Fault Finding The Product - Grundfos Unilift AP35B Installation And Operating Instructions Manual

9. 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
does not deliver
the rated flow.
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
8.1 Cleaning the pump.
Replace the defective part.
Contact your Grundfos service
partner.
Clean the impeller. See section
8.1 Cleaning the pump.
Consult an electrician.
Consult an electrician.
Adjust the setting.
Clean the pump. See section
8.1 Cleaning the pump.
Clean the outlet pipe.
Tighten the impeller.
Adjust the float switch setting.
Replace the pump.
Replace the impeller.
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