WDE
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EN/36B/08.2018 © STULZ SpA – all rights reserved
6.3. Electric connections
DANGER
It is absolutely necessary, before making any connections, to check the supply voltage with a
tester. The voltage that is measured must correspond with the voltage indicated on the unit
label.
The installer must install, upstream from the unit, an isolating switch with fuse and capacity
as specified on the label in order to permit maintenance on the machine with total absence of
electricity.
The ON-OFF key on the C2020 keypad (if present) is only used to put the unit on stand-
by. It must not be considered to be a safety component permitting maintenance on the unit.
Maintenance must only be carried out after having isolated the power supply to the unit (see
previous note).
All electric connections and wiring must be done exclusively by authorized technical personnel.
The system must be equipped with an efficient ground connection.
The electric connection to the climate-control system must comply with the following regulations:
Machine safety directive (2006/42/CE)
Low voltage directive (2006/95/CE)
Electromagnetic compatibility directive (2004/108/CE)
National mechanical and electric systems regulations
• Check power supply voltage and frequency.
• Check that these values are compatible with those of the unit (shown in its name-plate).
• Cut off every power supply line before working on the unit.
• Section of power supply cables must be selected in accordance to their length, kind of power
supply and the current absorbed by the unit, as prescribed by current regulations. These cables
must comply with currently applicable standards. In any case we recommend using shielded
cables unless the installer carries out, at his expense, tests that demonstrate that shielding is not
necessary.
• Check that the power cables are installed at an adequate distance from alarm, communication and
monitoring cables.
• On the main power supply line, install a disconnect switch (in overvoltage category III), please refer
to the electric diagram on part 2 manual. Size of main switch must be determined according to the
maximum current consumption of the components (st options). Current absorption data
are in the technical data sheets.
• Do the same on emergency 48VDC power supply line, if present.
• Verify carefully the polarities of DC power supply, according to the wiring diagram.
• For 3-phase scroll compressors: take care of correct phase sequence after the connection
of the main power supply. The sequence is important for the correct sense of rotation of the
3-phase scroll compressor. A loud noise coming from the compressor means it is turning in the
wrong direction. If this continues for a few hours, it will overheat and irreparably damage the
compressor. Correct compressor operation can be easily checked by measuring the temperature
at the condenser outlet. If this temperature is noticeably higher than the external temperature, the
compressors is working correctly. Otherwise, the compressor is turning in the wrong direction and
the phase sequence must be changed.
