62
action returns the chiller to the start and stop times established
by the schedule.
The chiller may also be started by overriding the time sched-
ule. From the default screen, press the and
softkeys. Scroll down and select the current
schedule. Select OVERRIDE, and set the desired override time.
Another condition for start-up must be met for chillers that
have the REMOTE CONTACTS OPTION on the EQUIP-
MENT SERVICE screen set to ENABLE. For these chillers,
the REMOTE START CONTACT parameter on the MAIN-
STAT screen must be CLOSED. From the ICVC default
screen, press the and softkeys. Scroll to
highlight MAINSTAT and press the softkey. Scroll
down the MAINSTAT screen to highlight REMOTE START
CONTACT and press the softkey. Then, press the
softkey. To end the override, select REMOTE
CONTACTS INPUT and press the softkey.
Once local start-up begins, the PIC III performs a series of
pre-start tests to verify that all pre-start alerts and safeties are
within the limits shown in Table 9. The RUN STATUS parame-
ter on the MAINSTAT screen line now reads PRESTART. If a
test is not successful, the start-up is delayed or aborted. If the
tests are successful, the CHILLED WATER PUMP relay ener-
gizes, and the RUN STATUS line now reads STARTUP. See
Table 9.
Five seconds later, the CONDENSER WATER PUMP relay
energizes. Thirty seconds later, the PIC III monitors the chilled
water and condenser water flow devices and waits until the
WATER FLOW VERIFY TIME (operator-configured, default
5 minutes) expires to confirm flow. After flow is verified, the
chilled water temperature is compared to CONTROL POINT
plus
1
/
2
CHILLED WATER DEADBAND. If the temperature is
less than or equal to this value, the PIC III turns off
the CONDENSER WATER PUMP relay and goes into a
RECYCLE mode.
NOTE: The 19XRV units are not available with factory-
installed chilled water or condenser water flow devices (avail-
able as an accessory for use with the CCM control board).
If the water/brine temperature is high enough, the start-up
sequence continues and checks the guide vane position. If the
guide vanes are more than 4% open or if Auto-Restart is not
enabled, the start-up is delayed until the PIC III closes the
vanes. If the vanes are closed or if Auto-Restart is enabled, and
the oil pump pressure is less than 4 psi (28 kPa), the oil pump
relay energizes. The PIC III then waits until the oil pressure
(OIL PRESS VERIFY TIME, operator-configured, default of
40 seconds) reaches a maximum of 18 psi (124 kPa). After oil
pressure is verified, the PIC III waits 40 seconds, and the VFD
energizes to start the compressor.
Compressor ontime and service ontime timers start, and the
compressor STARTS IN 12 HOURS counter and the number of
starts over a 12-hour period counter advance by one.
Failure to verify any of the requirements up to this point will
result in the PIC III aborting the start and displaying the appli-
cable pre-start mode of failure on the ICVC default screen. A
pre-start failure does not advance the STARTS IN 12 HOURS
counter. Any failure after the VFD has energized results in a
safety shutdown, advances the starts in 12 hours counter by
one, and displays the applicable shutdown status on the ICVC
display. The minimum time to complete the entire prestart
sequence is approximately 185 seconds if Auto-Restart is not
enabled.
Shutdown Sequence — Chiller shutdown begins if
any of the following occurs:
• the STOP button is pressed for at least one second (the
alarm light blinks once to confirm the stop command)
• a recycle condition is present (see Chilled Water Recycle
Mode section)
• the time schedule has gone into unoccupied mode
• the chiller protective limit has been reached and chiller is in
alarm
• the start/stop status is overridden to stop from the CCN net-
work or the ICVC
When a stop signal occurs, the shutdown sequence first
stops the compressor by deactivating the VFD output to the
motor. A status message of “SHUTDOWN IN PROGRESS,
COMPRESSOR DEENERGIZED” is displayed, and the
compressor ontime and service ontime stop. The guide vanes
are then brought to the closed position. The oil pump relay and
the chilled water/brine pump relay shut down 60 seconds after
the compressor stops. The condenser water pump shuts down
at the same time if the ENTERING CONDENSER WATER
temperature is greater than or equal to 115 F (46.1 C) and
the CONDENSER REFRIG TEMP is greater than the
CONDENSER FREEZE POINT plus 5 F (–15.0 C). The
stop-to-start timer now begins to count down. If the
start-to-start timer value is still greater than the value of the
start-to-stop timer, then this time displays on the ICVC.
A—START INITIATED: Pre-start checks are made; evaporator pump
started. When Auto-Restart After Power Failure is enabled, a faster
timing sequence is used.
B—Condenser water pump started (5 seconds after A).
C—Water flows verified (30 seconds to 5 minutes maximum after B).
Chilled water temperatures checked against control point. Guide
vanes checked for closure. Oil pump started; tower fan control
enabled.
D—Oil pressure verified (15 seconds minimum, 300 seconds maximum
after C).
E—Compressor motor starts; compressor ontime and service ontime
start, 15-minute inhibit timer starts (10 seconds after D), total com-
pressor starts advances by one, and the number of starts over a
12-hour period advances by one.
F—SHUTDOWN INITIATED — Compressor motor stops; compressor
ontime and service ontime stop, and 1-minute inhibit timer starts.
G—Oil pump and evaporator pumps deenergized (60 seconds after F).
Condenser pump and tower fan control may continue to operate if
condenser pressure is high. Evaporator pump may continue if in
RECYCLE mode.
O/A — Restart permitted (both inhibit timers expired: minimum of 15 min-
utes after E; minimum of 1 minute after F).
Fig. 32 — Control Timing Sequence When
Auto-Restart Is Not Enabled
a19-765
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