7 TROUBLESHOOTING TABLE
Before any intervention, disconnect the pump
from power supply.
If the pump is used for hazardous liquids for
human beings, inform compulsorily the per-
sonnel performing the repairing. In this case,
clean the pump, in order to assure the safety
of the operator.
See table below.
Fault
Cause
Remedy
7.1 The motor does not run when
started.
a) Lack of power supply.
Connect power supply.
b) Blown out fuses.
Replace fuses.
c) Thermal protection tripped.
Restore the thermal protection.
d) Motor defective.
Replace the motor.
7.2 The thermal protection of the
motor starter trips at start.
a) Fault in the contacts of the thermal
switch of the motor starter.
Replace the contacts of the motor
starter.
b) Connection of the cables faulty.
Tighten or replace the cables.
c) Motor wiring faulty.
Replace the motor.
d) Mechanical block of the pump.
Remove the mechanical pump block.
e) Calibration of the thermal relay
too low.
Calibrate the motor starter correctly.
7.3 The thermal protection of the
motor starter trips now and then.
a) Calibration of the thermal relay
too low.
Calibrate the motor starter correctly.
b) Low voltage during the peaks.
Check power supply.
7.4 The flow rate is not constant.
a) Pressure too low during suction
(cavitation).
Check the NPSH of the pump.
b) Suction manifold / pump partially
obstructed by impurities.
Clean the pump or the suction
manifold.
c) The pump sucks air.
Check the suction conditions.
7.5 The pump rotates but does not
supply water.
a) Suction manifold / pump partially
obstructed by impurities.
Clean the pump or the suction
manifold.
b) Bottom valve or check valve
blocked in closed position.
Repair the bottom valve or the check
valve.
c) Leak in the suction manifold.
Repair the suction manifold.
d) Presence of air in the suction
manifold or in the pump.
Check the suction conditions.
e) The motor rotates in wrong
direction.
Change the motor rotation direction.
7.6 The pump vibrates.
a) Anchoring on the plinth faulty.
Verify and completely screw the nuts
of the bolts of the studs.
b) Foreign body obstruct the pump.
Disassemble the pump and clean it.
c) “Hard” rotation of the pump.
Verify that the pump rotates freely
without anomalous hindrances.
d) Electric connection faulty.
Verify the connections of the pump.
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