15
GB
Electrical equipment.
Make sure that the electric control panel complies with the laws in force in the country of use. Particularly make sure that its
protection class suits the place of installation.
It is advisable to install electrical equipment in a dry, well ventilated place where the temperatures are not extreme
(e.g.
-
20 to +40°C). Failing this, use special versions of the equipment.
WARNING
The contacts of undersized or poor quality electrical equipment are liable to deteriorate quickly. This leads to unbalanced power
being supplied to the motor, which could be damaged as a consequence.
Unless correctly researched and installed, use of Inverters and Soft-starters could impair the safety of the pumping unit. Ask the Calpeda
Technical Office for assistance if the relative difficulties are not known.
Safe operation depends on good quality electrical equipment being installed.
All starting equipment must always be equipped with:
1) main disconnector with a gap of at least 3 mm between its contacts and a device to lock it in the open position;
2) a suitable thermal protector device for the motor with a maximum current input setting no more than 5% higher than the rated current indicated on
the motor's data plate and with a trip time of less than 30 seconds;
3) a suitable magnetic device to protect the cables against short-circuits;
4) a suitable protection device that isolates the power supplier in the case of earth faults in the electric pump;
- the following devices are also recommended -
5) a suitable device to protect against phase loss;
6) a device to protect against dry operation;
7) a voltmeter and an amperometer.
Power supply voltage
.
Permitted variations on supply voltage:
400V ±10% [50Hz]
460V ±10% [60Hz]
For other voltage/frequency values: ±5%
Tolerances on operating features: in compliance with IEC 34-1 International Standards.
Heat probes available upon request.
WARNING
Make sure that the voltage and frequency values with which the motor is supplied correspond to the data on the motor rating plate. Ask
for a special version of the motor if the supply voltage fails to comply with the admissible variations. To prevent voltage dips of more
than 2.5-3% the rated value, make sure that the power supply cable has been sized in relation to its length, the power consumption
of the unit and the air temperature (consult the technical annex of Calpeda's Submersible Electric Pumps catalogue for details about
how to size the cable correctly). The voltage must be sinusoidal, while the system must be three-phase with symmetrical supply.
In accordance with standard CEI 2.3 (IEC 38), the supply voltage in an alternating current motor is considered to be practically
sinusoidal if, when the motor functions at rated load, the waveform is such that the difference between its every instantaneous
value and the corresponding instantaneous value of the fundamental component does not exceed 5% of the amplitude of this latter.
During the temperature-rise test, this difference in amplitude must not exceed 2.5%. The three-phase voltage system is considered
to be symmetric when the negative sequence component does not exceed 1% of the positive sequence component of the voltage
system during a long period of time, or 1.5% for a short period of no more than a few minutes, or if the homopolar component of the
voltage system does not exceed 1% of the positive sequence component.
Direction of rotation.
WARNING
The wrong direction of rotation can damage the motor since the power input and axial thrust of the pump is generally sensibly higher
than forecast.
Find the correct direction of rotation (anti-clockwise for the pump viewed from the discharge side) by means of the following operations:
1) fill the pipe and measure the pressure developed by the electric pump with the slide valve closed;
2) disconnect the mains power supply and invert two of the three phases;
3) repeat the operation from point 1. Maximum pressure shows that the direction of rotation is correct.
If the pump is installed at great depth, the pressure developed during operation in the wrong direction of rotation will not even be sufficient to
overcome the static level.
Phase imbalance.
Check the power input of each phase. Imbalance must not exceed 5%. If higher values are found (which could be caused by the motor but also by
the electricity main), check the power inputs of the other two motor-mains connection combinations, taking care to avoid reversing the
direction of rotation. The best connection will be the one with the least power input difference among the phases. Note that if the highest
power input is always detected on the same phase of the line, the main cause of imbalance will be due to the mains supply.
