User's Manual

Automation and Drives - SCE
T I A Training Document Page 7 of 64 Module
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
Element
Controll
g
.
Element
Actuator
Final Ctrl. Elem.
+ System
Setpoint
Temperature
Measuring
Device
Preface Fundamentals Discontinuous Action Controller Controller Block (S)FB41 Setting the System Appendix
B3
Issued: 02/2008 Control Engineering with STEP 7