Siemens Module B3 manual Setpoint, Setting the PI controller according to Ziegler-Nichols

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Automation and Drives - SCE

Then, the system step response is recorded with the curve plotter from 0 to 100%.

For systems that tend to overshoot, 90% should be assigned as step value.

Setpoint

Turning Point

Tu Tg

System step response for Tu-Tgapproximation

After the inflectional tangent is drawn in the figure, the following values can be read: Tu = 0.7s

Tg = 7s

1.0 * KS = 1.0

The result is KS = 1.0 and the ratio Tg/KS = 7s.

Setting the PI controller according to Ziegler-Nichols

The following controller parameters result with the values Tu-Tgapproximation, and the rules for controller adjustment according to Ziegler-Nichols:

KPR = 9

TN = 2.3s

These controller parameters are transferred to DB41.

Preface Fundamentals Discontinuous Action Controller Controller Block (S)FB41 Setting the System Appendix

T I A Training Document	Page 59 of 64	Module
		B3
Issued: 02/2008		Control Engineering with STEP 7

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Contents Module B3 Automation and Drives SCE Table of Contents Automation and Drives SCE Prerequisites To 3 days Module C To 3 days Module DFrequency Converter at Simatic S7 Learning ObjectivePLC Hardware and software requiredTasks of Control Engineering Fundamentals of Control EngineeringFeedback Variable r Components of a Control LoopControlled Variable Controlling Element Disturbance Variable zSetpoint Value w Comparing ElementDead Time ActuatorControlled System Characteristics Step Function for Examining Controlled Systems ForAutomation and Drives SCE Time constant Proportional Controlled System with a Time DelayControllability of P-Tn systems Proportional Controlled System with Two Time DelaysTu Delay time Tg Transition time Proportional Controlled System with n Time Delays Controlled Systems without Inherent Regulation Types of Controllers Two Position Controllers Hysteresis Switch-On Value Manipulated Variable TimeThree Position Controllers Basic Types of Continuous Controllers Proportional Controllers P-Controller Automation and Drives SCE Integral Action Controllers I- Controller WithController Layout PI ControllersPID Controllers Derivative Action Controllers D-ControllerObjectives for Controller Adjustment 450.85 Digital Controllers DAC Preface Fundamentals YES StructogramExercise Assignment List Symbol Address CommentNetwork Possible Solution for the PLC ProgramD24/AIFillSetpNorm/Norm.value for level setpoint Network 10 Title Task Definition for PID Standard Controller Function Diagram of the control system with a PID controller Description FB 41 ContcUse Exercise Example Automation and Drives SCE Automation and Drives SCE Automation and Drives SCE Automation and Drives SCE Automation and Drives SCE Automation and Drives SCE Automation and Drives SCE Automation and Drives SCE SP INT PLC’ Automation and Drives SCE Automation and Drives SCE Automation and Drives SCE T g Approximation GeneralTu-TgApproximation Setting the PI-Controller according to Ziegler-Nichols For setpoint characteristic MAN Solution of the PLC program Setpoint Setting the PI controller according to Ziegler-NicholsAppendix Diagram of the controller blockComrst Bool False Input Parameters Data Value Range Default Description TypeParameter Data Type Value Range Default Lmnhlm Real Lmnllm Output Parameters Parameter Data Value Range Default Description Type