Electrical Wiring - Midea VC Pro Series Engineering Data

9 Electrical Wiring

9.1 General
Notes for installers
Caution
 All installation and wiring must be carried out by competent and suitably qualified, certified and accredited
professionals and in accordance with all applicable legislation.
 Electrical systems should be grounded in accordance with all applicable legislation.
 Overcurrent circuit breakers and residual-current circuit breakers (ground fault circuit interrupters) should be
used in accordance with all applicable legislation.
 Wiring patterns shown in this data book are general connection guides only and are not intended for, or to
include all details for, any specific installation.
 The refrigerant piping, power wiring and communication wiring are typically run in parallel. However the
communication wiring should not be bound together with the refrigerant piping or power wiring. To prevent
signal interference, the power wiring and communication wiring should not be run in the same conduit. If the
power supply is less than 10A, a separation of at least 300mm between power wiring and communication wiring
conduits should be maintained; if the power supply is in the range 10A to 50A then a separation of at least 500mm
should be maintained.
9.2 Power Supply Wiring
Power supply wiring design and installation should adhere to the following requirements:
 Separate power supplies should be provided for the indoor units and outdoor units.
 Where five or more outdoor units are installed, additional residual current protection (leakage protection) should be
installed as shown in Figure 3-9.1.
 All the indoor units in a system (i.e. all the indoor units connected to the same set of outdoor units) should be tied into
the same power circuit with the same power supply, overcurrent and residual current protection (leakage protection)
and manual switch, as shown in Figure 3-9.2. Do not install separate protectors or manual switches for each indoor
unit. Powering on and shutting down all indoor units in a system should be done simultaneously. The reason for this is
that if an indoor unit that is running were to suddenly power off whilst the other indoor units continued running, the
evaporator of the powered-off unit would freeze since refrigerant would continue flowing to that unit (its expansion
valve would still be open) but its fan would have stopped. The indoor units that remain running would not get sufficient
refrigerant so their performance would suffer. Additionally, liquid refrigerant returning directly to the compressor from
the powered-off unit would cause liquid hammering, potentially damaging the compressor.
 For outdoor unit power wire sizing and circuit breaker sizing, refer to Table 2-6.1 in Part 2, 6 "Electrical Characteristics".
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VC Pro VRF 50/60Hz
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