Grundfos CU 362 Instrucciones De Instalación Y Funcionamiento página 28

8. Fault finding
WARNING
Electric shock
Death or serious personal injury
‐
Before making any connections in pumps, terminal
boxes or 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.
8.1 Pumps do not run when started
Cause
CU 362 fault.
Power supply disconnected.
Main switch cut out.
Main switch defective.
Motor protection tripped.
Motor defective.
Sensor fault.
Cable defective.
No water in pump pit.
Level control fault.
External on/off switch switched
off.
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Remedy
• Reset alarms, or replace the
CU 362.
• Switch on the power supply.
• Replace fuse.
• Replace the main switch.
• Cut in the main switch.
• Replace the main switch.
• Check the setting.
• Motor defective.
• Open thermistor.
• Phase failure.
• Contact Grundfos.
• Repair or replace the motor.
• Check sensor configuration.
• Replace the sensor.
• Repair or replace the cable.
• Wait until the level control
activates a pump.
• Check level control
configuration.
• Replace the sensor/float
switch.
• Switch on the on/off switch.
8.2 Pumps start, but stop immediately
Cause
Dry running or no inlet
pressure.
Motor protection tripped.
Level control fault.
8.3 Pump performance unstable
Cause
Suction port blocked by
impurities.
Suction pipe or pumps partially
blocked by impurities.
Pumps suck air.
Valves closed.
8.4 Pumps are running, but deliver no water
Cause
Valves closed.
Suction pipe or pumps blocked
by impurities.
Non-return valve blocked in
closed position.
8.5 Pumps start and stop frequently
Cause
Incorrect distance between
start and stop levels.
Remedy
• Wait until the level control
activates a pump.
• Check the setting.
• Motor defective.
• Check level control
configuration.
• Replace the sensor/float
switch.
Remedy
• Clean the pump.
• Clean the suction pipe,
strainer or pumps.
• Incorrect positioning of pump
relative to level control (dry
running).
• Open the valves.
Remedy
• Open the valves.
• Clean the suction pipe or
pumps.
• Clean the non-return valve.
The non-valve must be able to
move freely.
Remedy
• Set start and stop levels
correctly.