Emerson Process Management ControlWave XFC - Manual (Page 109)

CI-ControlWave XFC Appendix F / F- 7
F.5.4 Nomination
Users configure the nominations control from the Nomination WebPage. Nominations
functionally provide the user with the ability to set the ControlWave XFC to allocate
precise amounts of gas flow during specific time periods. These periods are called
“nomination periods.” A nomination may be set for any duration of time (not to exceed one
month). The volume to be delivered (nominated) during a nomination period is the target.
Targets may be specified in terms of volume or energy. Users set a nomination period by
keying in the desired day of the month and hour to begin the period and the desired day of
the month and hour to end the period. The daily nomination feature is used if the user
desires the same start/stop times every day. A unit programmed with a daily nomination,
will ignore the programmed start and end day numbers and will perform the nomination in
question at the same time once per day.
The delivery of the nominated quantity (volume or energy during the nomination period)
may be performed via one of the two unique schemes listed below.
Valve Control
The Valve Control method overrides PID flow control and allows the valve to be
independently controlled, thus permiting full flow of gas through the meter in order to
arrive at the target (volume or energy) as quickly as possible without regard to the
programmed end time.
Flow Control
The Flow Control method internally enables the PID flow control algorithm in order to hit
the target volume/energy at exactly the programmed end time.
The user programs the ControlWave XFC (via the ‘Stop Mode’ button) to either close the
valve upon reaching the target or leave it in its last position.
Figure F-8 - Nomination Web Page
F.5.4.1 Nomination Operation
See sections F.5.4.1.1 through F.5.4.1.5.