LS Industrial Systems SV-iS7 PLC User Manual

Chapter 6 Usage of Various Functions
6-10
(c) Derivative operation (D action)
① When a deviation occurs, due to alteration of SV or external disturbances, D action
restrains the changes of the deviation by producing MV which is proportioned with the
change velocity (a velocity whose deviation changes at every constant interval) in order to
eliminate the deviation.
② D action gives quick response to control action and has an effect to reduce swiftly the
deviation by applying a large control action (in the direction that the deviation will be
eliminated) at the earlier time that the deviation occurs.
③ D action can prevent the large changes of control object due to external conditions.
④ The period of time from when the deviation has occurred to when the MV of D action
becomes the MV of P action is called derivative time and is represented as Td.
⑤ The D action when a constant deviation occurred is shown as Fig. 7.6
Fig. 7.6 Derivative action with a constant deviation

LS Industrial Systems SV-iS7 PLC Specifications

General

Brand	LS Industrial Systems
Model	SV-iS7 PLC
Category	Computer Hardware
Language	English