Mitsubishi Electric FR-A500 Instruction Manual page 147

(2) PID action overview
1) PI action
A combination of proportional control action (P) and integral control action (I) for providing a manipulated
variable in response to deviation and changes with time.
[Operation example for stepped changes of process value]
Note: PI action is the sum of P and I actions.
2) PD action
A combination of proportional control action (P) and differential control action (D) for providing a
manipulated variable in response to deviation speed to improve the transient characteristic.
[Operation example for proportional changes of process value]
Note: PD action is the sum of P and D actions.
3) PID action
The PI action and PD action are combined to utilize the
advantages of both actions for control.
Note: The PID action is the sum of P and I and D actions.
P action
D action
PD action
PID action
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PARAMETERS
Deviation Set point
P action
I action
PI action
Set point
Deviation
Process
value
Time
Time
Time
Set point
Deviation
Process
value
P action
Time
I action
Time
D action
Time
y=at + bt + c
2
Time
Process value
Time
Time
Time