Mitsubishi Electric 800 Series Instruction Manual page 342

[Example of action when the measured value changes proportionately]
Set point
Deviation
Measured value
P action
Time
D action
Time
PD
action
Time
(Note) PD action is the result of P and D actions being added together.
 PID action
PID action is a combination of PI and PD action, which enables control that incorporates the respective strengths of these
actions.
Set point
Deviation
Measured value
P action
Time
I action
Time
D action
Time
PID action
Time
(Note) PID action is the result of all P, I and D actions being added together.
 Reverse action
When deviation X = (set point - measured value) is a plus value, the manipulated amount (output frequency) is increased, and
when the deviation is a minus value, the manipulated amount is decreased.
Set
point
Feedback signal
(measured value)
 Forward action
When deviation X = (set point - measured value) is a minus value, the manipulated amount (output frequency) is increased,
and when the deviation is a plus value, the manipulated amount is decreased.
Set
point
(measured value)
Relationship between deviation and manipulated amount (output frequency)
PID action setting
Plus
Reverse action
Forward action
2
y = at + bt + c
[Heating]
+ X>0
Cold
Hot
X<0
-
[Cooling]
X>0
+
Too cold
Hot
X<0
-
Feedback signal
Deviation
Minus
Deviation
Increase
Decrease
Measured value
Measured value
Decrease
Increase
Deviation
Set point
Set point
14.(A) Application Parameters
14.4 PID control
11
12
13
14
15
16
17
18
19
20
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