Tecnoware Power Systems
EVO STAR 10-50
18
3.4
CONNECTING THE U.P.S. TO THE MAINS SUPPLY
CAUTION!: ALL CONNECTING PROCEDURES DESCRIBED IN THIS
CHAPTER MUST BE CARRIED OUT BY AUTHORIZED ELECTRICIANS OR BY
QUALIFIED TECHNICIANS.
CAUTION!: THE U.P.S. NEED A NEUTRAL WIRE. THE SYSTEM CANNOT
WORK WITHOUT IT.
3.4.1
COMPATIBILITY WITH THE POWER SUPPLY
The parallel connection to the public mains is normally allowed, as the U.P.S. is comparable
to a passive charge. The mains supply must supply a higher power than the U.P.S rated power
as it has to take into account several factors, such as:
1.
Power absorbed by the output charge on the uninterruptible power supply
2.
System efficiency (see chart 15)
3.
Power needed to charge the batteries
4.
Input harmonic distortion
If you know the amount of power needed by the connected electrical equipment and you
can evaluate the probable expansion margins it is possible to make a first rough estimate of
the power required. As for the power absorbed by the batteries while charging, you can easily
work out the power required by multiplying 436 times 1/10 of the total battery capacity (E.g.:
For a 40A/h battery space, the power needed to charge the battery will be: 436 X (40 / 10) =
1,744 kW). As for input harmonic distortion please remember that for the power supply the
uninterruptible power supply is to be considered as a non-linear load, which generates
harmonic frequency currents multiples of (50/60 Hz). In function of the line impedance this
creates an harmonic voltage distortion. This latter value (total harmonic voltage distortion)
must not exceed the specific environment reference parameters. There are several ways of
reducing this parameter: by increasing the power supply, the section of power supplies cables
or by choosing an interruptible power supply with specific features (twelve-phase input, with
filter).