DAB NKV Instructions Pour L'installation Et La Maintenance page 25

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