Grundfos TP Series, Installation And Operating Instructions Manual

Page: 17 / 212

English (GB)
17
12. Fault finding chart
Warning
Before removing the terminal box cover and before any removal/dismantling of the pump,
make sure that the electricity supply has been switched off and that it cannot be accidentally
switched on.
Fault Cause
1. Motor does not run when
started. a) Supply failure.
b) Fuses blown.
c) Motor starter overload has tripped out.
d) Main contacts in motor starter are not making contact or the coil is
faulty.
e) Control circuit fuses are defective.
f) Motor is defective.
2. Motor starter overload trips
out immediately when supply
is switched on. a) One fuse is blown.
b) Contacts in motor starter overload are faulty.
c) Cable connection is loose or faulty.
d) Motor winding is defective.
e) Pump mechanically blocked.
f) Overload setting too low.
3. Motor starter overload trips
out occasionally. a) Overload setting too low.
b) Supply voltage periodically too low or too high.
c) Differential pressure across pump too low, see section 9.3 Starting .
4. Motor starter has not tripped
out but the pump does not
run. a) Supply failure.
b) Fuses blown.
c) Main contacts in motor starter are not making contact or the coil is
faulty.
d) Control circuit fuses are defective.
5. Pump capacity not constant. a) Pump inlet pressure is too low.
b) Suction pipe/pump partly blocked by impurities.
c) Pump draws in air.
6. Pump runs but gives no
water. a) Suction pipe/pump blocked by impurities.
b) Foot or non-return valve blocked in closed position.
c) Leakage in suction pipe.
d) Air in suction pipe or pump.
e) Motor rotates in the wrong direction.
7. Pump runs backwards when
switched off. a) Leakage in suction pipe.
b) Foot or non-return valve defective.
c) Foot or non-return valve blocked in open or partly open position.
8. Leakage in shaft seal. a) Shaft seal is defective.
9. Noise. a) Pump is cavitating.
b) Pump does not rotate freely (frictional resistance) because of
incorrect pump shaft position.
c) Frequency converter operation:
See section
8.1 Frequency converter operation .
d) Resonance in the installation.
e) Foreign bodies in the pump.