Ny-Series Instructions Reference Manual (W560 - Omron NY532-5400 Reference Manual

One of the parameters for the integral action is the integration time. This is the time for the manipu-
lated variable from the integral action to equal the manipulated variable from the proportional action
when a stepwise deviation occurs. The shorter the integration time is, the stronger the integral
action is. A short integration time reduces the time for the offset to reach 0, but it can also cause
hunting.
Stepwise response
Deviation 0
Manipulated
variable
0
 Derivative Action (D)
If the proportional and integral actions are used together, the offset will reach 0 and the process
value will reach the set point. However, if disturbance causes the process value to change quickly,
time is required to restore the original state. The derivative action functions to quickly return the pro-
cess value to the set point when there is a disturbance. The derivative action differentiates the devi-
ation on the time axis and then increases the absolute value of the manipulated variable in
proportion to the result. In other words, the larger the change in the process value is, the larger the
absolute value of the manipulated variable for the derivative action is. The changes in the manipu-
lated variable for the derivative action when a deviation occurs in stepwise fashion are shown below.
The changes in the manipulated variable when the derivative and proportional actions are combined
are also shown.
Manipulated Variable for Derivative Action
Deviation
Stepwise response
0
Manipulated
variable
0
One of the parameters for the derivative action is the derivative time. This is the time for the manip-
ulated variable from the derivative action to equal the manipulated variable from the proportional
action when a ramp deviation occurs. The longer the derivative time is, the stronger the derivative
action is. A long derivative time provides a rapid response to disturbances, but it can also cause
hunting.
Deviation
Ramp response
0
Manipulated
variable
0

NY-series Instructions Reference Manual (W560)

Time
Proportional and integral actions
Integral action only
Proportional action only
Integration time
Time
Time
Time
Time
Derivative time
Time
2 Instruction Descriptions
Manipulated Variable for Derivative and
Proportional Actions Together
Deviation
Stepwise response
0
Manipulated
variable
0
Proportional action only
Derivative action only
Proportional and derivative actions
Proportional action
Derivative action
2
Time
Proportional and
derivative actions
Time
2-673