PARAMETERS
136
4) Reverse action
Increases the manipulated variable (output frequency) if deviation X = (set point -
process value) is positive, and decreases the manipulated variable if deviation is
negative.
Set point
X>0
X<0
Feedback signal
(Process value)
+
-
[Heating]
Deviation
Set point
Process value
Cold up
Hot down
5) Forward action
Increases the manipulated variable (output frequency) if deviation X = (set point -
process value) is negative, and decreases the manipulated variable if deviation is
positive.
+
-
[Cooling]
Set point
X>0
X<0
Feedback signal
(Process value)
Process value
Set point
Deviation
Too cold down
Hot up
Relationships between deviation and manipulated variable (output frequency)
Deviation
Positive
Negative
Reverse
action
)
*
Forward
action
*
)
