2. COMMUNICATION IDENTIFIER LIST
IMSRM07-E6
21
Output limiter
This is the function which restricts the high and low limits of Manipulated output values (MV).
The manipulated output value
in this range is not output.
The manipulated output value
in this range is not output.
Manipulated output value (MV)
100 %
0 %
Output limiter high
Output limiter low
Time
Manipulated output value (MV)
Output change rate limiter
The output change rate limiter limits the variation of Manipulated output (MV) per second.
This function is suitable for an application in which a sudden MV change is not acceptable.
[The output change rate limiter is effective
.]
•
The MV reaches 100 % when the power is turned on to the controller and such a sudden output
change is not acceptable in the application.
•
A sudden output change occurs at the SV change and it is not acceptable in the application.
The output changes at specific rates set by output change rate limiter (up) even under the situations
where a sudden output change would occur without output change rate limiter function. There is also
independent output change rate limiter (down).
If the output change rate is set smaller, it will cause slow control response and affect
Derivative action.
When the output change rate limiter is used, you may not be able to obtain appropriate PID
constants by autotuning.
The output change rate limiter is particularly effective when a sudden MV change may create
uncontrollable situation cause a large current flow. Also, it is very effective current output or
voltage output is used as control output.
Output limiter high
100.0 %
Output limiter low
0.0 %
Manipulated output (MV)
Manipulated output (MV)
Sudden
variation of
output
When the output change rate limiter is disabled
MV
MV
0.0 to
100.0 % of
manipulated
output
1 second
Set the amount of increase given to the
operation output in the percentage of
manipulated output for each second.
Sudden change in the output when power on, set value change or disturbance
