Distributed Control System (DCS)

A Distributed Control System (DCS) is a computerized control system for a process or plant, in which autonomous controllers are distributed throughout the system, but there is central operator supervisory control. This is in contrast to non-distributed control systems that use centralized controllers; either discrete controllers located at a central control room or within a central computer. The DCS concept increases reliability and reduces installation costs by localizing control functions near the process plant, but enables monitoring and supervisory control of the process remotely.

               DCS first emerged in large, high value, safety critical process industries, and were attractive because the DCS manufacturer would supply both the local control level and central supervisory equipment as an integrated package, thus reducing design integration risk. Today the functionality of SCADA and DCS systems are very similar, but DCS tends to be used on large continuous process plants where high reliability and security is important, and the control room is not geographically remote.

DCS Advantages -

  • Data presentation is in a systematic format enabling easy comparison of various parameters and taking decision by a printer.
  • Logging of data is done by a printer thereby eliminating human error.
  • It is possible to control through dynamic graphic.
  • Operator’s action can be logged, thereby eliminating confusion.
  • The alarm system can be regrouped.
  • Complex computations, analysis, etc. can be carried out easily.
  • Management information can be generated at regular intervals.
  • The super-imposed trends helps in the analysis of plant parameters and
  • Hardcopy gives the actual dynamic printout at a particular instant.
  • The controlling software used is very simple and the application is readily The software changed in one unit has no impact on other units and hence the system becomes very flexible. User’s risk in software is minimum.