York YST Operation Manual page 80

SECTION 2 - OPTIVIEW CONTROL CENTER INTRODUCTION
local leaving Chilled liquid Temperature -
Setpoint
Access Level Required: OPERATOR
This value allows the user to define the Leaving
Chilled Liquid Temperature that is to be maintained by
the chiller. It is programmable over the range of 38.0°F
to 70.0°F (water) or 10.0°F to 70.0°F (brine). If Smart
Freeze is enabled, the range is 36.0°F to 70.0°F (wa-
ter). A remote device can provide an analog signal (0-
20 mA, 4-20 mA, 0-10VDC or 2-10VDC) in Analog
Remote mode, or PWM signal in Digital Remote mode
that changes the setpoint by creating an offset above
the operator programmed BASE Leaving Chilled
Liquid Temperature setpoint. This offset may be de-
fined up to 10.0°F or 20.0°F above the BASE setpoint
(see the Remote Leaving Chilled Liquid Temperature
Setpoint Range description above). Additionally, Mi-
croGateway (in ISN Remote mode) can define the
setpoint through a serial data stream. In this case, the
incoming setpoint is not an offset that is applied to the
locally programmed BASE setpoint value, but rather is
the setpoint value itself.
leaving Chilled liquid Temperature
Cycling offset - Shutdown
Access Level Required: OPERATOR
This value allows the user to specify the Leaving Chilled
Liquid Temperature at which the chiller will shut down
on a LEAVINg CHILLED LIQUID – LOW TEM-
PERATURE cycling shutdown. This is done by defin-
ing an offset below the Leaving Chilled Liquid Tem-
perature setpoint. It is programmable over a range of
1°F to 64°F below the setpoint, to a minimum cutout of
36°F (water), 34°F (water with Smart Freeze enabled)
or 6°F (brine). It establishes the minimum allowed
temperature for the Leaving Chilled Liquid Tempera-
ture and prevents over-cooling of the building. Any-
time the Leaving Chilled Liquid Temperature setpoint
is increased, the shutdown threshold is 36.0°F (water)
or 6.0°F (brine) for the next ten (10) minutes. If Smart
Freeze is enabled, the threshold is 34.0°F for the next
10 minutes. After ten (10) minutes have elapsed, the
shutdown threshold becomes the programmed setpoint
value.
leaving Chilled liquid Temperature Cycling
offset - restart
Access Level Required: OPERATOR
This value allows the user to specify the Leaving
Chilled Liquid Temperature at which the chiller will
80
restart after a shutdown on a LEAVINg CHILLED
LIQUID – LOW TEMPERATURE cycling shut-
down. This is done by defining an offset above the
Leaving Chilled Liquid Temperature setpoint. It is
programmable over a range of 0°F to 70°F above the
setpoint, to a maximum restart value of 80°F. The
chiller will automatically restart when this temperature
is reached. This setpoint can be used to reduce chiller
cycling by delaying the chiller restart until the cooling
load has increased.
remote analog input range
Access Level Required: OPERATOR
This setpoint defines, for the Control center, the re-
mote signal range applied for remote reset of the Leav-
ing Chilled Liquid temperature Setpoint and Current
Limit Setpoint in ANALOG remote mode. If the re-
mote signal is 0-10VDC or 0-20mA, this setpoint must
be programmed for 0-10VDC. If the remote signal
is 2-10VDC or 4-20mA, this setpoint must be pro-
grammed for 2-10VDC.
print
Access Level Required: VIEW
Generates Setpoints print report.
navigaTion
home
Access Level Required: VIEW
Causes an instant return to the Home Screen.
Setup
Access Level Required: VIEW
Moves to the sub-screen allowing setup of general sys-
tem parameters.
alarm/Shutdown Setpoints
Access Level Required: VIEW
Moves to the sub-screen displaying the alarm and shut-
down setpoints for safety logic associated with the tur-
bine and steam condenser.
Configuration
Access Level Required: VIEW
Moves to the subscreen displaying the setup of param-
eters associated with the turbine and steam condenser
operation, optional equipment and the configuration of
optional analog inputs and outputs.
FORM 160.67-O1
ISSUE DATE: 4/1/2015
JOHNSON CONTROLS