Fault Finding - Grundfos Hydro Multi-B Instrucciones De Instalación Y Funcionamiento

13. Fault finding

Warning
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.
Fault
The pumps are not running.
The pumps start, but stop immediately.
The operating pressure is not reached.
The Hydro Multi-B is stopped and
cannot restart.
Unstable water supply from the
Hydro Multi-B.
Pumps are running, but deliver no
water.
The Hydro Multi-B is unable to reach
the setpoint.
Leakage from the shaft seal.
Noise.
Very frequent starts and stops.
Possible cause
Current pressure is higher than or equal to
the setpoint.
Power supply disconnected.
Main switch cut out.
Main switch is defective.
Motor protection is activated.
Motor is defective.
Pressure transmitter fault:
• Pressure transmitter is defective.
Cable is broken or short-circuited.
Water shortage or no inlet pressure.
Pressure transmitter fault:
• Pressure transmitter is defective.
Cable is broken or short-circuited.
CU 323 fault:
• Power supply is disconnected.
The CU 323 is defective.
Inlet pressure is too low.
Suction pipe or pumps partly blocked by
impurities.
Pumps suck air.
Pressure transmitter defective.
The valves are closed.
Suction pipe or pumps blocked by
impurities.
Non-return valve blocked in closed position.
Suction pipe leaky.
Air in suction pipe or pumps.
Too high consumption.
Too many standby pumps selected.
Pipe fracture or leakage in the system.
Shaft seal is defective.
The pumps are cavitating.
Wrong diaphragm tank precharge pressure.
Remedy
Wait until the pressure has dropped, or lower
the pressure on the discharge side of the
Hydro Multi-B, and check that the pumps start.
Connect the power supply.
Cut in the main switch.
Replace the main switch.
Contact Grundfos.
Repair or replace the motor.
Replace the pressure transmitter.
0-10 bar or 0- 6 bar transmitters with 0-10 V,
0-20 mA or 4-20 mA output signals are
monitored by the Hydro Multi-B.
Repair or replace the cable.
Re-establish the supply of water to the
Hydro Multi-B. When the inlet pressure has
been re-established, press [Reset] to restart the
system.
Replace the pressure transmitter.
0-10 bar or 0-16 bar transmitters with 0-10 V,
0-20 mA or 4-20 mA output signals are
monitored by the Hydro Multi-B.
Repair or replace the cable.
Connect the power supply.
Contact Grundfos.
Check the suction pipe and the suction strainer,
if any.
Clean the suction pipes, strainer or pumps.
Check the suction pipe for leakages.
Replace the transmitter.
Open the valves.
Clean the suction pipe or pumps.
Clean the non-return valve. The non-return
valve must move freely.
Check the suction pipe for leakages.
Vent and prime the pumps. Check the suction
pipe for leakages.
• Reduce consumption, if possible.
• Install a bigger Hydro Multi-B booster
system.
Reduce the number of standby pumps.
Check the system, and repair damages,
if necessary.
Replace the shaft seal.
Clean the suction pipe/pumps and possibly the
suction strainer.
Set correct precharge pressure.
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