Power Wiring; Power Supply Wiring; 115 Vac Control Supply Transformer; Control Wiring - York YVAA Installation Operation & Maintenance

Form 201.47-ICOM1
Issue date: 17/11/2022
After power wiring connection, do not
switch on mains power to the unit. Some
internal components are live when the
mains are switched on and this must only
be done by authorized persons familiar
with starting, operating, and trouble-
shooting this type of equipment.

Power wiring

All electrical wiring must be carried out in accordance
with local regulations. Route properly sized cables to
cable entries on the unit.
In accordance with local codes, NEC codes, U.L. and
C.E. standards, it is the responsibility of the user to
install over current protection devices between the
supply conductors and the power supply terminals on
the unit.
To ensure that no eddy currents are set up in the power
panel, the cables forming the 3-phase power supply
must enter using the same cable entry.
All sources of supply to the unit must be
taken using a common point of isolation
(not supplied by Johnson Controls).
Copper power wiring only must be used for supply-
ing power to the chiller. This is recommended to avoid
safety and reliability issues resulting from connection
failure at the power connections to the chiller. Alumi-
num wiring is not recommended due to thermal char-
acteristics that may cause loose terminations result-
ing from the contraction and expansion of the wiring.
Aluminum oxide may also build up at the termination
causing hot spots and eventual failure. If aluminum
wiring is used to supply power to the chiller, AL-CU
compression fittings should be used to transition from
aluminum to copper. This transition should be done in
an external box separate to the power panel. Copper
conductors can then be run from the box to the chiller.
Caulk power and control wiring conduit
entering the power panel to ensure moist
air from the building cannot enter the
panel.
JOHNSON CONTROLS

Power supply wiring

• Units require only one 3-phase supply, plus earth.
• Connect the 3-phase supplies to the circuit breaker
located in the panel See Table 4 on page 45.
• Connect a suitably sized earth wire to the PE ter-
minal in the panel.

115 VAC control supply transformer

A 3-wire high voltage to 115 VAC supply transformer
is standard in the chiller. This transformer is mounted
in the cabinet and steps down the high voltage supply
to 115 VAC to be used by the controls, VSD, Feed and
Drain Valve Controller, valves, solenoids, heaters, and
so on.
The high voltage for the transformer primary is taken
from the chiller input. Fusing is provided for the trans-
former.
Removing high voltage power to the
chiller will remove the 115 VAC supply
voltage to the control panel circuitry
and the evaporator heater mat. In sub-
freezing weather, this could cause serious
damage to the chiller due to evaporator
freeze-up. Do not remove power unless
alternate means are taken to ensure op-
eration of the control panel, evaporator
heater mat, and waterbox heaters.

Control wiring

All control wiring utilizing contact closures to the
control panel terminal block is nominal 115 VAC and
must be run in shielded cable, with the shield grounded
at the panel end only, and run in water tight conduit.
Run shielded cable separately from mains cable to
avoid electrical noise pick-up. Use the control panel
cable entry to avoid the power cables.
Voltage free contacts connected to the panel must be
suitable for 115 VAC 10 mA (gold contacts recommend-
ed). If the voltage free contacts form part of a relay or
contactor, the coil of the device must be suppressed using
a standard R/C suppressor. The above precautions must
be taken to avoid electrical noise, which could cause a
malfunction or damage to the unit and its controls.
SECTION 4 - INSTALLATION
37
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