FORM 160.60-O2 (1004)
25
YORK INTERNATIONAL
2
The Capacity Controls Screen schematically illustrates
the logical operations of chiller capacity control. Sensor
readings are linked with setpoint values and compared.
PID loops, depicted in each box, pass signals through
high or low-pass relay (HSR/LSR) junctions. The relay
makes a simple comparison of two signals and passes
the higher or lower of the two depending on whether
the relay is high or low pass. The PRV CONTROL
box links the PID signals to system logic in order to
determine the correct sequencing of output signals to
the appropriate actuators.
OVERRIDES
Evaporator Pressure
Displays the current evaporator pressure
Low Pressure Setpoint
Displays the system low evaporator pressure setpoint
Condenser Pressure
Displays the current condenser pressure
High Pressure Setpoint
Displays the system high condenser pressure setpoint
Engine Load
Displays the current engine load
Load Limit
Displays the engine load limit setpoint
Water Jacket Temperature
Displays the current engine water jacket temperature.
Displays the engine water jacket high temperature
setpoint.
HGV Ramp
Displays the hot gas valve ramp rate in percent
HGV
Displays the current hot gas valve position from opened
to closed in percent
PRV Pot
Displays the current position of the pre-rotation vanes
from opened to closed in percent
PRV Target
Displays the control-system intended position of the
pre-rotation vanes
CAPACITY CONTROLS SCREEN
FIG. 17 - CAPACITY CONTROLS SCREEN
LD09891
