YORK INTERNATIONAL
FORM 160.73-O2 (605)
20
While the chiller is shut down, the orifi ce will be in the
fully open position causing the sensed level to be ap-
prox i mate ly 0%. When the chiller is started, after the
vane motor end switch (VMS) opens when entering
SYSTEM RUN
, if actual level is less than the level
setpoint, a linearly increasing ramp is applied to the
lev el setpoint. This ramp causes the setpoint to go from
the initial refrigerant level (approximately 0%) to the
pro grammed setpoint over a period of 15 minutes.
If the actual level is greater than the setpoint when the
VMS opens, there is no pulldown period, it im me di ate ly
begins to control to the programmed setpoint.
While the chiller is running, the refrigerant level is nor-
mal ly controlled to the level setpoint. However, any time
the vanes fully close (VMS closes), normal level con trol
is terminated, any refrigerant level setpoint pulldown in
effect is cancelled and the outputs to the level control
will be opposite that which is supplied to the vane motor
(i.e., when a close pulse is applied to the vane motor, an
open pulse is applied to the level control, etc.). When the
VMS opens, if the refrigerant level is less than the level
set point, a refrigerant level setpoint pulldown is initiated
as described above. Oth er wise, the level is con trolled to
the programmed set point.
OPTIONAL SERVICE ISOLATION VALVES
If your chiller is equipped with optional service iso la tion
valves on the discharge and liquid line, these valves
must remain open during operation. These valves are
used for isolating the refrigerant charge in either the
evap o ra tor or condenser to allow service access to the
sys tem. A re frig er ant pump-out unit will be required to
iso late the re frig er ant.
Isolation of the refrigerant in this sys-
tem must be per formed by a qualifi ed
service tech ni cian.
OPTIONAL HOT GAS BYPASS
Hot gas bypass is optional and is used to eliminate
com pres sor surge during light load or high head op-
er a tion. The OptiView con trol panel will automatically
mod u late the hot gas valve open and closed as re quired.
Ad just ment of the hot gas control valve must be per-
formed by a qual i fi ed service tech ni cian fol low ing the
Hot Gas Set-up pro ce dure.
Changes in chilled water flow will
re quire re ad just ment of the hot gas
con trol to in sure prop er operation.
OTIVIEW CONTROL CENTER
(See Section 2)
The OptiView Control Center is factory-mounted, wired
and tested. The elec tron ic panel automatically controls
the op er a tion of the unit in meet ing system cool ing re-
quire ments while minimizing en er gy usage. For de tailed
in for ma tion on the Control Center, refer to “Sec tion 2”
of this manual.
SOLID STATE STARTER (Optional)
The Solid State Starter is a reduced voltage starter
that controls and maintains a constant current fl ow to
the motor during start-up. It is mounted on the chiller.
Pow er and control wiring between the starter and chill er
are factory installed. Available for 380-600 volts, the
start er enclosure is NEMA-1 with a hinged access door
with lock and key. Electrical lugs for incoming power
wir ing are provided.
VARIABLE SPEED DRIVE (Optional)
A 460V – 3-Ph – 60/50 Hz Variable Speed Drive can
be factory packaged with the chiller. It is designed to
vary the compressor motor speed and prerotation vane
po si tion by controlling the frequency and voltage of
the elec tri cal power to the motor. Operational informa-
tion is contained in Form 160.00-O1. The control logic
au to mat i cal ly adjusts motor speed and compressor pre-
rotation vane position for maximum part load ef fi cien cy
by an a lyz ing information fed to it by sensors located
through out the chiller.
System Components De scrip tion