Fault Finding - Grundfos NBS Serie Notice D'installation Et De Fonctionnement

10. Fault finding

DANGER
Electric shock
Death or serious personal injury
‐
Before removing the terminal box cover and before
removing or dismantling the pump, make sure that the
power supply has been switched off and that it cannot
be accidentally switched on again. Use logout-tagout if
available.
WARNING
Escaping liquid
Death or serious personal injury
‐
Pay attention to the orientation of the vent hole to
ensure that the escaping liquid does not cause
personal injury or damage to the motor or other
components.
‐
In hot-liquid installations, pay special attention to the
risk of personal injury caused by scalding hot liquid.
‐
In cold-liquid installations, pay special attention to the
risk of personal injury caused by cold liquid.
Fault Cause
a) The electrical connection is wrong, for
instance two phases.
b) The direction of rotation is wrong.
c) There is air in inlet pipe.
d) The counterpressure is too high.
1. The pump delivers no or
too little liquid.
e) The inlet pressure is too low.
f) The inlet pipe or impeller is blocked by
debris.
g) The pump draws in air due to a defective
seal.
h) The pump draws in air due to low liquid
level.
a)The pump is blocked by debris.
b) The pump is running above rated duty
point.
c) The density or viscosity of the liquid is
higher than specified upon order.
2. The motor-protective circuit
breaker has tripped because
d) The motor-protective circuit breaker
the motor is overloaded.
overload setting is incorrect.
e)The motor runs on two phases.
f) The motor may be faulty
CAUTION
Cold surfaceor Hot surface
Minor or moderate personal injury
‐
When pumping hot or cold liquids, make sure that no
one can accidentally come into contact with hot or cold
surfaces.
Remedy
1. Check the electrical connection.
2. Remedy, if necessary.
• Interchange two phases of the power supply.
• Vent the inlet pipe or the pump.
1. Set the duty point according to the flow and head that the
pump is selected for.
2. Check the system for debris.
3. Clean the system, if necessary.
• Increase the liquid level on the inlet side.
• Open the isolating valve in the inlet pipe.
• Make sure that all the conditions in section Pipes are
complied with.
• Clean the inlet pipe or pump.
1. Check the pipeline seals, pump housing gaskets and shaft
seals.
2. Replace gaskets and seals, if necessary.
1. Increase the liquid level on the inlet side.
2. Keep the liquid level as constant as possible.
• Clean the pump.
• Set the duty point according to the flow and head that the
pump is selected for.
• If less flow is sufficient, reduce the flow on the outlet side.
• If less flow is insufficient, fit a more powerful motor.
1. Check the setting of the motor-protective circuit breaker.
2. Adjust the setting if necessary.
1. Check the electrical connection.
2. Replace the fuse, if defective.
1. Check the motor.
2. Replace the motor if necessary.
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