Lowara NSCF - The electric pump starts, but the thermal protector trips a varying time after; The electric pump starts, but the systems general protection is activated; The electric pump starts, but the systems residual current device (RCD) is activated; The pump runs but delivers too little or no liquid

7.5 The electric pump starts, but
the thermal protector trips a varying
time after
Cause Remedy
There are foreign ob-
jects (solids or fibrous
substances) inside the
pump which have jam-
med the impeller.
Contact the local sales and
service representative.
The pumps delivery
rate is higher than the
limits specified on the
data plate.
Partially close the on-off
valve down stream until the
delivery rate is equal or
less than the limits speci-
fied on the data plate.
The pump is overload-
ed because it is pump-
ing liquid that is too
dense and viscous.
Check the actual power re-
quirements based on the
characteristics of the
pumped liquid and replace
the motor accordingly.
The motor bearings
are worn.
Contact the local sales and
service representative.
7.6 The electric pump starts, but
the system's general protection is
activated
Cause Remedy
A short circuit in the electri-
cal system.
Check the electrical
system.
7.7 The electric pump starts, but
the system's residual current device
(RCD) is activated
Cause
Remedy
There is an ground
(earth) leakage.
Check the insulation of the
electrical system components.
7.8 The pump runs but delivers too
little or no liquid
Cause
Remedy
There is air inside
the pump or the pip-
ing.
• Bleed the air
The pump is not cor-
rectly primed.
Stop the pump and repeat the
prime procedure.
If the problem continues:
• Check that the mechani-
cal seal is not leaking.
• Check the suction pipe for
perfect tightness.
• Replace any valves that
are leaking.
The throttling on the
delivery side is too
extensive.
Open the valve.
Cause Remedy
Valves are locked in
closed or partially
closed position.
Disassemble and clean the
valves.
The pump is clog-
ged.
Contact the local sales and
service representative.
The piping is clog-
ged.
Check and clean the pipes.
The rotation direc-
tion of the impeller is
wrong
(three-phase ver-
sion)
.
Change the position of two of
the phases on the terminal
board of the motor or in the
electric control panel.
The suction lift is too
high or the flow re-
sistance in the suc-
tion pipes is too
great.
Check the operating condi-
tions of the pump. If necessa-
ry, do the following:
• Decrease the suction lift
• Increase the diameter of
the suction pipe.
7.9 The electric pump stops, and
then rotates in the wrong direction
Cause Remedy
There is a leakage in one or both
of the following components:
• The suction pipe
• The foot valve or the check
valve
Repair or re-
place the faulty
component.
There is air in the suction pipe. Bleed the air.
7.10 The pump starts up too
frequently
Cause
Remedy
There is a leakage in one or
both of the following compo-
nents:
• The suction pipe
• The foot valve or the check
valve
Repair or replace
the faulty compo-
nent.
There is a ruptured membrane
or no air pre-charge in the pres-
sure tank.
See the relevant
instructions in the
pressure tank
manual.
7.11 The pump vibrates and
generates too much noise
Cause
Remedy
Pump cavitation Reduce the required flow rate by
partially closing the on-off valve
downstream from the pump. If
the problem persists check the
operating conditions of the pump
(for example height difference,
en - Original instructions
25