JOHNSON CONTROLS
33
SECTION 2 - PRE-STARTUP AND SYSTEM OPERATING PROCEDURES
FORM 160.67-O2
ISSUE DATE: 10/9/2020
2
12. Perform the following while the turbine is slow
rolling:
a. Check turbine and compressor for proper op-
eration of lubrication system.
When starting a turbine with cold oil, the oil
pressure will be somewhat higher than when
the oil reaches operating temperature. This
is a natural condition due to the change in oil
viscosity with temperature. ANY ADJUST-
MENT TO OIL PRESSURE SHOULD BE
MADE WITH THE OIL AT OPERATING
TEMPERATURE.
b. Check for vibration or any unusual noise or
condition.
c. Check hotwell pump and pneumatic con-
densate level controls for proper operation.
If the pump or level controls fail, the con-
densate level in the hotwell will increase. If
the hotwell high level switch contacts wired
to terminals 1 & 80 of the I/O board remain
open for 10 seconds, the turbine will be
tripped and the message HOTWELL CON-
DENSATE HIGH LEVEL will be displayed.
d. Check atmospheric relief valve sealing wa-
ter.
e. Check that the automatic turbine condensate
removal system is operating properly. Dur-
ing slow roll, the system should be cycling
as required to drain the condensate from the
exhaust end of the turbine.
13. During the slow roll period, the evaporator low-
pressure cutout is raised to 30 PSIG. If the slow
rolling produces enough ow through the com-
pressor to reduce the evaporator pressure below
this elevated pressure, the turbine will be tripped
immediately. If the turbine speed increases above
1500 RPM, the chilled liquid pump contacts (ter-
minals 44-45 on the I/O board) are closed to start
the chilled liquid pump.
If the chilled liquid pump contacts are not used,
the plant control system or operator must ensure
that the chilled liquid flow is established within
10 seconds after these contacts are closed. Oth-
erwise, the low flow switch will trip the chiller.
14. After the chiller has been slow rolled for the cal-
culated time, the message "TURBINE IDLING
– INSUFFICIENT VACUUM" is displayed if the
turbine exhaust pressure is not less than the PSP6-
Ready To Run Turbine Exhaust Pressure setpoint
(12 PSIA) and the vacuum pump is restarted. This
energizes the sealing water solenoid valve. If
ow is not established within 10 seconds after the
pump start is initiated, an alarm is sounded. If the
chiller is equipped with a standby vacuum pump,
it will be started to continue with the startup, oth-
erwise the startup will be aborted.
If the chiller is equipped with an optional standby
pump, in the automatic mode, the vacuum pumps
will be switched-over to share operational time. If
the lead pump fails to start or fails while the chill-
er is operating, toggle to standby pump will be
done automatically. If both pumps fail, the chiller
will be not be allowed to start and will shutdown
if operating.
15. When the turbine exhaust pressure has decreased
to the PSP6- Ready To Run Turbine Exhaust Pres-
sure setpoint (12 PSIA), the turbine should be
able to be safely ramped up to rated speed since
there is essentially no load with the compressor
pre-rotation vanes closed and the hot gas valve
fully open. The message "READY TO RUN" is
displayed. Slowly open the main steam inlet block
valve and then press the RUN AT RATED key that
appears on the STEAM SYSTEM screen.
Chillers manufactured after December 2006 DO
NOT require the manipulation of the main steam
inlet block valve. The output signal to the valve
controller automatically modulates the ball valve
position to achieve and maintain the fixed rated
speed.
If the RUN AT RATED button is not
pressed within 20 minutes after the slow
roll time has elapsed, the chiller will be
tripped and the message "EXCESSIVE
SLOW ROLLING TRIP" will be dis-
played.
Automatic Start: The RUN AT RATED key does
not appear and the start sequence proceeds to
paragraph
16. The chilled liquid pump contacts (terminals 44-45
on the relay output board) are closed to start the
chilled liquid pump.
If the chilled liquid pump contacts are not used,
the plant control system or the operator must
ensure that the chilled liquid flow is established
within 10 seconds after these contacts are closed.
Otherwise, the flow switch will trip the chiller.
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