Faults, Causes And Remedies - Wilo COE-2-EMHIL Instrucciones De Instalación Y Funcionamiento

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10. Faults, causes and remedies

Faults
One or two pumps fail to prime
One pump fails to run
No delivery pressure
Contactor tripping too frequent, starting
frequency too high
Tripping frequency of dry running
safety too high
Operating automatism device defective
10
Causes
Air leak at suction
Foot-valve strainer not tight or obstruc-
ted
Large losses of head at suction
Public water pressure too low or zero
Suction head too high
Suction piping obstructed or valve on
suction manifold closed
Thermal relay tripped
Magnetic circuit breaker tripped
Pump shaft blocked
Winding fault
Flow higher than booster capabilities
One or two pumps not primed
Public water pressure lower than the
minimum pressure planned
Pumps turn in the reserve direction
A pump is obstructed by particles
Required pressure wrong set
Installation capacity too low
No air inside the tank
Setting of dry running pressure switch-
too high
Drop of the public water supply pressure
when starting the pumps
Wires disconnected
Remedies
Check tightness of all suction pipe con-
nections.
Check if the tank suction strainer is
covered with water
Check tightness of the valve, replace it if
necessary
Calculate the losses of head and make
sure they are compatible with the pump
NSPH
If it recurs, it is recommended to use a tank
Be sure that the minimum water level of
the tank is compatible with the NPSH of
the pumps
Check valve opening and clean the
piping if necessary
The pump "fault" indicator on the control
box must be lit. Check the setting of the
current
Switch it again. If tripping recurs, check
the output current of the motor concer-
ned. If this current is much higher than
the one mentioned on the motor type
plate, the circuit breaker is defective and
shall be replaced
Switch off the electric supply of the con-
trol box and then check the shaft turns
freely. If it is blocked, dismantle the
pump
Disconnect the terminal block of the
motor concerned. Check the network at
the terminals and the stator insulation.
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 compa-
ny or replace the booster.
Contact us
Cross 2 supply wires at the motor termi-
nal blocks
Have the pump dismantled and cleaned
Reset it
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
Check all connections to the terminal
block of the control box
WILO SE 04/2013