Fault Finding The Product - Grundfos Unilift AP35B Installations- Und Bedienungsanleitung

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 the cable or motor.
a) The liquid temperature is too high.
b) Impeller blocked or partly blocked by
impurities.
c) Phase failure.
d) Too low voltage.
e) Overload setting of the motor-protective
circuit breaker too low.
f) Incorrect direction of rotation. See
section 3.1 Checking the direction of
rotation.
a) The pump is partly blocked by
impurities.
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.
g) The impeller is worn.
a) The pump is blocked by impurities.
b) The outlet pipe or non-return valve is
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 pump
inlet 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 pump.
Clean the outlet pipe.
Tighten the impeller.
Reverse the direction of rotation.
Adjust the level switch.
Replace the pump.
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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