Fault Finding Chart - Grundfos TP Serie Instrucciones De Instalación Y Funcionamiento

10. Fault finding chart

Warning
Before removing the terminal box cover and before removal/dismantling of the pump, make
sure that the electricity supply has been switched off and that it cannot be accidentally
switched on.
Fault
1. Motor does not run when
started.
2. Motor starter overload trips
out immediately when supply
is switched on.
3. Motor starter overload trips
out occasionally.
4. Motor starter has not tripped
out but the pump does not
run.
5. Pump capacity not constant.
6. Pump runs but gives no water. a) Suction pipe/pump blocked by impurities.
7. Pump runs backwards when
switched off.*
8. Leakage in shaft seal.
9. Noise.
10. Pump runs constantly (applies
only to pumps with automatic
start/stop).
11. Period of operation is too long
(applies only to pumps with
automatic start/stop).
* In twin-head pump installations, the standby pump will often rotate slowly.
Cause
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.
a) Supply failure.
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.
a) Overload setting too low.
b) Supply voltage periodically too low or too high.
c) Differential pressure across pump too low.
a) Check the electricity supply.
b) Check fuses.
c) Check main contacts in motor starter and coil.
d) Check the control circuit.
a) Pump inlet pressure is too low.
b) Suction pipe/pump partly blocked by impurities.
c) Pump draws in air.
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.
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.
a) Pump shaft position is incorrect.
b) Shaft seal is defective.
a) Pump is cavitating.
b) Pump does not rotate freely (frictional resistance) because of incorrect
pump shaft position.
c) Frequency converter operation:
- See 6.1 Frequency converter operation.
d) Resonance in the installation.
e) Foreign bodies in the pump.
a) Stop pressure is too high in relation to the required quantity of water.
b) The water consumption is larger than anticipated.
c) Leakage in discharge pipe.
d) The direction of rotation of the pump is incorrect.
e) Pipes, valves or strainer blocked by impurities.
f) Pump controller, if used, is defective.
a) Stop pressure is too high in relation to the required quantity of water.
b) Pipes, valves or strainer blocked by impurities.
c) Pump partly blocked or furred up.
d) The water consumption is larger than anticipated.
e) Leakage in discharge pipe.
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