York YST Operation Manual page 23

FORM 160.67-O1
ISSUE DATE: 4/1/2015
will close to the calculated anti-surge minimum vane
position. While the vanes are closing and the head is
decreasing, the speed will continue to ramp down to
the lower calculated anti-surge minimum speed. When
the PRV position feedback signal is equal to the cal-
culated anti-surge minimum vane position, the hot gas
valve will begin opening. While the hot gas valve is
opening and the head is decreasing, the speed will con-
tinue to ramp down to the lower calculated anti-surge
minimum speed and the vanes will continue to close to
the lower calculated anti-surge minimum.
When the MSSP7-Speed Control Mode on Capacity
Control Setpoints Screen 1 is set for Fixed, the unload-
ing sequence begins with the vanes and proceeds to the
hot gas valve as described above.
The chiller will be shutdown when the hot gas valve
signal has increased to 95% (if HGV is Enabled) or
the Soft Shutdown logic has been unloading the chiller
longer than the TDSP9-Soft Shutdown Rampdown
Timeout minutes entered on the Time Setpoints Screen
(if HGV is Disabled).
While the chiller is unloading, if a LOCAL STOP
is initiated with the Start/Stop control switch or any
faults other than LEAVING CHILLED LIQUID-LOW
TEMPERATURE, REMOTE STOP, or SYSTEM CY-
CLING – CONTACTS OPEN occur, the chiller will
shutdown immediately and SYSTEM COASTDOWN
is displayed.
To restart the chiller after an operator initiated Soft
Shutdown, the Start/Stop control switch must be placed
in the Stop/Reset position (O) and then the Start posi-
tion (◄).
navigaTion
System
Used to provide additional refrigeration system infor-
mation.
evaporator
A detailed view of all evaporator parameters, including
the programmable Leaving Chilled Liquid Setpoints.
JOHNSON CONTROLS
SECTION 2 - OPTIVIEW CONTROL CENTER INTRODUCTION
Condenser
A detailed view of all condenser parameters, including
control of the liquid level functions.
Compressor
A detailed view of all the compressor parameters. This
includes pre-rotation vane position, Hot Gas Bypass
Valve position (Control Output Signal), Proximity
Probe calibration, and PRV calibration.
Steam System
Access Level Required: VIEW
A detailed view of all steam parameters and status of
turbine and steam control devices. It is also the gate-
way to the screens showing details of the turbine lubri-
cation system, steam condenser hotwell level control
system, condensate pump and vacuum pump controls.
Capacity Controls
Access Level Required: VIEW
A detailed view of the capacity control system includ-
ing various override and anti-surge control setpoints
and parameters. It is also the gateway to screens for
entering the tuning parameters of the various PID con-
trollers and other setpoints pertinent to the operation of
the capacity controls. The Auto/Manual Screen is also
accessible from this screen.
Setpoints
This screen provides a single location to program the
most common system setpoints. It is also the gateway
to many of the general system setup parameters such as
Date/Time, Display Units, Printer Setup, etc. System
alarm shutdown setpoints and configuration screens
are also accessed from this screen.
history
This screen provides access to a snapshot of system
data at each of the last 10 shutdown conditions.
2
23