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6.3 Motor protector
According to needs the following can be used:
•
A contactor with thermal relay
•
Motor protector magnetothermic switch
In all cases, the thermal relay must be of the 10 or 10A tripping class:
•
Tripping time <8s at 5 times In
•
Sensitivity to phase failure
Set the motor protector at the service current value measured but without exceeding the value
indicated on the motor’s rating plate.
6.4 Using the submersible electropump with a frequency converter (FC)
Note
If the motor is used with an FC follow the instructions in the relative manual.
→
It is recommended to use motors “F” series in PE2+PA.
→
Make sure that motor current, in all working points of the adjustment field, does not
exceed the motor’s rated current indicated on the rating plate.
→
Adjust the FC so as to keep the limit values of the motor’s nominal frequency equivalent
to a min. 35 Hz and max. at the motor’s nominal frequency (50 or 60 Hz).
→
If an FC is used, limit motor voltage peaks to the following values:
max. voltage increase 500 V/
µ
s, max. voltage peak 1000 V.
→
Make sure that the time for the motor to reach rotation from 0 to 35 Hz and slowing down
time from 35 to 0 is no more than one second.
→
When sizing the cables, take the power loss into account due to the additional filters.
→
Make certain that the necessary speed of the water is maintained along the motor also
when using an FC.
6.5 Using the submersible electropump with the soft start device
Note
If the submersible electropump is used with a soft start device follow the instructions in the relative
manual.
→
Set the starting voltage of the soft starter at 55% of the rated voltage; set starting and
stopping time at maximum three seconds.
→
After start up, exclude the soft starter via a contactor.
7 Operating of the electropump
7.1 Rotation direction of the submersible electropump
Damages to the electropump
→ A wrong rotation direction could damage the motor. After having filled the pipe, measure
the pressure developed by the electric pump with the sluice valve closed, disconnect the
electricity supply and switch two of the three phases with each other. Maximum pressure is
an indicator of the correct rotation direction.
→ Too many start up/hour of the electropump cause damages to it. Verify the maximum start
up/hour allowed that can be found in the technical sheet of the motors’ catalogue.
7.2 Starting of the electropump
All the actions described in the previous chapter have been done properly.
→
Start-up the electropump from the control panel switch paying attention that the first
start-up must be accomplished with the isolating sluice valve only partially open. This
will limit the entrainment of any sand or silt to the minimum. If water is turbid, throttle the
sluice valve, checking that the pump delivers not more solid matter than the amount
written in the catalogue (see submersible pump catalogue).
EN
