7
Problem How to check Remedy
5 Protection
trips
too often
6 Shaft
spins
with difficulty
A - Check for obstructions in the motor or the
pump.
B - As in 5D.
C - Check bearings for proper conditions.
A - As in 2B.
B - As in 5D.
C - Replace any faulty bearing.
A - Ascertain whether the protection device is
set to a value lower than the motor full load
requirements.
B - One phase is missing due to faults in
contacts or supply cable.
C - Liquid is viscous or its specific weight is
much higher than that of water.
D - Harsh rubbing occurs between sliding and
stationary parts.
A - Correct setting.
B - Clean and reset contact or
replace supply cable with new
one.
C - Reduce flow rate slightly by
adjusting the delivery sluice
valve accordingly. If this is not
acceptable, instal a more
powerful motor.
D - Remove cause of harsh
rubbing.
8
When stopped,
the pump runs
slightly in reverse
direction
A - Leaks or air locks in suction pipe. A - Correct leaks and read section
“installation”.
7 Pump
vibrates, runs
noisily;
flow rate
is uneven
A - Pump runs beyond rated capacity.
B - Pump or pipework not properly secured.
C - As in 3F.
D - As in 3G.
A - Reduce flow rate.
B - Secure any loose or improperly
secured part.
C - As in 3F.
D - As in 3G.
9
In pressure
boosting
applications the
pump starts and
stops too often
A - Pressure-switch setting is too limited.
B - Leaks in system.
A - Set pressure switch to wider
limits.
B - Eliminate leaks.
10
In pressure
boosting
applications, the
pump does not stop
A -
Max.-pressure setting in pressure switch
is too high.
B -
As in 9B
A - Reduce max-pressure setting
to lower value.
B - As in 9B.
8. Fault finding chart: problems, possible causes and remedies
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