Fault Finding Chart; Disposal - Grundfos AP51 Serie Montage- Und Betriebsanleitung

8. Fault finding chart

Make sure that all power supplies have been switched off and that all rotating parts have
stopped moving before attempting to diagnose any fault.
Fault
1. Motor does not start. Fuses
blow or motor starter trips out
immediately.
Caution: Do not start again!
2. Pump operates, but motor
starter trips out after a short
while.
3. Pump operates at
below-standard performance
and power consumption.
4. Pump operates, but gives no
liquid.

9. Disposal

This product or parts of it must be disposed of in an
environmentally sound way:
1. Use the public or private waste collection service.
2. If this is not possible, contact the nearest
Grundfos company or service workshop.
10
Cause
a) Supply failure; short-circuit;
earth-leakage fault in cable or
motor winding.
b) Fuses blow due to use of
wrong type of fuse.
c) Impeller blocked by impurities. Clean the impeller.
d) Level switch out of adjustment
or defective.
a) Low setting of thermal relay in
motor starter.
b) Increased current
consumption due to large
voltage drop.
c) Impeller blocked by impurities.
Increased current
consumption in all three
phases.
a) Impeller blocked by impurities.
b) Wrong direction of rotation.
a) Discharge valve closed or
blocked.
b) Non-return valve blocked.
c) Air in pump.
Subject to alterations.
Remedy
Have the cable and motor checked
and repaired by a qualified
electrician.
Install fuses of the correct type.
Check the level switch.
Set the relay in accordance with
the specifications on the
nameplate.
Measure the voltage between
motor phases. Tolerance: ± 10 %.
Clean the impeller.
Clean the impeller.
Check the direction of rotation and
possibly interchange two phases,
see section 6.1 Direction of
rotation.
Check discharge valve and
possibly open and/or clean.
Clean non-return valve.
Vent the pump.