Fault Finding - Grundfos Hydro Multi-E Montage- Und Betriebsanleitung

17. Fault finding

Warning
Before starting fault finding, switch off the power supply for at least 5 minutes.
Make sure that it cannot be accidentally switched on.
Fault Cause
1. The Hydro Multi-E does a) The actual pressure is higher than or
not run when started.
b) Power supply disconnected.
c) Circuit breakers cut out.
d) Internal motor protection activated.
e) Circuit breaker defective.
f)
g) Pressure transmitter fault.
2. The Hydro Multi-E a) Dry running or no inlet pressure.
starts, but stops
immediately afterwards.
The operating pressure
is not reached.
3. The Hydro Multi-E is a) Pressure transmitter fault.
stopped and cannot
restart.
b) Control unit fault.
4. Unstable water delivery a) Inlet pressure too low.
from Hydro Multi-E
b) Suction pipe or pumps partly blocked by
(applies only to very low
consumption).
c) Pumps suck air.
d) Pressure transmitter defective.
5. Pumps are running, but a) Suction pipe or pumps blocked by
deliver no water.
b) Non-return valve blocked in closed
c) Suction pipe leaky.
d) Air in suction pipe or pumps.
6. The Hydro Multi-E is a) Cable broken or short-circuited
unable to reach the
setpoint.
b) Pump 2 or 3 out of operation.
7. Leakage from a shaft a) Shaft seal defective.
seal.
b) CRE and CRIE pumps:
8. Noise. a) The pumps are cavitating.
b) CRE and CRIE pumps: The pumps do
9. Very frequent starts and a) Wrong diaphragm tank precharge
stops.
b) The difference between start and stop
20
equal to the setpoint set.
Motor defective.
– Pressure transmitter defective.
– Cable broken or short-circuited.
– Pressure transmitter defective.
– Cable broken or short-circuited.
– Power supply disconnected on pump 1.
– Control unit defective.
impurities.
impurities.
position.
(GENIbus communication between
pump 1 and pump 2/3).
Height adjustment of pump shaft
inaccurate.
not rotate freely (frictional resistance)
due to inaccurate height adjustment of
the pump shaft.
pressure.
pressures is too small.
Note: This situation will only arise if
emergency operation is installed.
Remedy
Wait until the pressure has dropped, or lower the pressure
on the discharge side of the Hydro Multi-E, and check that
the booster system starts.
Connect the power supply.
Correct the fault and cut in the circuit breakers.
Contact Grundfos.
Replace the circuit breaker.
Repair or replace the motor.
Replace the pressure transmitter. Transmitters with
0-20 mA or 4-20 mA output signals are monitored by the
Hydro Multi-E.
Repair or replace the cable.
Check the supply of water to the Hydro Multi-E. When the
inlet pressure has been reestablished, the pumps will
restart after 15 seconds.
Replace the pressure transmitter. Transmitters with
0-20 mA or 4-20 mA output signals are monitored by the
Hydro Multi-E.
Repair or replace the cable.
Connect the power supply.
Replace the terminal box of pump 1.
Contact Grundfos.
Check the suction pipe and possible suction strainer.
Clean the suction pipe or pumps.
Check the suction pipe for leakages.
Replace the pressure transmitter.
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 the pumps. Check the suction pipe for leakages.
Repair or replace the cable.
Connect the power supply to the pump and check the pump
condition.
Replace the shaft seal.
Readjust the shaft height.
Clean the suction pipe or pumps and possible suction
strainer.
Readjust the shaft height. See the CR, CRI, CRN
installation and operating instructions supplied with the
Hydro Multi-E.
Check the precharge pressure.
Increase the differential pressure setting on each pressure
switch.