Manual - Lowara NSC Serie Manual De Instalación, Funcionamiento Y Mantenimiento

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

manual.

25