Grundfos NB Installation And Operating Instructions Manual page 39

Fault
5. The temperature in the pump or
motor is too high.
Related information
5.5.1 Pipe installation
6.5 Frequency converter operation
Cause
a) There is air in the inlet pipe or
pump.
b) The inlet pressure is too low.
c) The bearings are lubricated with
too little, too much or unsuitable
lubricant.
d) The axial pressure is too high.
e) The motor-protective circuit
breaker is defective or the setting is
incorrect.
f) The motor is overloaded.
Remedy
Vent the inlet pipe or the pump and
replenish.
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.
Replenish, reduce or replace the
lubricant.
Check the relief holes of the
impeller and the lock rings on the
inlet side.
Check the setting of the motor-
protective circuit breaker and
replace, if necessary.
Reduce the flow rate.
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