Viessmann VITOCAL 242-G Installation And Service Instructions Manual page 75

Power supply
(cont.)
Main isolator requirements (if necessary)
If a main isolator is set, it must isolate
the power circuit with at least 3 mm
contact separation.
General information regarding the power supply
The power supply is separated into 3
areas:
Control unit feed (electronics)
Instantaneous heating water heater
feed (main power circuit)
Heat pump compressor feed (main
power circuit)
Subject to heat pump, the equipment
is connected to a 400 V three phase
AC or 230 V single phase AC supply.
The feed for the control unit and the
instantaneous heating water heater is
provided on the main connecting area
X60. The compressor feed comes
from control module X80 (see also
page 55).
The power cables to the main power
circuits must have a suitable cross-
section for the rated current (see spe-
cification from page 222 onwards).
Danger
The absence of component earthing can transfer dangerous body cur-
rents, should an electrical fault occur.
The equipment and the pipework must be connected to the earth bonding
of the house in question.
!
Please note
An incorrect phase sequence can cause damage to the unit.
The power supply to the compressor must have a clockwise rotating
field in the phase sequence that is specified at the terminals.
Installation sequence
If no main isolator is set, all non-
earthed cables must be isolated by
the upstream cable protection switch
with at least 3 mm contact separation.
Protect the power cable to the control
unit with a fuse of max. 16 A.
The power fuses for the compressor
must have Z characteristics.
Note
We recommend making the power
connection for accessories and exter-
nal components to the same fuse,
with at least the same phase as the
control unit.
Connection to the same fuse provides
additional safety when the power is
switched off. However, please pay
attention to the power consumption of
the consumers that are connected
when doing this (control unit feed fuse
protection max. 16 A).
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