Fault Finding Chart - Grundfos SP Serie Montage- Und Betriebsanleitung

9. Fault finding chart

Fault
1. The pump does not run.
2. The pump runs but gives
no water.
3. The pump runs at
reduced capacity.
4. Frequent starts and
stops.
Cause
a) The fuses are blown.
b) The ELCB or the voltage-operated ELCB
has tripped out.
c) No electricity supply.
d) The motor starter overload has tripped out.
e) Motor starter/contactor is defective.
f) Starter device is defective.
g) The control circuit has been interrupted or
is defective.
h) The dry-running protection has cut off the
the electricity supply to the pump, due to low
water level.
i) The pump/submersible drop cable is
defective.
a) The discharge valve is closed.
b) No water or too low water level in borehole.
c) The non-return valve is stuck in its shut
position.
d) The inlet strainer is choked up.
e) The pump is defective.
a) The drawdown is larger than anticipated.
b) Wrong direction of rotation.
c) The valves in the discharge pipe are partly
closed/blocked.
d) The discharge pipe is partly choked by
impurities (ochre).
e) The non-return valve of the pump is partly
blocked.
f) The pump and the riser pipe are partly
choked by impurities (ochre).
g) The pump is defective.
h) Leakage in the pipework.
i) The riser pipe is defective.
a) The differential of the pressure switch
between the start and stop pressures is too
small.
b) The water level electrodes or level switches
in the reservoir have not been installed
correctly.
c) The non-return valve is leaking or stuck half-
open.
d) The volume of air in the pressure/diaphragm
tank is too small.
e) The pressure/diaphragm tank is too small.
f) The diaphragm of the diaphragm tank is
defective.
Remedy
Replace the blown fuses. If the new ones blow too, the
electric installation and the submersible drop cable
should be checked.
Cut in the circuit breaker.
Contact the electricity supply authorities.
Reset the motor starter overload (automatically or
possibly manually). If it trips out again, check the
voltage. Is the voltage OK, see items e) - h).
Replace the motor starter/contactor.
Repair/replace the starter device.
Check the electric installation.
Check the water level. If it is OK, check the water level
electrodes/level switch.
Repair/replace the pump/cable.
Open the valve.
See item 3 a).
Pull out the pump and clean or replace the valve.
Pull out the pump and clean the strainer.
Repair/replace the pump.
Increase the installation depth of the pump, throttle the
pump or replace it by a smaller model to obtain a
smaller capacity.
See section 5.7.1 Checking of direction of rotation.
Check and clean/replace the valves, if necessary.
Clean/replace the discharge pipe.
Pull out the pump and check/replace the valve.
Pull out the pump. Check and clean or replace the
pump, if necessary. Clean the pipes.
Repair/replace the pump.
Check and repair the pipework.
Replace the riser pipe.
Increase the differential. However, the stop pressure
must not exceed the operating pressure of the
pressure tank, and the start pressure should be high
enough to ensure sufficient water supply.
Adjust the intervals of the electrodes/level switches to
ensure suitable time between the cutting-in and
cutting-out of the pump. See installation and operating
instructions for the automatic devices used. If the
intervals between stop/start cannot be changed via the
automatics, the pump capacity may be reduced by
throttling the discharge valve.
Pull out the pump and clean/replace the non-return
valve.
Adjust the volume of air in the pressure/diaphragm
tank in accordance with its installation and operating
instructions.
Increase the capacity of the pressure/diaphragm tank
by replacing or supplementing with another tank.
Check the diaphragm tank.
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