Auto. Restart After Power Failure; Water/Brine Reset; Reset Type 2: Remote Temperature Reset; Reset Type - Carrier 19XRV Start-Up, Operation And Maintenance Instructions Manual

The TOWER FAN RELAY HIGH is turned off when the
condenser pump is off, flow is stopped, or the EVAPORATOR
REFRIG TEMP is less than the EVAP REF OVERRIDE TEMP
and ENTERING CONDENSER WATER is less than 70 F
(21.1 C), or the difference between EVAPORATOR PRES-
SURE and CONDENSER PRESSURE is less than 28 Psid
(193 kPa), and ENTERING CONDENSER WATER tempera-
ture is less than TOWER FAN HIGH SETPOINT minus 3 F
(–16.1 C).
The TOWER FAN RELAY LOW and TOWER FAN RELAY
HIGH parameters are accessed from the STARTUP screen.
IMPORTANT: A field-supplied water temperature control
system for condenser water should be installed. The system
should maintain the leaving condenser water temperature
at a temperature that is at least 20° F (11° C) above the
leaving chilled water temperature.
The tower fan relay control is not a substitute for a con-
denser water temperature control. When used with a water
temperature control system, the tower fan relay control can
be used to help prevent low condenser water temperatures.
Auto. Restart After Power Failure —
may be enabled or disabled and may be viewed or modified
on the OPTIONS screen, which is accessed from the
EQUIPMENT CONFIGURATION table. If the AUTO
RESTART OPTION is enabled, the chiller will start up automati-
cally after a power failure has occurred, generating one of the
following faults: single cycle dropout (if enabled), line current
imbalance, high line voltage, low line voltage, low DC bus
voltage, high DC bus voltage, VFD power on reset, and ICVC
power on reset (alerts 143-148, 165, and 166). With this feature
enabled, these faults are treated as alerts instead of alarms, so
start-up proceeds as soon as the condition is rectified. The 15
and 1-minute start inhibit timers are ignored during this type of
start-up, and the STARTS IN 12 HOURS counter is not
incremented.
When power is restored after the power failure and if the
compressor had been running, the oil pump will energize
for one minute before energizing the cooler pump. AUTO
RESTART will then continue like a normal start-up.
If power to the ICVC module has been off for more than
3 hours or the timeclock has been set for the first time, start the
compressor with the slowest TEMP PULLDOWN DEG/MIN
rate possible in order to minimize oil foaming.
The oil pump is energized occasionally during the time the
oil is being brought up to proper temperature in order to elimi-
nate refrigerant that has migrated to the oil sump during the
power failure. The pump turns on for 30 seconds at the end of
every 30-minute period until the chiller is started.
Water/Brine Reset —
based on achieving and maintaining a CONTROL POINT
temperature, which is the sum of the LCW SET POINT or ECW
SETPOINT (from the SETPOINT screen) and a Water/Brine
Reset value, if any. CONTROL POINT is limited to a minimum
of 35 F (+1.7 C) for water, or 10 F (–12.2 C) for brine. Three
types of chilled water or brine reset are available and can be
viewed or modified on the TEMP_CTL screen, which is
accessed from the EQUIPMENT SERVICE table.
The ICVC default screen indicates when the chilled water
reset is active. TEMPERATURE RESET on the MAINSTAT
screen indicates the amount of reset. The CONTROL POINT
will be determined by adding the TEMPERATURE RESET to
the SETPOINT.
To activate a reset type, access the TEMP_CTL screen and
input all configuration information for that reset type. Then,
This option
Chilled water capacity control is
input the reset type number (1, 2, or 3) in the SELECT/
ENABLE RESET TYPE input line.
RESET TYPE 1: 4 to 20 mA (1 to 5 vdc) TEMPERATURE
RESET – Reset Type 1 is an "automatic" reset utilizing a 4 to
20 mA or 1 to 5 vdc analog input signal provided from any
external sensor, controller, or other device which is appropri-
ately configured. Reset Type 1 permits up to ±30° F (±16.7° C)
of reset to the chilled water set point. Inputs are wired to termi-
nals J5-3 (–) and J5-4 (+) on the CCM (for 4-20 mA input). In
order to utilize a 1 to 5 vdc input, a 250 ohm resistor must be
wired in series with the + input lead (J5-4). For either input
type, SW2 DIP switches should be set in the ON (up) position.
Inputs equivalent to less than 4 mA result in no reset, and
inputs exceeding 20 mA are treated as 20 mA.
RESET TYPE 2: REMOTE TEMPERATURE RESET —
Reset Type 2 is an automatic chilled water temperature reset
based on a remote temperature sensor input signal. Reset type
2 permits ± 30° F (± 16° C) of automatic reset to the set point
based on a temperature sensor wired to the CCM module (see
wiring diagrams or certified drawings). The temperature sensor
must be wired to terminal J4-13 and J4-14. To configure Reset
Type 2, enter the temperature of the remote sensor at the point
where no temperature reset will occur (REMOTE TEMP –>
NO RESET). Next, enter the temperature at which the full
amount of reset will occur (REMOTE TEMP –> FULL
RESET). Then, enter the maximum amount of reset required to
operate the chiller (DEGREES RESET). Reset Type 2 can now
be activated.
RESET TYPE 3 — Reset Type 3 is an automatic chilled water
temperature reset based on cooler temperature difference.
Reset Type 3 adds ± 30° F (± 16° C) based on the temperature
difference between the ENTERING CHILLED WATER and
LEAVING CHILLED WATER temperature.
To configure Reset Type 3, enter the chilled water tempera-
ture difference (the difference between entering and leaving
chilled water) at which no temperature reset occurs (CHW
DELTA T –> NO RESET). This chilled water temperature dif-
ference is usually the full design load temperature difference.
Next, enter the difference in chilled water temperature at which
the full amount of reset occurs (CHW DELTA T –> FULL RE-
SET). Finally, enter the amount of reset (DEGREES RESET).
Reset Type 3 can now be activated.
Surge Prevention Algorithm —
configurable feature that can determine if lift conditions are too
high for the compressor and then take corrective action. Lift is
defined as the difference between the pressure at the impeller
eye and at the impeller discharge. The maximum lift a particu-
lar impeller wheel can perform varies with the gas flow
through the impeller and the diameter of the impeller.
The lift capability (surge line) of a variable speed compres-
sor shifts upward as speed increases. Consequently, the line
which serves as the surge prevention threshold is made to shift
upward in a similar fashion as speed is increased. If the operat-
ing point goes above the surge prevention line as adjusted for
the current operating speed, then surge prevention actions are
taken. Note that the line constructed from SURGE/HGBP
DELTA T1, SURGE/HGBP DELTA P1, SURGE/HGBP
DELTA T2, and SURGE/HGBP DELTA P2 values is applied
to the full speed condition only. These surge characteristics are
factory set based on the original selection, with the values
printed on a label affixed to the bottom interior face of the con-
trol panel. Since operating conditions may affect the surge pre-
vention algorithm, some field adjustments may be necessary.
A chiller equipped with a VFD can adjust inlet guide posi-
tion or compressor speed to avoid surge (if not already at
COMPRESSOR 100% SPEED). Thus, the primary response
to entering the surge prevention region or incurring an actual
surge event (see the Surge Protection section) is to increase
compressor speed. This moves the compressor's surge line and
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