YME Engineering Course

A. INTRODUCTION TO PROCESS CONTROL SYSTEM
A.3. PROCESS CONTROL SYSTEMS
To perform temperature control as discussed before, a control system ( a device
to perform the control computation) is required. There are many control systems
available, which are generally classified into analog, and digital control system.
Analog Control System
Control device that makes a control computation with analog signals (e.g.
Voltage) using operational amplifiers etc. I this case sequence control is not
available.
Digital Control System
Control device that makes control computation with digital values using a
processor (processing unit). Not only the feedback and feed forward controls
(called DDC-Direct digital controls collectively) but also sequential control is
available.
Signal 1 to 5 V DC
Conversion +
Operational Amplifier
4 to 20 mA DC
-
I/P
Figure: Overview of Analog Control System
YME Training Center
A-3
CS3KR3-ENG 1 ST Edition Jan 2002