Fault Finding The Product - Grundfos Unilift AP12 Installation And Operating Instructions Manual

8. Fault finding the product

DANGER
Electric shock
Death or serious personal injury
- Switch off the power supply before
starting any work on the product.
Make sure that the power supply
cannot be accidentally switched
on.
Fault
1. The motor does
not start.
2. The motor
protection or the
thermal relay
trips after a short
time of operation.
3. The pump runs
constantly or
gives insufficient
water.
Cause
a) No power supply.
b) The motor is switched off by the
float switch.
c) The fuses are blown.
d) The motor protection or thermal
relay has tripped.
e) The impeller is blocked by
impurities.
f) There is a short circuit in the cable
or motor.
a) The temperature of the pumped
liquid is too high.
b) The impeller is blocked or partly
blocked by impurities.
c) Phase failure.
d) The voltage is too low.
e) The overload setting of the motor-
protective circuit breaker is set too
low.
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) The float switch is set incorrectly.
e) The pump is too small for the
application.
f) The impeller is worn.
Remedy
Connect the power supply.
Adjust or replace the float switch.
Replace the fuses.
Wait until the motor protection
trips in again or reset the relay.
Clean the impeller.
See section 7.1 Cleaning the
pump.
Replace the defective part.
Contact your Grundfos
representative.
Clean the impeller.
See section 7.1 Cleaning the
pump.
Consult an electrician.
Consult an electrician.
Adjust the setting.
Clean the pump.
See section 7.1 Cleaning the
pump.
Clean the outlet pipe or valve.
Tighten the impeller.
Adjust the float switch setting.
Replace the pump.
Replace the impeller.
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