.
9.2 Pumps start but stop immediately
Cause
Remedy
Dry running or no inlet pressure •
Wait until the level control
activates a pump.
Motor protection tripped
•
Check the setting.
•
Contact Grundfos if the motor
is defective.
Level control fault
•
Check the level control
configuration.
•
Replace the sensor/float
switch.
9.3 Pump performance is unstable
Cause
Remedy
Suction port blocked by
impurities
•
Clean the pump.
Suction pipe or pumps partially
blocked by impurities
•
Clean the suction pipe,
strainer or pumps.
Pumps suck air
•
Position the pump correctly
relative to level control (dry
running).
Valves closed
•
Open the valves.
9.4 Pumps are running but deliver no water
Cause
Remedy
Valves closed
•
Open the valves.
Suction pipe or pumps blocked
by impurities
•
Clean the suction pipe or
pumps.
Non-return valve blocked in
closed position
•
Clean the non-return valve.
The non-return valve must be
able to move freely.
9.5 Pumps start and stop frequently
Cause
Remedy
Incorrect distance between
start and stop levels
•
Set the start and stop levels
correctly.
67
English (GB)
