Start-Up/Recycle Operation; Temperature Control During Ice Build; Termination Of Ice Build; Return To Non-Ice Build Operations - Carrier 19XRV Start-Up, Operation And Maintenance Instructions Manual

NOTE: The Ice Build steps do not occur if the chiller is config-
ured and operating as a lag or standby chiller for lead/lag
operation and is actively being controlled by a lead chiller. The
lead chiller communicates the ICE BUILD SET POINT, the
desired CHILLER START/STOP state, and the ACTIVE
DEMAND LIMIT to the lag or standby chiller as required for
ice build, if configured to do so.
START-UP/RECYCLE OPERATION — If the chiller is not
running when ice build activates, the PIC III checks the fol-
lowing conditions, based on the ICE BUILD TERMINATION
value, to avoid starting the compressor unnecessarily:
• if ICE BUILD TERMINATION is set to the TEMP option
and the ENTERING CHILLED WATER temperature is
less than or equal to the ICE BUILD SETPOINT;
• if ICE BUILD TERMINATION is set to the CONTACTS
option and the ICE BUILD CONTACT is open;
• if the ICE BUILD TERMINATION is set to the BOTH
(temperature and contacts) option and the ENTERING
CHILLED WATER temperature is less than or equal
to the ICE BUILD SETPOINT and the ICE BUILD
CONTACT is open.
The ICE BUILD RECYCLE on the OPTIONS screen
determines whether or not the chiller will go into an ice build
RECYCLE mode.
• If the ICE BUILD RECYCLE is set to DSABLE (disable),
the PIC III reverts to normal (non-ice build) temperature
control when the ice build function is terminated by
satisfying one of the above conditions. Once ice build is
terminated in this manner, it will not be reinitiated until
the next ice build schedule period begins.
• If the ICE BUILD RECYCLE is set to ENABLE, the PIC
III goes into an ICE BUILD RECYCLE mode, and the
chilled water pump relay remains energized to keep the
chilled water flowing when the compressor shuts down.
If the temperature of the LEAVING CHILLED WATER
later increases above the ICE BUILD SETPOINT plus
half the RECYCLE RESTART DELTA T value, the
compressor restarts, controlling the chilled water/brine
temperature to the ICE BUILD SETPOINT.
TEMPERATURE CONTROL DURING ICE BUILD —
During ice build, the capacity control algorithm shall use the
CONTROL POINT minus 5 F (–2.8 C) for control of
the LEAVING CHILLED WATER temperature. The ECW
CONTROL OPTION and any temperature reset option shall be
ignored, if enabled, during ice build. Also, the following
control options will be ignored during ice build operation:
• ECW CONTROL OPTION and any temperature reset
options (configured on TEMP_CTL screen).
• 20 mA DEMAND LIMIT OPT (configured on
RAMP_DEM screen).
TERMINATION OF ICE BUILD — The ice build function
terminates under the following conditions:
1. Time Schedule — When the current time on the ice build
time schedule (OCCPC02S) is not set as an ice build time
period.
2. Entering Chilled Water Temperature — Ice build opera-
tion terminates, based on temperature, if the ICE BUILD
TERMINATION parameter is set to 0 (TEMP), the
ENTERING CHILLED WATER temperature is less
than the ICE BUILD SETPOINT, and the ICE BUILD
RECYCLE is set to DSABLE. If the ICE BUILD
RECYCLE OPTION is set to ENABLE, a recycle
shutdown occurs and recycle start-up depends on
the LEAVING CHILLED WATER temperature being
greater than the water/brine CONTROL POINT plus the
RESTART DELTA T temperature.
3. Remote Contacts/Ice Level Input — Ice build operation
terminates when the ICE BUILD TERMINATION param-
eter is set to 1 (CONTACTS) and the ICE BUILD
CONTACTS are open and the ICE BUILD RECYCLE is
set to DSABLE (0). In this case, the ICE BUILD
CONTACTS provide ice level termination control. The
contacts are used to stop the ice build function when a
time period on the ice build schedule (OCCPC02S) is set
for ice build operation. The remote contacts can still be
opened and closed to start and stop the chiller when a
specific time period on the ice build schedule is not set for
ice build.
4. Entering Chilled Water Temperature and ICE BUILD
Contacts — Ice Build operation terminates when the ICE
BUILD TERMINATION parameter is set to 2 (BOTH)
and the conditions described above in items 2 and 3 for
ENTERING CHILLED WATER temperature and ICE
BUILD CONTACTS have occurred.
NOTE: It is not possible to override the CHILLER START/
STOP, CONTROL POINT, and ACTIVE DEMAND LIMIT
variables from CCN devices (with a priority 4 or greater)
during the ice build period. However, a CCN device can
override these settings during 2-chiller lead/lag operation.
RETURN TO NON-ICE BUILD OPERATIONS — The ice
build function forces the chiller to start, even if all other sched-
ules indicate that the chiller should stop. When the ice build
function terminates, the chiller returns to normal temperature
control and start/stop schedule operation. The CHILLER START/
STOP and CONTROL POINT return to normal operation. If the
CHILLER START/STOP or CONTROL POINT has been forced
(with a device of less than 4 priority) before the ice build func-
tion started, when the ice build function ends, the previous forces
(of less than 4 priority) are not automatically restored.
Attach to Network Device Control —
menu includes the ATTACH TO NETWORK DEVICE
screen. From this screen, the operator can:
• enter the time schedule number (if changed) for
OCCPC03S, as defined in the NET_OPT screen
• attach the ICVC to any CCN device, if the chiller has
been connected to a CCN network. This may include
other PIC-controlled chillers.
• upgrade software
Figure 25 shows the ATTACH TO NETWORK DEVICE
screen. The LOCAL parameter is always the ICVC module
address of the chiller on which it is mounted. Whenever the
controller identification of the ICVC changes, the change is
reflected automatically in the BUS and ADDRESS columns
for the local device. See Fig. 18. Default address for local
device is BUS 0 ADDRESS 1.
When the ATTACH TO NETWORK DEVICE screen is
accessed, information can not be read from the ICVC on any
device until one of the devices listed on that screen is attached.
The ICVC erases information about the module to which it was
attached to make room for information on another device.
Therefore, a CCN module must be attached when this screen is
entered.
To attach any CCN device, highlight it using the
softkey and press the
"UPLOADING TABLES, PLEASE WAIT" displays. The
ICVC then uploads the highlighted device or module. If
the module address cannot be found, the message "COMMU-
NICATION FAILURE" appears. The ICVC then reverts back
to the ATTACH TO DEVICE screen. Try another device or
check the address of the device that would not attach. The
upload process time for each CCN module is different. In
general, the uploading process takes 1 to 2 minutes. Before
leaving the ATTACH TO NETWORK DEVICE screen, select
the LOCAL device. Otherwise, the ICVC will be unable to
display information on the local chiller.
50
The Service
SELECT
softkey. The message
ATTACH