ENGLISH
21
Fault Check (possible cause) Remedy
− Verify that supply voltage is at an
acceptable valve.
− Check whether any moving parts
are scraping against fixed parts.
Eliminate the cause of the scraping.
The motor turns with difficulty.
− Check the state of the bearings.
Change any worn bearings.
− Check that all the phases are
present.
Restore the missing phase.
− Look for possible open or dirty
contacts in the protection.
Change or clean the component
concerned.
The (external) motor protection
trips immediately after starting.
− Look for possible faulty insulation
of the motor, checking the phase
resistance and insulation to earth.
Change the motor casing with the
stator or reset any cables
discharging to earth.
− Ensure that the environment
temperature is not too high.
Provide suitable ventilation in the
environment where the pump is
installed.
− Check the calibration of the
protection.
Calibrate at a current value suitable
for the motor absorption at full load.
− Check the state of the bearings.
Change any worn bearings.
The motor protection trips too
frequently.
− Check the motor rotation speed.
− Check priming.
− On three-phase motors, check that
the direction of rotation is correct.
Invert the connection of two supply
wires.
− Difference in suction level too high.
− The diameter of the intake pipe is
insufficient or the horizontal stretch
is too long.
Replace the intake pipe with one
with a larger diameter.
The pump does not deliver.
− Foot valve or intake pipe blocked.
Clean the foot valve and the intake
pipe.
− The intake pipe or the foot valve is
taking in air.
Check the suction pipe, repeat the
priming operations.
The pump does not prime.
− Check the slope of the suction
pipe.
Correct the inclination of the intake
pipe.
− Foot valve or impeller blocked.
Remove clog. Replace the impeller
if weared down.
− The diameter of the intake pipe is
insufficient.
Replace the pipe with one with a
larger diameter.
The pump supplies insufficient flow.
− Check that the direction of rotation
is correct.
Invert the connection of two supply
wires.
− Intake pressure too low.
The pump flow rate is not constant.
− Intake pipe or pump partly blocked
by impurities.
Remove clog.
− Leakage in the intake pipe.
The pump turns in the opposite
direction when switching off.
− Foot valve or check valve faulty or
blocked in partly open position.
Repair or replace the faulty valve.
− Check that the pump and/or the
pipes are firmly anchored.
− There is cavitation in the pump.
Reduce the intake height or check
for load losses.
− The pump is running above its
plate characteristics.
Reduce the flow rate.
The pump vibrates and operates
noisily.
− The pump is not turning freely.
Check the state of wear of the
bearings.
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