Filter
Top Products
214
Special operation and frequency control
3)PID action
4)Reverse operation
Increases the manipulated variable (output frequency) if deviation X = (set point - measured value) is positive, and
decreases the manipulated variable if deviation is negative.
5)Forward action
Increases the manipulated variable (output frequency) if deviation X = (set point - measured value) is negative, and
decreases the manipulated variable if deviation is positive.
Relationships between deviation and manipulated variable (output frequency)
The PI action and PD action are combined to utilize the advantages of both
actions for control.
(Note) PID action is the sum of P, I and D actions.
Deviation
Positive Negative
Reverse action
Forward action
Deviation
y=at
2
+bt+c
Set point
PID
action
D
action
P
action
I
action
Time
Time
Time
Time
Measured value
Set point
X>0
X<0
Feedback signal
(measured value)
+
-
[Heating]
Deviation
Set point
Measured value
Decrease
Cold
Increase
Hot
Set point
X>0
X<0
Feedback signal
(measured value)
+
-
[Cooling]
Deviation
Set point
Measured value
Too cold
Decrease
Hot
Increase