JOHNSON CONTROLS
37
SECTION 2 - PRE-STARTUP AND SYSTEM OPERATING PROCEDURES
FORM 160.67-O2
ISSUE DATE: 10/9/2020
2
Automatic Start: The main steam inlet block valve
air dump solenoid is de-energized to close the
valve immediately and its control signal is set to
0%. The steam inlet slow roll bypass valve control
signal is also set to 0% to close the valve.
Chillers manufactured after December
2006 are not supplied with separate au-
tomatic slow roll bypass and main steam
inlet valves.
The vacuum pump is stopped and the vacuum breaker
solenoid valve is opened to break the vacuum in the
exhaust line and slow the turbine down faster.
The speed control set point is set to 0 RPM which
causes the control output signal to the governor valve
to decrease to 0% and close the governor valve.
In the case of a mechanical trip, when the trip valve is
actuated by hand or by an over speed condition not de-
tected by the control panel logic, the trip valve closed
limit switch is actuated for feedback to the control
panel and the message "TURBINE MECHANICAL
TRIP" is displayed.
2. When the speed decreases below 3000 RPM,
the oil return and liquid line solenoid valves
are closed and the turbine auxiliary oil pump (if
equipped) is started. If the chiller is supplied with
a solenoid valve in the turbine steam ring drain
line, it is opened at this time.
3. During the coast down of the drive train and the
compressor oil pump and turbine auxiliary oil
pump (if equipped) will continue to run to main-
tain lubrication of the bearings and the message
"SYSTEM COASTDOWN" is displayed.
4. When rotation has ceased for 35 seconds, the
message "COMPRESSOR SHTDN; TURBINE
COOLDOWN" is displayed if the turbine has
Pump Lubrication. If the turbine has Ring Lubrica-
tion the message "SYSTEM READY TO START"
is displayed.
5. When the compressor oil pump has been stopped
for 35 seconds, the chilled liquid pump contacts
(terminals 44-45 on the I/O board) are opened to
stop the chilled liquid pump unless the cycling
shutdown message "LEAVING CHILLED LIQ-
UID – LOW TEMPERATURE" is displayed, in
which case the contacts will remain closed. If the
Chilled Liquid Pump Operation is set for Enhanced
on the Setup Screen, the contacts will also remain
closed if the cycling shutdown message "SYSTEM
CYCLING – CONTACTS OPEN" is displayed.
If the chilled liquid pump contacts are not
used, the plant control system or operator
should shut o the chilled liquid ow at
this time.
6. The turbine auxiliary oil pump (if equipped) will
continue to run for 30 minutes to remove excess
heat from the turbine bearings.
The drive train will normally coast to a
complete stop within 6 minutes after a trip.
If for any reason the turbine is still rotat-
ing 6 minutes after the trip, the Oil Pumps
will continue to operate. If the Turbine
begins rotating again after having come
to a complete stop, the message "STEAM
SUPPLY VALVE MALFUNCTION" is
displayed and the oil pumps will be re-
started. Verify that the governor valve,
pneumatic trip valve, and main steam
inlet block valves are all fully closed and
no steam is entering the turbine.
7. Six minutes after the turbine was tripped, if no
rotation is detected, the condenser liquid and
hotwell pumps are stopped and the oil cooler liq-
uid valves are closed. If the chiller is not supplied
with a solenoid in the turbine steam ring drain line
and the chiller will not be restarted in a short time
(the turbine will be allowed to cool down), open
the manual valve in the steam ring drain line.
If the condenser liquid pump contacts
are not used, the plant control system or
operator should shut o the condenser
liquid ow at this time.
8. Thirty minutes after the rotation has stopped, the
turbine auxiliary lube oil pump (if equipped) will
be stopped and the message "SYSTEM READY
TO START" is displayed.
If the trip was caused by a power failure and the
power is restored within 6 minutes of the last
chiller run cycle, the oil pumps are started as soon
as the power is restored. The compressor oil pump
will then run for 35 seconds and stop. The turbine
auxiliary oil pump (if equipped) will run for 30
minutes and stop.
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