Fault Finding; The Motor Does Not Start; The Motor Protection Or Thermal Relay Trips After A Short Time Of Operation - Grundfos UNILIFT APG Installation And Operating Instructions Manual

9. Fault finding

DANGER
Electric shock
Death or serious personal injury
‐
Switch off the power supply before you
start any work on the product.Make
sure that the power supply cannot be
switched on accidentally.
CAUTION
Sharp element
Minor or moderate personal injury
‐
Wear personal protective equipment.

9.1 The motor does not start

Cause
No power supply.
The pump was stopped by the float switch.
The fuses have blown.
The motor protection or thermal relay has tripped.
The impeller is blocked by impurities.
Short circuit in the cable or motor.

9.2 The motor protection or thermal relay trips after a short time of operation

Cause
The liquid temperature is too high.
The impeller is blocked or partly blocked by
impurities.
Phase failure.
Too low voltage.
The overload setting of the motor-protective circuit
breaker is too low.
Incorrect direction of rotation.
Related information
6.1 Checking the direction of rotation
20
CAUTION
Toxic material
Minor or moderate personal injury
‐
The product will be classified as conta-
minated if it has been used for a liquid
which is injurious to health or toxic.
‐
Wear personal protective equipment.
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.
Replace the defective part.
Remedy
Use another pump type. Contact your local Grundfos
supplier or sales support.
Clean the pump.
Call an electrician.
Call an electrician.
Adjust the setting.
Reverse the direction of rotation.