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18. Fault finding chart
18.1 BMP hp feed pump
Warning
Before starting work on the BMP hp feed pump, make sure that the electricity supply has been switched off and that
it cannot be accidentally switched on.
Fault
Cause
Remedy
1. The pump stops during
operation.
a) No water supply.
The low-pressure switch has cut out.
The level switch has cut out.
Check that the low-pressure switch functions normally
and is adjusted correctly.
Check that the minimum inlet pressure is correct. If not,
check the feed pump.
Check the water level in the water tank.
2. The pump does not run. a) The fuses are blown.
After a cut-out, the cause of a possible short-circuit
must be found.
If the fuses are blown, check whether the motor starter
has been set correctly or is faulty.
If the fuses are hot when they are replaced, check that
the load of the individual phases does not exceed the
motor current during operation. Identify the cause of the
load.
If the fuses are not hot immediately after the cut-out, the
cause of a possible short-circuit must be identified.
Possible fuses in the control circuit must be checked
and defective fuses must be replaced.
b) The motor starter overload unit has tripped
out.
Reset the starter overload. See also sections
and
.
c) The magnetic coil in the motor starter/
contactor is defective (not cutting in).
Replace the coil. Check the coil voltage.
d) The control circuit has cut out or is defective. Check the control circuit and the contacts in the
monitoring devices (low-pressure switch, level switch,
etc.).
e) The motor/supply cable is defective.
Check motor and cable. See section
3. The pump runs, but
gives no water nor
develops any pressure.
a) No or insufficient water supply at the pump
suction port.
Check that the inlet pressure during operation is at least
0 bar. See section
Restart the pump as described in section
b) The piping system or pump is choked up.
Check the piping system and pump.
c) The prefilter is clogged.
Clean the prefilter.
d) The pump is worn.
Replace the wear parts. Contact Grundfos Service.
e) Wrong direction of rotation.
See section
.
4. The pump runs at
reduced capacity.
a) The pump is partly blocked by impurities.
Dismantle, clean and check the pump.
Replace defective parts. Contact Grundfos Service.
b) The pump is defective.
Replace defective parts. Contact Grundfos Service.
c) The prefilter is clogged.
Clean the prefilter.
d) The motor speed is too low.
Check the electricity supply.
Contact the electricity supply authorities, if necessary.
If a frequency converter is used, adjust the speed.
