Fault Finding Chart - Grundfos SQ Série Notice D'installation Et De Fonctionnement

10. Fault finding chart

Warning
Before starting any work on the pump/
motor, make sure that the power supply
has been switched off and that it cannot be
accidentally switched on.
Fault
1. The pump does
not run.
2. The pump runs
but gives no
water.
3. The pump runs at
reduced capacity.
Cause
a) The fuses in the electric
installation are blown.
b) The ELCB or the voltage-operated
ELCB has tripped out.
c) No power supply.
d) The motor protection has cut off
the power supply due to overload.
e) The pump/submersible drop cable
is defective.
f) Overvoltage or undervoltage has
occurred.
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
closed position.
d) The suction strainer is choked up.
e) The pump is defective.
a) The drawdown is larger than
anticipated.
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.
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 power supply authorities.
Check whether the motor/pump is blocked.
Repair/replace the pump/cable.
Check the power 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 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.
Check the power supply.
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