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Electric submersible pumps for sewage
5.3.2 THREE-PHASE ELECTRIC PUMPS
Protection carried out by end user through a control panel in
compliance with characteristics reported at par. 5.3 and able to
assure a reliable lasting running.
GB
Series DIG only are equipped with thermal and control switch
with automatic restarting protecting winding against sudden and
temporary overheating.
Starting equipment, when necessary, must be in compliance with
regulations and rules in force.
The following protection devices by care of installer assure more
safety both for the users and for the electric pump:
- Main switch with suitable sized fuses
- Contactor with thermal realy properly dimensioned to motor power
- Low level device against dry running by floating switch or electrodes
- Minimum voltage relay against phase failure (optional)
- Ammeter, Voltmeter and frequency-meter (optional)
Electric connection scheme for three-phase electric pumps, fig. 9-10-11
5.3.3 ELECTRIC CABLE
In case it should be necessary to extend the length of the electric cable
verify the good quality and the correct section in relation with the length
and the motor power.
The connection must be executed by care of skilled personnel and with
materials that guarantee a perfect insulation of conductors, tightness and
impermeableness lasting in time.
The eventual replacement of electric cable must be carried out by skilled
personnel using electric cable H07RN-F. The cable is suitable for
connection type M according to normatives EN-ì 60335-1 (CEI 61-50).
5.3.4 CHECKING THE ROTATION DIRECTION
(THREE-PHASE ELECTRIC PUMP)
The single phase electric pump rotates always in the correct direction.
In case of wrong rotation direction stop immediately the electric pump and inform
the distributor or the Technical office.
Check the exact rotation direction of three-phase electric pumps proceeding as
follows:
- Slightly tilt the pump to one side or hang it from a lifting means;
- Start the electric pump for a few seconds, making sure that the kick-back
- The correct direction is indicated by harrows on the electric pump cover and
If the rotation direction is wrong, disconnect the power supply and reconnect the
electric pump to the main by switching two of the three phases with each other.
The rotation direction must be checked again every time the electric pump is
electrically disconnected or an intervention is necessary in case of phase failure.
Attention ! The running on wrong rotation direction causes an overload to the
motor and heavy damages to the electric pump.
5.3.5 ELECTRIC PUMP PROTECTIONS
In special working conditions and on demand, the electric pumps series
FEKA - FEKA RC can be supplied with bimetallic thermal probles in the
motor winding and with sensor probes assuring protection against water
ingress into oil chamber.
30
Use and maintenance instructions
does not become a danger hazard;
pump body. If the kick-back has been anticlockwise viewing the electric pump
from above, then the rotation direction is correct (fig.12)
Star connection
Delta connection
Fig. 10
Connection scheme for direct starting
L1
L2
L3
FU1
K1
K3
1 3
1 3
5
2
4
6
2
4
U1 V1 W1
W1 U1 V1
U1
W2
V1
U2
W1
V2
Fig. 11
Connection scheme
for star-delta starting
Reaction
Fig. 12
Oil and thermal probe
control relay
Thermal
probe
Oil
probe
Pump control switch
Wire numeration
Fig. 13
Thermal probe connection
K2
5
1 3
5
6
2
4
6
Electric supply
50-60 Hz
24V AC
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