Future Design MCT-MC 4.3, Руководство пользователя

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MCT-MC
4.3
Appendix - 171 - FDC MCT-MC
i. If the process value has not exceeded the target set point for the ramp step, the time
remaining will be dependent upon the programmed ramp rate and the difference
between the process value and the target set point of the step. If ramp time units are
used, i.e., MM.SS or HH.MM, the ramp rate is calculated by using the difference
between the set point of the previous step and the set point of the current ramp step
divided by the step time to get a rate of change in units/time.
Example: A program is started on step 3 which is a ramp step to -50 in 10 minutes.
The “current control setpoint” (static set point) is chosen as the starting program set
point. If the static set point is 25, the program will begin and start ramping the set point
from 25 to the target set point of -50 over a period of 10 minutes (a ramp rate of
7.5/minute). On power recovery, if the process value is -3, the control set point will be
set to -3.
The program will then begin ramping from -3 to the target set point of -50. The time
remaining for the ramp is then be determined by the programmed ramp rate. If step 1
of the program is a ramp to 50, and step 2 is a soak at 50, the programmed ramp rate
was from step 2 at 50 to step 3 of -50 in 10 minutes. That is a total of 100 over a period
of 10 minutes which is a ramp rate of 10/minute. Since the difference between the
process value and target set point is 47, the time remaining will be 4 minutes and 42
seconds. Thus, the program will continue ramp step 3 from -3 to -50 over a period of
4 minutes and 42 seconds.
Note that when starting on step 1 of a program which is a ramp step, the previous set
point will be the set point as defined by the “setpoint at start of automatic program”
selection.
ii. If the process value has exceeded the target set point for the programmed ramp step,
i.e., the programmed ramp was increasing the set point to 50 and the process value is
>50 or the ramp step was decreasing the set point down to -50 and the process value
is < -50 on power recovery, the time remaining for the step will be the time remaining
at the last save interval. If less than 6 minutes had elapsed into the step at the time of
power loss, the step time will be the original time remaining from the beginning of the
step. If more than 6 minutes into the step, the step will return to the last 6 minute
interval that elapsed (from the beginning of the step) and resume from the time
remaining at that moment the save occurred. The program will then ramp from the
current process value to the target set point of the step over the remaining time.
b. When recovery occurs on a soak step, the time remaining in the step will return to the last save
interval. If less than 6 minutes into the step, the step will resume from the beginning of the
step. If more than 6 minutes into the step, the step will return to the last 6 minute interval that
elapsed (from the beginning of the step) and resume from the time remaining at that moment
the save occurred.
The set point will return to the programmed soak set point, i.e., the set point of the previous
ramp step in the program. If a program is started on a soak step, the set point is defined by
the “setpoint at start of automatic program setting.” However, on recovery, the set point is
defined by the programmed set point which may be different from the original soak set point at
the start of the program.
Example : A program is started on step 2 which is a soak step. The “current process value” is
chosen as the starting program set point. If the process value is 37, the program will begin and
soak at the set point of 37 matching the process value. On power recovery, the set point will
go to the set point defined by the program, so if step 1 of the program is a ramp to 25, the set
point will be 25 on power recovery and the program will finish the remainder of the soak time
with a set point of 25.