Emerson Site Supervisor, User Manual

Page: 70 / 141

Time Schedule Application Software Overview
•
5
-
15
Time to 23:59.
•
END DATE
- the date the maintenance override
should end in this field. If the maintenance override
is only going to last one day, enter the same date in
this field as is in the Start Date.
•
END TIME
- the end time at which the Time
Schedule will stop following the maintenance
override and start using its standard events. If you
want the maintenance override to be followed for
the entire day, leave this field set to 23:59 and the
Start Time to 0:00.
Note that the End Time is not the time you wish for
the Time Schedule to make a state transition, it is
the time when you want to end the schedule
override.
•
ON EVENT TIME
- The time of day you wish the
schedule output to be ON when the Time Schedule
application is following this maintenance override.
•
OFF EVENT TIME
- The time of day you wish
the schedule output to be OFF when the Time
Schedule application is following this maintenance
override.
Once the maintenance schedule is complete (moved
past the END DATE), the schedule application returns to
following its standard schedule. Maintenance Schedule is
active for the entire day and for all days between (and
including) the START DATE and END DATE.
5.7.5 Output Calculation
The Time Schedule control algorithm calculates the
current On/Off status, the time until change of state
(TUCOS) and time since change of state (TSCOS) for all
the schedules. This information is available for the other
applications that are making use of a particular schedule.
The schedules output status reflects the results of any
bypass or override, but there is also an output that reflects
the actual calculated value based on the time of day.
The Time Schedule control algorithm runs every
minute to determine the state of the schedule, but a new
bypass request or a new demand shed request is processed
immediately. A termination of a bypass or a demand shed
request is also processed immediately. The Time
Scheduling control algorithm is composed of a core
scheduling algorithm, bypass, override, and demand
control handling.
There may be outputs that the Time Schedule does
control directly and in these cases the user is able to enable
demand shedding of the output. If the Demand Control
Input indicates shed and if the schedule output is On, it is
turned Off. The load is turned back On at the next minute
advance when the Demand Control Input indicates restore.
5.7.6 Scheduling Logic
The core scheduling algorithm determines the state of
the active schedule. It does not take bypass, override, and
demand shed inputs into account. The core scheduling
algorithm operates under two different modes: either
Master or Slave as determined by the “Schedule Type”
input. The difference among these two operation modes is
the different usage of some inputs/outputs and their
corresponding values.
Schedule Priority
The schedule used is based on the following priority
scheme and within the following categories.
•
Maintenance Schedule
- If any of the maintenance
schedules are active, (in the Master Schedule) that
maintenance schedule is used as the current
schedule. Time until next change of state and time
since previous change of state will be given in
minutes.
•
Holiday/Special Schedule
- The DAY SCHED
input provides which day of the week or holiday
schedule to follow. When DAY SCHED input
indicates that a holiday is active, all schedules
follow the selected holiday schedule. If a holiday is
entered and a schedule does not have the selected
special daily schedule defined, then it reverts back
and use the regular schedule for that day of the
week.
•
Standard Weekly Schedule
- If a daily schedule is
not defined for a day of the week then the control
algorithm searches back in time for the last defined
state change. If no daily schedules are defined, the
output of the schedule is set to Off.
Overlapping Events
The user is allowed to enter overlapping events,
however, the first ON event and first OFF event of out-of-
sequence events is picked up.
Operation When Not Within Programmed Date Range
If the current system date does not fall into any of the
date ranges specified, the schedule control loop is
considered not active. A special value (NO_VALUE) is
written to the output, and TUCOS is set to a maximum
TUCOS value (2 days or 2880 minutes) while TSCOS still
reflects the actual elapsed time since last change of state.
The Master Schedule
NOTE: The Start Time is not the time you wish
for the maintenance override to make a state
transition - it is the time when you want to start
the schedule override.