York YST Operation Manual page 76

SECTION 2 - OPTIVIEW CONTROL CENTER INTRODUCTION
TdSp10 – Temp Control override Transfer
delay
Screen: Capacity Controls
Range: 0-60 Sec
This is used to delay the transfer of the capacity con-
trols back to the Leaving Chilled Liquid Temperature
Controller after the system conditions have returned to
normal and the override controller is no longer control-
ling.
TdSp14 – anti-Surge update delay Time
Screen: Capacity Controls
Range: 0-60 Sec
This is only used if MSSP7-Speed Control Mode is set
at Variable. While the Capacity Ratchet Mode Selector
is in the Hot Gas mode, as the head decreases the speed
may be reduced and the vanes closed further so that
less hot gas is required to maintain the leaving chilled
liquid temperature at setpoint. To maintain maximum
efficiency of operation, the lower calculated minimum
speed (MS%) and minimum vane position (MV%) are
moved into the associated devices every time this time
delay has elapsed. This will allow the hot gas valve to
move closed and reduce steam consumption. When in
the PRV mode and the head decreases, the lower mini-
mum speed (MS%) is moved into the Speed Setpoint
every time this time delay has elapsed. This will allow
the vanes to open further and reduce steam consump-
tion.
TSp3 – hot gas valve Temp Controller Sp diff
Screen: Capacity Controls
Range: 0-4.0 °F
This is only used if MSSP7-Speed Control Mode is set
at Fixed. In some cases, it may be desirable to allow
the vanes to go completely closed which would leave
no signal for the Hot Gas Ratio calculation to control
the hot gas valve. This is the value subtracted from the
present Leaving Chilled Liquid Temperature Setpoint
to determine the setpoint of the HGV Temperature
Controller. This output of this controller increases as
the Leaving Chilled Liquid Temperature decreases be-
low the setpoint to open the Hot Gas Valve and main-
tain the leaving chilled liquid temperature at setpoint.
The response time of the controller is determined by
the tuning entered on the PID Setup Screen 1 for the
Temperature Control when the Select Control key is
set at HGV.
76
Default: 5 Sec
Default: 30 Sec
Default: 1.1 °F
Change Setpoints
Access Level Required: SERVICE
This key enables the field selection cursor. The opera-
tor may then toggle between the programmable data
fields using the Cursor Arrow keys.
navigaTion
page down
Access Level Required: VIEW
Moves to the Capacity Control Setpoints Screen 2.
home
Access Level Required: VIEW
Causes an instant return to the Home Screen.
Capacity Controls
Access Level Required: VIEW
Causes an instant return to the Capacity Controls
Screen.
FORM 160.67-O1
ISSUE DATE: 4/1/2015
JOHNSON CONTROLS