Fault Finding - Grundfos POMONA series Montage- Und Betriebsanleitung

13. Fault finding

Warning
Before removing the terminal box cover and carrying
out any work on the pump, make sure that the power
supply has been switched of and that it cannot be
accidentally switched on. Drain the pump.
Fault Cause
1. Pump does not pump, a) Incorrect electrical connection.
pump performance is
poor, or pump does
b) Incorrect direction of rotation.
not suck.
c) Too little liquid in the pump housing.
d) Air cannot escape.
e) Suction head too large.*
f)
g) Air sucked in through a defective seal.
h) Pump sucks air because of too little liquid.
2. Motor-protective a) Pump blocked.
circuit breaker trips.
b) Pump cannot run as the pump housing is
Motor is overloaded.
c) The density or viscosity of the pumped liquid
d) Motor-protective circuit breaker not correctly
e) Motor running on two phases of three-phase
3. Pump too noisy. a) Suction head too large.*
Pump does not run
smoothly and vibrates.
b) Air in the suction pipe or pump.
c) Pump sucks air because of too little liquid.
d) Impeller is out of balance
e) Internal parts are worn.
f)
g) Defective bearings.
h) Bearings greased with too little, too much or
i)
j)
k) Foreign body in the pump.
4. Pump or connections a) Pump is stressed by the pipework (causing
leaking. Shaft seal or
stuffing box is leaking.
b) Housing seal and connection seals defective.
c) Shaft seal dirty or stuck.
d) Shaft seal worn.
5. Overtemperature of a) Air in the suction pipe or pump.
pump, bearing bracket
b) Suction head too large.
or motor.
c) Bearings greased with too little, too much or
d) Pump with bearing bracket is stressed by the
e) Motor-protective circuit breaker defective or
* Contact the manufacturer.
10
Pipes clogged or foreign body in the impeller.
stressed by the pipework.
is higher than that stated in the order.*
set.
supply.
(clogged impeller blades).
Pump stressed by the pipework
(causing starting noise).
wrong type of grease.
Motor fan defective.
Rubber element of coupling (power
transmission) defective.
leaking pump housing or connections).
wrong type of grease.
pipework.
not correctly set.
Remedy
Check the electrical connection and correct,
if necessary.
Interchange two phases.
Vent and fill the suction pipe and pump.
Discharge pipe clogged. Open all valves.
Increase the liquid level on the suction side.
Open the isolating valve on the suction side.
Open the pump and remove blockage.
Inspect pipe seals, pump housing seals and shaft
seals. Replace defective seals.
Increase the liquid level on the suction side and keep it
as constant as possible.
Open the pump and remove the blockage.
Install the pump so that it is not stressed by the
pipework. Support the pipes.
If a lower performance than that given is sufficient,
throttle the flow on the suction side. If not, use a larger
motor.
Check the setting. Replace the motor-protective circuit
breaker, if defective.
Check the electrical connection. Replace the fuse,
if defective.
Increase the liquid level on the suction side.
Completely open the isolating valve on the suction side.
Vent and fill the suction pipe and pump.
Increase the liquid level on the suction side and keep it
as constant as possible.
Clean and check the impeller.
Replace defective parts.
Install the pump so that it is not stressed by the
pipework. Support the pipes.
Replace bearings.
Add, remove or replace grease.
Replace the fan.
Replace the rubber element and realign the coupling.
See section 8.3 Aligning versions with bearing
Open and clean the pump.
Install the pump so that it is not stressed. Support the
pipes.
Replace seals.
Check and clean the seal.
Replace the seal.
Vent and fill the suction pipe and pump.
Increase the liquid level on the suction side.
Open the isolating valve on the suction side.
Add, remove or replace grease.
Install the pump so that it is not stressed. Support the
pipes. Check the alignment of the coupling.
Check the setting. Replace the motor-protective circuit
breaker, if necessary.
bracket.