SAT Ltd. specializes in development of DCS automation systems based on Programmable Logic Controllers (PLC) and Operator Stations.
Generally in SAT's systems the latest version of SIEMENS PLC SIMATIC S7 are being used, and the list of PLC's is as follows:
- SIMATIC S7-200, S7-300, S7-400 - SIEMENS, DE;
- C200HS - OMRON, JP;
- Procon 256 - CNIKA, BG;
- Sigma 3x16 - SAT GROUP, BG
To satisfy our Clients' requirements, SAT developed automated decentralized systems with different type of remote boxes placed close to the equipment and connected to the main PLC Process Station by Profibus DP communication.
For these systems SAT elaborated different type of standard "Distributed Motor Control Centers" (DMC), incl. all necessary commutation equipment (circuit breakers, contactors, relays) and remote PLC input/output modules of the Process Station.
There were developed also standard "Distributed Input/Output" Boxes and "Distributed equipment Control" Boxes (DIO and DEC), to connect all signals from field instruments and equipment.
The Plant Control System normally arrange so as to allow independent control of Each Department. The Separate Process Stations of the departments are connected in a common network by Industrial Ethernet (Process Level of the Control System).
The Operator Station (based on standard PC) must provide the "Human-Machine" communication to the processes. The plant control system normally includes two Redundant Servers with a common program for the Project, Engineering Station and a number of Client Operator Stations and printers connected via Industrial Ethernet in a common network (Operator Level). All these equipment are normally placed in Central Control Room (CCR) of the Plant. The Redundant Servers communicate with Department's Process Stations via another Industrial Ethernet network by using Optical cables and accessories.
According to the client requirements were developed centralized automated systems by using a MCC type of control, distributed (DMC concept) or mixing systems (partially DMC, partially a MCC structure) for Plant control.
The practice shows that distributed (DMC) and mixed control systems are more comfortable for installation and maintenance and cheaper than MCC type systems.
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