JOHNSON CONTROLS
35
SECTION 2 - PRE-STARTUP AND SYSTEM OPERATING PROCEDURES
FORM 160.67-O2
ISSUE DATE: 10/9/2020
2
are increased to initiate the Capacity Ratchet
Mode change to PRV before the HGV has actually
closed fully and the mode change to Speed before
the vanes have actually opened fully. This will al-
low the vanes and speed to begin increasing the
capacity sooner and provide a faster pull-down to
the system design conditions.
21. Under full load conditions, when the PRV control
signal is at 100%, the speed setpoint is ramped up
to the 4500 RPM at 10 RPM/second. If the cool-
ing load is low, the chiller will continue to run at
the calculated anti-surge minimum speed. As the
system head increases, the speed will increase to
the higher calculated anti-surge minimum speed.
As the vanes are ramping open, if the leaving
chilled liquid temperature decreases to less than
2ºF above the leaving chilled liquid temperature
controller setpoint, the controls will automatically
override the ramp signals to prevent over shooting
the setpoint. The capacity control/anti-surge logic
will always adjust the turbine speed and compres-
sor pre-rotation vanes as required, providing sta-
ble operation and maintaining the leaving chilled
liquid temperature at set point.
22. Verify general operation, oil pressures, tempera-
tures, vibration and noise levels, and hotwell con-
densate level.
23. After the chiller has been running at or above
the minimum rated speed for 10 minutes, the
subcooler refrigerant liquid level controller
setpoint is ramped up to the desired setpoint at
the 0.1 %/second. This causes the subcooler level
control valve to slowly close until the refrigerant
level in the subcooler is at the setpoint.
24. After the chiller has achieved the SYSTEM RUN
mode, if the turbine exhaust pressure increases
above 3.5 PSIA for a continuous period of 10
seconds, the warning message "TURBINE EX-
HAUST HIGH PRESSURE" will be displayed. If
the pressure remains above the set point for 10
minutes, the turbine will be tripped.
SYSTEM OPERATING PROCEDURE
General
Refer to the OPERATING INSPECTIONS in this
manual for complete details on the routine operation
of the equipment.
For turbines with pressure feed lubrica-
tion, the oil pressure should be observed
frequently until the turbine has been
operated for several days as failure of oil
pressure can result in extensive damage.
The oil reservoirs should be maintained
at the proper level using oil of the recom-
mended grade.
Hourly
Record operating readings. Walk through chiller area
and perform a visual inspection of turbine, compressor,
steam system and control panel. Listen for any unusual
noises.
Check turbine ring pressure verses steam inlet pressure.
Open or close nozzle valves to maintain ring pressure
at approximately 90 percent of steam inlet pressure. If
an increase in load is expected, nozzle valves may be
left open to ensure reserve turbine horsepower. How-
ever, optimum turbine performance is achieved by
having the least number of nozzle valves opened while
maintaining the horsepower required for the load.
Do not partially open nozzle hand valves.
Valves should be fully open or fully closed.
Leaving the valves partially open could
cause seat and valve damage.
Automatic Start: The nozzle valves are opened/closed
automatically based on the turbine first stage pressure
that varies with each application. As the load on the
turbine increases, the governor valve opens and the
first stage pressure increases. When the first stage pres-
sure has been above the Turbine Nozzle Solenoid #1
Activate pressure setpoint continuously for 300 sec-
onds, Nozzle Solenoid #1 is energized to open addi-
tional inlet nozzles and increase the horsepower output
of the turbine. If the load continues to increase and the
first stage pressure has been above the Turbine Nozzle
Solenoid #2 Activate pressure setpoint continuously
for 100 seconds, Nozzle Solenoid #2 is energized to
open additional inlet nozzles. If the load decreases,
the governor valve closes and the first stage pressure
decreases. Each nozzle valve will be closed when the
pressure decreases 5 PSIG below the respective acti-
vate setpoint.
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