Pressure Setpoints Screen; Figure 40 - Pressure Setpoints Screen - York YST Operation Manual

FORM 160.67-O1
ISSUE DATE: 4/1/2015
noTe: OptiView Control Center Screens shown may NOT represent the exact screens according to the software version utilized.
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figure 40 - preSSure SeTpoinTS SCreen

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This screen allows programming of various pressure
thresholds pertinent to the operation of the chiller and
the optional equipment supplied. It is also a gateway
to screens for programming time delays, speeds, and
ramp rates pertinent to the operation of the chiller. In
order to better understand how these setpoints are used
in the logic, references are made to the applicable page
number of YORK YST Logic Diagram 160.67-M3
where the setpoint has visibility. 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.
prograMMable
pSp5 – vacuum pump Shutdown
Screen: Vacuum
Range: 0-10.0 PSIA
This determines when the vacuum pump is stopped
during slow roll. During the slow roll, an extremely
low exhaust pressure may cause speed instability;
therefore this is usually set at 9 PSIA. When the
chiller is supplied with a steam condenser that uses a
single vacuum pump and steam ejectors to maintain
the required turbine exhaust pressure and MSSP11-
Vacuum Pump Mode on Configuration Screen 1 is set
for Ejector, this determines when the vacuum pump is
JOHNSON CONTROLS

preSSure SeTpoinTS SCreen

Default: 9.0 PSIA
SECTION 2 - OPTIVIEW CONTROL CENTER INTRODUCTION
stopped during slow roll and normal operation. After
the vacuum pump has pulled the exhaust pressure
down below the PSP12-Open Ejector Steam Inlet
pressure and the ejectors are operating, the turbine
exhaust pressure will decrease rapidly. The vacuum
pump is stopped when the turbine exhaust pressure has
decreased to this setpoint.
pSp6 – ready To run
Screen: Steam System
Range: 0-15.0 PSIA
This determines when the turbine can be ramped up to
rated speed. After the slow roll timer has decremented
to 0, and the turbine exhaust pressure has been reduced
to this value, the message READY TO RUN is dis-
played until the "Run At Rated" key that appears on the
Steam System Screen is pressed to close the Chilled
Liquid Pump Start contacts and initiate the ramp up to
rated speed. When MSSP4-Turbine Start Mode is set
for Auto on Configuration Screen 1, the Chilled Liq-
uid Pump Start contacts are closed automatically when
this message appears. If the vacuum pump has been
stopped, it will be restarted if the exhaust pressure in-
creases to this value during slow roll and the ramp up
to rated speed.
LD09280
Default: 12.0 PSIA
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