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

SECTION 4 - INSTALLATION
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
troubleshooting this type of equipment.

POWER WIRING

All electrical wiring should be carried out in accor-
dance 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 via the same cable entry.
All sources of supply to the unit must be
taken via a common point of isolation (not
supplied by Johnson Controls).
Copper power wiring only should 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 assure moist
air from the building cannot enter the
panel.
46

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 52.
• Connect a suitably sized earth wire to the PE ter-
minal in the panel.

115VAC CONTROL SUPPLY TRANSFORMER

A 3-wire high voltage to 115VAC supply transformer
is standard in the chiller. This transformer is mounted
in the cabinet and steps down the high voltage supply
to 115VAC 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 chill-
er will remove the 115VAC 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 operation 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 115VAC 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 115VAC 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.
FORM 201.28-NM1.1
ISSUE DATE: 1/31/2018
JOHNSON CONTROLS