Fault Finding The Product 11 Pump - Grundfos Unilift AP12 Serie Instrucciones De Instalación Y Funcionamiento

7. Fault finding the product
Warning
Before starting any work on the product,
make sure that the power supply has been
switched off and that it cannot be
accidentally switched on.
Fault
1. The motor does not
start.
2. The motor protection/
thermal relay trips
after a short time of
operation.
3. The pump runs
constantly or gives
too little water.
4. The pump runs but
gives no water.
Cause
a) No power supply.
b) The pump was stopped by the level
switch.
c) The fuses have blown.
d) The motor protection/thermal relay has
tripped.
e) The impeller is blocked by impurities.
f) Short circuit in cable or motor.
a) The liquid temperature is too high.
b) The impeller is blocked or partly blocked
by impurities.
c) Phase failure.
d) Too low voltage.
e) The overload setting of the motor-
protective circuit breaker is too low.
f) Incorrect direction of rotation. See
section 3.1 Checking the direction of
rotation.
a) The pump is partly blocked by impurities. Clean the pump.
b) The outlet pipe or valve is partly blocked
by impurities.
c) The impeller is not properly fixed to the
shaft.
d) Incorrect direction of rotation. See
section 3.1 Checking the direction of
rotation.
e) Incorrect setting of level switch.
f) The pump is too small for the application. Replace the pump.
g) The impeller is worn.
a) The pump is blocked by impurities.
b) The outlet pipe or non-return valve
blocked by impurities.
c) The impeller is not properly fixed to the
shaft.
d) Air in pump.
e) The liquid level is too low. The inlet
strainer is not completely submerged in
the pumped liquid.
f) The level switch does not move freely.
Remedy
Connect the power supply.
Adjust or replace the level
switch.
Replace the fuses.
Wait until the motor protection
trips in again/reset the relay.
Clean the impeller.
Replace the defective part.
Use another pump type.
Clean the pump.
Call an electrician.
Call an electrician.
Adjust the setting.
Reverse the direction of
rotation.
Clean the outlet pipe.
Tighten the impeller.
Reverse the direction of
rotation.
Adjust the level switch.
Replace the impeller.
Clean the pump.
Clean the outlet pipe.
Tighten the impeller.
Vent the pump and the outlet
pipe.
Submerge the pump in the liquid
or adjust the level switch.
Make the level switch move
freely.
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