Wilo COHe MHI Série Notice De Montage page 22

ONE PUMP FAILS TO RUN
NO DELIVERY PRESSURE
RANDOM OPERATING,
STARTING FREQUENCY
TOO HIGH
TRIPPING FREQUENCY OF
DRY RUNNING SAFETY
TOO HIGH
AUTOMATISM IS NOT
WORKING PROPERLY
p. 22
closed
Thermal relay tripped
Magnetic circuit breaker
defective
Pump shaft blocked
Winding fault
Flow higher than booster
capabilities
One or two pumps are no
more primed
Public water pressure lower
than the minimum pressure
planned
A pump is obstructed by
particles
Voltage of the motors too
low:
Pressure transmitter
defective
Installation capacity too low
No air inside the tank or
under-inflation
Setting of dry running
pressure switch too high
Drop of the public water
supply pressure when
starting the pumps
Control box or cabinet
defective
Wires disconnected
Transmitter defective
The pump "fault" indicator on the control box
must be lit.
Check the setting of the thermal relay and
reset it.
Check the direction of rotation, the coupling
or the current requirement of the motor
concerned
Check that the motor phases are not in
short-circuit between them. Replace the
motor if necessary.
Reset the circuit breaker.
Switch off the electric supply of the control
box and then check the shaft turns freely, if it
is blocked, dismantle the pump
Disconnect the terminal board of the terminal
block and check the stator insulation to
earth. Replace the motor if necessary.
Plan to replace the booster by a more
adequate one (do not forget to contact us in
any case).
Check that the suction strainer does not let
air in or the tank filling point is too close from
the strainer.
Contact the public water supply company or
replace the booster. Contact us
Have the pump dismantled and cleaned
Check the voltage on motor terminals
Check the setting: transmitter not stable,
replace it if necessary
Add a tank.
Pressurize the tank or replace the bladder.
Set the pressure switch correctly.
Set the dry running pressure switch to the
minimum value. If it recurs, the public water
mains is inadequate; check the pressure
with the pressure gauge when starting the
pumps or contact the public water mains
service.
See starting instruction of the control box or
cabinet.
Check all connections to the terminal block
of the control box.
Check the contacts, change the transmitter
concerned if necessary
4227862 ed.04