Fault Finding Chart - Grundfos SQ Instrucciones De Instalación Y Funcionamiento

9. Fault finding chart

Fault Cause
1. The pump does not a) The fuses in the electric installation
run. are blown.
b) The ELCB or the voltage-operated
ELCB has tripped out.
c) No electricity supply.
d) The motor protection has cut off the
electricity supply due to overload.
e) The pump/submersible drop cable is
defective.
f) Overvoltage or undervoltage has
occurred.
2. The pump runs but a) The discharge valve is closed.
gives no water.
b) No water or too low water level in
borehole.
c) The non-return valve is stuck in its
closed position.
d) The suction strainer is choked up.
e) The pump is defective.
3. The pump runs at a) The drawdown is larger than antici-
reduced capacity. pated.
b) The valves in the discharge pipe are
partly closed/blocked.
c) The discharge pipe is partly choked
by impurities (ochre).
d) The non-return valve of the pump is
partly blocked.
e) The pump and the riser pipe are
partly choked by impurities (ochre).
f) The pump is defective.
g) Leakage in the pipework.
h) The riser pipe is defective.
i) Undervoltage has occurred.
4. Frequent starts a) The differential of the pressure
and stops. 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 supply voltage is unstable.
e) The motor temperature gets too
high.
12
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.
Check whether the motor/pump is blocked.
Repair/replace the pump/cable.
Check the electricity supply.
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.
Check and clean/replace the valves, if nec-
essary.
Clean/replace the discharge pipe.
Pull out the pump and check/replace the
valve.
Pull out the pump. Check and clean or re-
place the pump, if necessary. Clean the
pipes.
Repair/replace the pump.
Check and repair the pipework.
Replace the riser pipe.
Check the electricity supply.
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 inter-
vals 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.
Check the electricity supply.
Check the water temperature.