Carrier PIC 5+ - Chiller Shutdown Sequence; Oil Lubrication Control

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5.3.1 - Prestart Check
Once start-up begins, the controller performs a series of
pre-start tests to verify that all pre-start alerts and safeties
are within the limits.
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STARTS IN 12 HOURS >= 8 100 Alert
OIL SUMP TEMP <= 140F AND OIL SUMP TEMP
<= EVAP_SAT + 50F
101 Alert
CONDENSER PRESSURE >= COND PRESS OVERRIDE
- 20 PSI
102 Alert
Number of recycle restart in the last 4 hours is greater than 5 103 Alert
COMP BEARING TEMP >= COMP BEARING ALERT- 10F 230 Alarm
COMP MOTOR WINDING TEMP >= MOTOR TEMP
OVERRIDE - 10F
231 Alarm
COMP DISCHARGE TEMP >= COMP DISCHARGE
ALERT- 10F
232 Alarm
EVAP_SAT < Evap trip point + EVAP OVERRIDE DELTA T
OR
EVAP REFRIG LIQUID TEMP < Evap trip point + EVAP
OVERRIDE DELTA T
NOTE: Evap trip point = 33F(water) or EVAP REFRIG
TRIPPOINT(brine)
233 Alarm
ACTUAL LINE VOLTAGE <= UNDERVOLTAGE
THRESHOLD
(N/A for Eaton/Rockwell UM VFDs) 234 Alarm
ACTUAL LINE VOLTAGE >= OVERVOLTAGE THRESHOLD
(N/A for Eaton/Rockwell UM VFDs) 235 Alarm
Guide vane 1 has not been calibrated successfully 236 Alarm
The compressor RUN STATUS parameter on the default
screen line now reads PRESTART. If one test is not
successful, the start-up is delayed or aborted. If all the tests
are successful, the chilled water pump relay energizes, and
the main screen line now reads STARTUP.
5.3.2 - Startup
One second later, the chilled and condenser water pump
relays are energized.
Five seconds later the control monitors the chilled water and
condenser water ow devices and waits until the WATER
FLOW VERIFY TIME (service-congured, default 5 minutes)
expires to conrm water ow.
After water ow is veried, the water temperature will be
compared to CONTROL POINT plus 1/2 CHILLED
WATER DEADBAND. If the temperature is less than or
equal to this value, the control turns off the condenser pump
relay and goes into a RECYCLE mode.
If the RECYCLE condition is not satisfied, the start-up
sequence continues and checks the guide vane position. For
single-stage compressor ( Comp(Single=0,Dual=1)=0 in
FACTORY conguration ), if the guide vanes are more than
GUIDE VANE CLOSURE AT STARTUP, the start-up waits
until the controller closes the vanes. For dual-stage compressor
(Comp(Single=0,Dual=1)=1 in FACTORY conguration ),
guide vane is to be opened to the initial position “GV1 Closure
at Startup” at “Option Conguration” menu.
If EC valve or Economizer damper valve is equipped and
enabled, control checks the status of these valves position to
be fully closed.
If the vanes and valves position are veried.
When chiller type is 19XR, the oil pump pressure difference
is less than 6 psi (41.4 kPa), the oil pump relay will be
energized.The control then waits until the oil pressure
difference (OIL PRESS VERIFY TIME, operator-
congured, default of 40 seconds) reaches a maximum of 18
psi (124 kPa). After oil pressure is veried, the control waits
40 seconds for oil prelube.
When chiller type is 19XR6/7, and oil pump kept OFF for
over 50 hours. The oil prelube time will be 6 minutes instead
of 40 seconds.
When chiller type is 19DV, The control will check the
refrigerant pump pressure difference, refrigerant pump will
be turned ON if it passed. Then controller waits until the
refrigerant pump pressure difference reaches 12 psi (82.7
kPa). After ref pressure is veried, if high side oat chamber
with liquid level, refrigerant pump will be kept ON for 20
seconds; if not, refrigerant pump will be kept ON until there
is liquid level, and then kept on 10 seconds after that.
The compressor start relay energizes to start the compressor.
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Chiller shutdown begins if any of the following occurs:
- Local OFF button is pressed
- A recycle condition is present (see Recycle Mode section)
- The time schedule has gone into unoccupied mode when
in Network or Local Schedule control mode
- The chiller protective limit has been reached and chiller
is in alarm
- The start/stop status (CHIL_S_S) is overridden to stop
from the network when in Network mode
If the chiller is normally shutdown from running, soft stop
shutdown will be performed. The soft stop feature closes the
guide vanes of the compressor automatically if a non-alarm
stop signal occurs before the compressor motor is deenergized.
Any time the compressor is directed to STOP (except in the
cases of a fault shutdown), the guide vanes are directed to
close and VFD will be command to minimum speed for
variable speed compressor, and the compressor shuts off
when any of the following is true:
- PERCENT LOAD CURRENT (%) drops below the
SOFT STOP AMPS THRESHOLD
- ACTUAL GUIDE VANE POSITION drops below 4%
- 4 minutes have elapsed after initinize the stop
When any one of the above condition is true, the shutdown
sequence stops the compressor by deactivating the
compressor start relay.
Then the guide vane shall be closed and stay at the fully
closed position.
When chiller type is 19XR2~E, the oil pump relay will be
Turned OFF after 60 seconds post lube.
When chiller type is 19XR6/7, the oil pump relay will be
Turned OFF after 120 seconds post lube.
When chiller type is 19DV, the refrigerant pump relay will
be Turne OFF after 120 seconds post lube.
And then the chilled water/brine pump and condenser water
pump will be shutdown.