York YST Operation Manual page 22

SECTION 2 - OPTIVIEW CONTROL CENTER INTRODUCTION
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login
Access Level Required: VIEW
The OptiView Panel restricts certain operations based
on password entry by the operator. Three different ac-
cess levels are provided as follows: VIEW: The panel
defaults to the lowest access level which is termed
VIEW. In this mode, the chiller operating values and
setpoints can be observed, but no changes can be made.
OPERATOR: The second access level is termed OP-
ERATOR and will allow the customer to change all
of the setpoints required to operate the chiller system.
The OPERATOR access level reverts to the VIEW
level after 10 continuous minutes without a keypress.
SERVICE: In the event that advanced diagnostics are
necessary, a SERVICE access level has been provid-
ed. Only qualified service personnel utilize this access
level. This level provides advanced control over many
of the chiller functions and allows calibration of many
of the chiller controls. The access levels are listed
above in hierarchical order beginning with the lowest
level and proceeding to the highest level. Users logged
in under higher access levels may perform any actions
permitted by lower access levels.
The OPERATOR access level is accompanied by a
10-minute timeout. After ten (10) successive minutes
without a keypress, the panel will revert to the VIEW
access level. This prevents unauthorized changes to the
chiller if a user was logged in at a higher access level
and failed to logout. Proper procedure requires that
after making necessary setpoint adjustments the user
return to the Home Screen and logout.
logout
Access Level Required: OPERATOR
This key is displayed when a user is logged in at any
level other than VIEW. Pressing it will return the ac-
cess level to VIEW.
print
Access Level Required: VIEW
Use this key to generate a hard-copy report of the
present system status. This provides a snapshot of the
primary operating conditions at the time the key is
pressed. The History page provides enhanced report-
ing capability. (See HISTORY below.)
22
Message Clear
Access Level Required: SERVICE
When certain safety or cycling conditions have been
detected and the chiller has been shutdown, the main
status display of the chiller will continue to display a
message indicating the cause of the shutdown. Using
this key, the message can be cleared once the condi-
tion has been removed. Safety Shutdown Messages
cannot be cleared until 35 seconds after the drive train
has coasted to a stop as detected by the turbine rotating
(speed switch) digital input.
Warning reset
Access Level Required: OPERATOR
Use of this key acknowledges a warning condition and
resets the message display associated with it.
Soft Shutdown
Access Level Required: OPERATOR
This key, available only when the chiller is running,
is used to initiate a controlled shutdown. This will de-
crease the sudden loss of steam load when the chiller
trips, possibly preventing boiler relief valves from lift-
ing.
When the MSSP4-Turbine Start Mode is set for Auto,
when the Soft Shutdown is initiated, the Main Steam
Inlet Valve control output is first decreased (ramped
down at RRSP7 %/second) until it is equal to or less
than the current output to the Governor Valve. From
this point as the chiller unloads and until it is shut-
down, the Main Steam Inlet Valve output will equal
the Governor Valve output. When the two valve signals
are tracking, the present LCLT Controller SP (Local/
Remote setpoint, whichever is selected) is ramped up
to a value equal to the return chiller liquid temp +5
°F and the chiller capacity controls begin unloading
the chiller. At the same time, a Soft Shutdown timer
(TDSP9-Soft Shutdown Rampdown Timer, adjustable
2-20 minutes on the Time Setpoints Screen) is enabled.
When the MSSP4-Turbine Start Mode is set for Manu-
al, when the Soft Shutdown is initiated, the unloading
proceeds immediately.
When the Speed Control Mode on Capacity Control
Setpoints Screen 1 is set for Variable, the unloading
begins with speed reduction to the calculated anti-
surge minimum speed. When the speed has decreased
to the calculated anti-surge minimum speed, the PRV
FORM 160.67-O1
ISSUE DATE: 4/1/2015
JOHNSON CONTROLS