Emerson Process Management ControlWave XFC - Manual (Page 112)

F-10 / Appendix F CI-ControlWave XFC
Stop: day/hour
The actual stop day of the month (1-31) and stop hour (1-23) when the next nomination
period is to end is displayed or entered. The stop day is ignored if the daily nomination
feature is enabled.
Target Value (x 1000)
The Target value is used to set the value of Volume/Energy to be delivered during the
next nomination period.
LAST NOMINATION PERIOD - This section allows the operator to view information
associated with the last nomination period which was completed. Information displayed
remains valid until the next time a nomination period ends (when the information is up-
graded to reflect the new "last" nomination period). Start and end times stored here
indicate the actual time that the nomination period ended, which is not necessarily the
programmed time (because of the time required to close/open valves or complete other
actions). The days are valid even if the daily nomination mode is active.
3. Program all the configuration items for the NEXT Nomination Period such as start
and stop times and target value.
4. Set the desired parameters for NOMINATION CONTROL such as Quantity units,
Control mode, Stop mode, Daily only mode and Alarm at a level of and then set the Main
function signal to the Enable State.
5. If a radio or modem is to be used in conjunction with a "logical nomination alarm,"
access the Radio & Modem Control Configuration Web Page (see Figure F-12) via the
Radio Control button. See Section F.5.6 to configure the radio or modem for logical
nomination alarms.
F.5.4.1.2 Beginning a Nomination Period
When no nomination period is in progress, the ControlWave XFC compares the NEXT
start date and time to the current time. If the date and time match (or time only for the
daily nomination mode), a new period is begun. The current time is copied into the
CURRENT START signals, and the next target is copied into the current target. The ac-
cumulators for the current period are zeroed and the current stop time is set to the next
start time. If the PID mode is selected, a new flow setpoint is calculated and stored in the
setpoint signal. The PID setpoint is recalculated every 15 minutes and whenever any
parameter is changed.
F.5.4.1.3 Ending a Nomination Period
If shut-in on stop mode is in use, the current period will end when the target accumulation
is reached. At this time, the ControlWave XFC attempts to close the control valve. If PID
control is being used, the setpoint is set to 0.0, the current cycle will ramp down
accordingly. When the flow rate reaches 0.0, the current cycle accumulations and the actual
end time are copied into the LAST signals. If the valve fails to close, the volume will
continue to accumulate until the programmed end time. If the shut-in on stop mode is not
in use, the nomination period continues until the programmed end time.
F.5.4.1.4 Changing the Nomination Target
To change the target of the next period, the user should change the NEXT TARGET signal.