D–EIMAC01905-23_00EN - 39/53
The power supply to the unit must be set up in such a way that it can be switched on or off independently from that of
other system components and other equipment in general, by means of a general switch.
The electrical connection of the panel must be carried out maintaining the correct sequence of the phases.
Do not apply torque, tension or weight to the main switch terminals. Power line cables must be
supported by appropriate systems.
Simultaneous single and three-phase loads and phase unbalance can cause ground losses of up to 150 mA during normal
unit operation. The unit includes devices that generate higher harmonics, such as an inverter, that can increase ground
losses to much higher values, about 2 A.
The protections for the power supply system must be designed according to the values mentioned above.
A fuse must be present on each phase and, where provided for by the national laws of the country of installation, a leak
detector to earth.
Make sure that the short-circuit current of the system at the installation point is less then the rated short-time withstand
current (Icw); the value of Icw is indicated inside the electrical panel.
The standard equipment has to be use in TN-S earthing system; if your system is different please contact the manufacturer
representative.
Before any electrical connection work to the compressor motor and / or the fans, make sure that the
system is switched off and the main switch of the unit is open. Failure to observe this rule could
result in serious personal injury.
5.4 Cable requirements
The cables connected to the circuit breaker must respect the insulation distance in the air and the surface isolation
distance between the active conductors and the earth, according to IEC 61439-1 table 1 and 2, and to the local national
laws. The cables connected to the main switch must be tightened using a pair of keys and respecting the unified clamping
values, relative to the quality of the screws of the washers and nuts used.
Connect the earth conductor (yellow / green) to the PE ground terminal.
The equipotential protection conductor (earth conductor) must have a section according to table 1 of EN 60204 -1 Point
5.2, shown below.
Table 16- Table 1 of EN60204-1 Point 5.2
Section of the copper phase
conductors feeding the equipment
S [mm
2
]
Minimum cross-section of the external
copper protection conductor
Sp [mm
2
]
S ≤ 16
16 < S ≤ 35
S > 35
In any case, the equipotential protection conductor (earth conductor) must have a cross section of at least 10 mm 2, in
accordance with point 8.2.8 of the same standard.
5.5 Phase unbalance
In a three-phase system, the excessive imbalance between the phases is the cause of the engine overheating. The
maximum permitted voltage unbalance is 3%, calculated as follows:
where:
Vx = phase with greater unbalance
Vm = average of the tensions
Example: the three phases measure 383, 386 and 392 V respectively. The average is:
The unbalance percentage is:
less than the maximum allowed (3%).
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