Plant distributed control system (DCS)

The above-mentioned DCS systems MECO uses support at least one or more types of Field Bus technologies such as Foundation Field Bus, DeviceNet and Profibus and are able to connect to them. By using the Field Bus, a great number of Instruments/Actuators can be connected to the controllers using a single interface cable resulting in substantial reduction in cable use.

At mid-level are the controllers; each controller is in charge of a part of the plant and is usually named after that part. The controllers are connected to each other and the higher level through a communication network. A redundant controller provides the network with a form of backup or fail-safe.

The communication network between the controllers is called Plant Bus and uses optical fiber as a physical interface for its high speed and noise immunity.

The communication method is Ehternet with standard specification of IEEE802.3, which is used extensively by combining twisted paired cables to connect the network endpoints and optical fiber for the site backbone connections.

The DCS system design and engineering software is installed on a computer called ES, or engineering station. ES runs all system engineering operations, including downloading the software in controllers, modifying program logic, and making corrections and changes to the monitoring system graphic pages. ES is installed in the power plant central control room and is connected to both system buses including Terminal Bus and Plant Bus.

An OT, or operating station, is operators’ workstation. On these computers, graphic pages are loaded in runtime (which is not editable). The terminal points are linked to the controllers via a server. Operators can view process values ​​on these systems or send control commands to controllers through operating stations.