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FORM 160.72-O1 (810)
seCTion 4 - general operaTing seQuenCe
uniT noT operaTing
1.
Control power is available to the control panel.
2.
Compressor oil heaters are enabled to maintain
proper temperature at oil sump.
3.
The capacity controls are disabled. The compres-
sor pre-rotation vanes and the interstage control
valve are closed. The hot gas bypass and subcooler
level control valves are open.
sYsTeM sTarTup
1.
All chiller safety logic must be satisfied prior to
starting, with the exception of the compressor and
gearbox low oil pressure, the chilled water and
condenser water low differential pressure, and the
Vibration Monitor Trip Contacts, if enabled. The
oil pressure safeties are bypassed initially, until
the auxiliary oil pumps can establish pressures.
The differential pressure safeties are bypassed
until the water pumps can establish flows. The
Vibration Monitor Trip Contacts are bypassed at
shutdown and until 2 seconds after the compres-
sor motor has started to prevent nuisance trips
caused by the temporary excessive vibrations dur-
ing start-up and shutdown.
The CLEAR MESSAGE button on the display
must be pushed to clear any previous safety trips
or power failures (if any).
A status indicator box in the upper left
corner will display the GREEN text SYS-
TEM READY TO START. This display
will change at various times during the
start-up, operation, and shutdown of the
chiller.
If the chiller has been recently started and shut
down, the motor must remain off for sufficient
time to cool down. See ANTI-RECYCLE OPER-
ATION for further details.
2.
The chiller start may be initiated at this time by
moving the COMPRESSOR SWITCH button to
the start position. The switch is spring-loaded to
return to the run position.
JOHNSON CONTROLS
Local vs. Remote control of the start is
established by the condition of the CON-
TROL SOURCE buttons on the OPERA-
TIONS Screen, To enable a remote start,
the source must be set to BAS, Analog, or
Digital Control.
When in LOCAL, the start sequence begins as
soon as the operator moves the COMPRESSOR
SWITCH button on the front of the chiller control
panel to the start position.
When in REMOTE with Remote Start Enabled,
the REMOTE START CONTACT must close to
initiate the chiller start sequence.
The chilled and condenser water flows
must be established by the customer's
pump control system or manually by the
operator at least 5 seconds before the
end of the pre-lube timer (an adjustable
timer set on the timer setpoint screen, as
described on page 63) in order to close the
chilled and condenser water low differen-
tial pressure cutout contacts and continue
with the start sequence.
3.
With the above INITIATE START signal, the
chiller controls start the compressor auxiliary oil
pump and the gear auxiliary oil pump, if appli-
cable, and their respective LED symbols on the
display will illuminate in RED.
If auxiliary run contacts are enabled and the
pumps fail to start within the programmed time
for feedback after the start signal is energized, an
alarm signal will be transmitted to the DISPLAY
for indication and recording.
The compressor pre-rotation vanes are opened
to their minimum position necessary to prevent
SURGING during the initial acceleration at start-
up. This value can be adjusted on the CAPACITY
CONTROLS TUNING Screen.
4.
Five seconds before the end of the pre-lube time,
the compressor and gearbox, if applicable, low oil
pressure signals and low pressure cutout switch-
es are checked. The chilled and condenser water
low differential pressure cutout switches are also
checked.
4
119
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