Siemens Module B3 manual Fundamentals of Control Engineering, Tasks of Control Engineering

Automation and Drives - SCE

2. FUNDAMENTALS OF CONTROL ENGINEERING

2.1 Tasks of Control Engineering

"Closed loop control is a process where the value of a variable is established and maintained continuously through intervention based on measurements of this variable. This creates a sequence that takes place in a controlled loop -the closed loop- because the process is executed based on measurements of a variable that is in turn influenced by itself.“

The variable to be controlled is measured continuously and compared with another specified variable of the same kind. Depending on the result of this comparison, the control process adjusts the variable to be controlled to the specified variable.

Diagram of a Control System

Comparing		Actuator	Final Ctrl. Elem.
	Controllg.
Element	Element		+ System

Setpoint Temperature

Measuring Device

	Preface	Fundamentals	Discontinuous Action Controller Controller Block (S)FB41	Setting the System Appendix
	T I A Training Document		Page 7 of 64	Module
				B3
Issued: 02/2008				Control Engineering with STEP 7