Capacity Control Setpoints Screen 2; Figure 27 - Capacity Control Setpoints Screen 2 - York YST Operation Manual

FORM 160.67-O1
ISSUE DATE: 4/1/2015

CapaCiTY ConTrol SeTpoinTS SCreen 2

noTe: OptiView Control Center Screens shown may NOT represent the exact screens according to the software version utilized.
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figure 27 - CapaCiTY ConTrol SeTpoinTS SCreen 2

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This screen allows programming of various parameters
pertinent to the operation of the capacity controls other
than tuning parameters of the PID controllers. To view
the results of a setpoint change, the applicable Screen
name is also referenced. All setpoints require a login
access level of Service or higher. Service Technicians
refer to YORK Service Manual 160.67-M3 for detailed
description of operation.
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prvM – prv Minimum open position
Screen: Capacity Controls
Range: 0-100 %
This is used to provide a minimum opening of the com-
pressor pre-rotation vanes during startup. On startup,
when the ramp up to rated speed has commenced, this
PRV Ramp and the PRV control signal is set at this
value. While the turbine speed is stabilizing and the hot
gas valve is closing, the vanes are opened to this value
to provide additional gas flow through the compressor.
After the stabilization delay has elapsed, the PRV con-
trol signal will begin increasing from this value at the
RRSP8-PRV Ramp Rate. If the Leaving Chilled Liquid
Temperature Controller becomes Active, it begins con-
trolling at the present PRV control signal. LSR3 will
then select the lower of the capacity control signal and
JOHNSON CONTROLS
Default: 10 %
SECTION 2 - OPTIVIEW CONTROL CENTER INTRODUCTION
the PRV Ramp output in order to maintain the leaving
chilled liquid temperature at setpoint.
Subcooler Zone Transition Time
Screen: Condenser
Range: 1-60 Sec. Default: 5 Sec.
When transitioning from Zone 2 to Zone 1, the error
(difference between the measured subcooler level and
the Subcooler Level Controller setpoint) must stay
below the threshold Subcooler Zone Transition Delta
setpoint continuously for this amount of time before
the PID parameters are switched.
Subcooler Zone Transition delta
Screen: Condenser
Range: 1-20% Default: 9%
This subcooler level error (difference between the
measured subcooler level and the Subcooler Level
Controller setpoint) must be greater than this value to
initiate the transition from Zone 1 to Zone 2 control.
When transitioning fron Zone 2 to Zone 1, the error
must stay below this value continously for longer than
the Subcooler Zone Transition Time Setpoint before
the PID parameters are switched.
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