User`s manual

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MELSEC-Q
1 OVERVIEW
1.4.2 Integral operation (I operation)
This section explains the control method using integral operation.
(1) Integral operation is the operation that continuously changes the manipulated value to
eliminate deviation when there is deviation.
This operation can eliminate the offset that occurs during control performed by a proportional
operation.
(2) The time from when a deviation occurs until the manipulated value of the integral operation
reaches the manipulated value of the proportional operation in the integral operation is called
integral time (T
I
).
(a) Increasing the integral time decreases the effect of integration.
(It will take time to stabilize.)
(b) Decreasing the integral time increases the effect of integration.
However, since the integral operation will be stronger, hunting may become greater.
(3) The integral operation when the deviation is a constant value stepped response is shown in
Fig. 1.4.
K DV
DV
T
I
Time
Manipulated value
Deviation
Time
Proportional operation integral operation manipulated value
Integral operation manipulated value
Manipulated value in the proportional operation
P
Fig. 1.4 Integral operation when the deviation is a constant
(4) The integral operation is used as the PI operation that is combined with the proportional
operation or as the PID operation that is combined with the proportional operation and the
derivative operation.
Control cannot be carried out by merely performing the integral operation.