York YDAJ87HU7, Руководство пользователя, Страница: 84 / 100

YORK INTERNATIONAL
84
NOTE: Any inductive devices (contactor/relay coil) con-
nected to these contacts must be suppressed
with YORK P/N 031-00808 supplied by others.
Otherwise, nuisance faults may occur.
EVAPORATOR WATER PUMP CONTACT OPTION
This option provides a “dry” contact in the Master Panel
which can be used to turn on the evaporator water pump.
The contact will be closed by the micro before the mi-
cro brings a compressor on. The micro will not bring a
compressor on until a “RUN PERMISSIVE” signal is
established by a flow switch contact closure. If no daily
schedule is set (all times = 00.00), the evaporator wa-
ter pump contact will transition as soon as a System
Switch on the Microprocessor Board is placed in the
ON position.
If a daily schedule is programmed, the evaporator wa-
ter pump contacts will transition when the daily sched-
ule dictates.
If MANUAL OVERRIDE is selected, the evaporator wa-
ter pump contacts will immediately transition.
Connections to this contact can be made on Terminals
25 and 26 of TB1 in the power panel. The location of
these terminals is shown in Fig. 38.
If a power failure occurs which shuts the entire chiller
down, the contacts will not be allowed to close again
until 30 seconds after power is restored. This prevents
rapid cycling of the chilled water pump.
FIG. 47 – EVAPORATOR WATER PUMP CONTACT
CONNECTION POINT (
MASTER PANEL ONLY
)
LD01950
This option utilizes a second Relay Output Board and
associated wiring. The part number for the Field
Mounted Pump Control Kit is 471-01232-101. This kit
is not required if a second Relay Output Board is al-
ready installed in the Master Panel.
NOTE: Any inductive devices (contactor/relay coil) con-
nected to these contacts must be suppressed
with YORK P/N 031-00808 supplied by others.
Otherwise, nuisance faults may occur.
0°F LOW AMBIENT OPTION
The standard chiller is designed to operate in an ambi-
ent of 25°F or higher. If it is necessary to operate the
chiller in an ambient between 0° and 25°F, the chiller
should be purchased with the factory installed Low Am-
bient Option.
NOTE: Occasional operation below 0°F is normally pos-
sible. In these cases a low suction pressure
shutdown may sometimes occur, but can usu-
ally be tolerated.
Two kits, one for both the Master and Slave Control
Panel, are required.
Operation
The fundamental purpose of the Low Ambient Option
is to reduce the capacity of the condenser when the
ambient temperature is in the 0° to 25°F range. This
assures that adequate discharge pressures can be
maintained at low temperatures which will eliminate low
suction pressure faults.
Operation at low ambients is accomplished by cycling
fans according to discharge pressure. This requires the
addition of discharge pressure transducers which al-
lows the microprocessor to add two additional steps of
control to the standard fan control scheme. Fans are
now allowed to cycle completely off and two fans on
each system are permitted to run in the reverse direc-
tion. This reduces the capacity of the condenser as re-
quired. Reverse rotation of the fans is accomplished by
the addition of reversing contactors.
Components
The Low Ambient Option consists of 6 kits; (2) 371-
01232-161 Low Ambient Kits, a 471-01232-131 Dis-
charge Pressure Readout Kit for the Master Module, a
471-01232-136 Discharge Pressure Readout Kit for the
Slave Module, and also (2) 471-01232-101 Relay Board
Kits. The Relay Board Kit(s) is not required if two Relay
Boards are already present in a panel.