Grundfos CU 362 User Manual

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.
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English (GB)

Grundfos CU 362 Specifications

General

Brand	Grundfos
Model	CU 362
Category	Control Unit
Language	English