Capacity Control Setpoints Screen 1 - York YST Operation Manual

SECTION 2 - OPTIVIEW CONTROL CENTER INTRODUCTION

CapaCiTY ConTrol SeTpoinTS SCreen 1

noTe: OptiView Control Center Screens shown may NOT represent the exact screens according to the software version utilized.
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figure 26 - CapaCiTY ConTrol SeTpoinTS SCreen 1
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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 referenced. All setpoints require a login access
level of Service or higher.
prograMMable
hgvraT – hot gas valve ratio bypass
Screen: Capacity Controls
Range: 0-20 %
This is only used if MSSP7-Speed Control Mode is
set at Fixed. It is used to establish a minimum vane
position above the calculated anti-surge value to pro-
vide greater stability at very low system pressure dif-
ferentials when the minimum vane position calculation
would normally be 0%. Therefore, if the vane signal is
stopped at 5% and the capacity control signal continues
to decrease, the output of the Hot Gas Ratio Calcula-
tion will increase from 0-100% as the control signal
decreases from 5-0% to fully open the Hot Gas Bypass
Valve if required.
74
Default: 5 %
lCvM – Subcooler level valve Minimum
position
Screen: PID Setup Screen 1
Range: 5-100 %
This is used to prevent the Subcooler Level Controller
output (CV) from closing the level control valve too far
while operating in the event of a low refrigerant charge
or level sensor malfunction. The output of the level
controller PID logic will never be allowed to decrease
below this value while the unit is operating.
MSSp1 – Capacity ratchet Mode hgv
reselection
Range: 0-5 %
This is only used if MSSP7-Speed Control Mode is set
at Variable and should rarely need adjustment. While
the Capacity Ratchet Selector is in the Hot Gas mode,
the logic waits until either the capacity control or anti-
surge signal has changed the hot gas valve control sig-
nal more than this value before it re-evaluates whether
the mode control needs to be changed to PRV. How-
ever, if the HGV control signal is at 0% when loading,
the mode is changed immediately to PRV.
FORM 160.67-O1
ISSUE DATE: 4/1/2015
LD09269
Default: 30 %
Screen: Capacity Controls
Default: 3 %
JOHNSON CONTROLS