With the development of PLC technology, PLC system applications in industrial enterprises more and more widely. New iron and steel enterprises has been widely used to achieve electrical and automation PLC control. BOF process is relatively complex, multi-parameter testing, equipment moves frequently. Accuracy of detection parameters, automatic high and low level, directly related to the level of quality and yield of molten steel. Therefore, we must have a test accurate, timely, high level of automation control systems to stable production, to meet the needs of enterprise survival and development. This paper Luannan Huarui 65t converter Electrical Construction, for example, describes the general PLC control system design method and should be E4; mso-ascii-font-family: Times New Roman ; mso-hansi-font-family: Times New Roman "> converter, electronic control, instrumentation, computer “ Three ” control system all-digital, full distribution, network system architecture. control system is the core of modern production, it will control and management from the molten iron, scrap steel, the factory started by iron treatment, converter blowing, steel, water treatment, into the continuous casting So far the steel plant s production process. workshop production line automatic control system has the basic automation and process control of the two computer control system. Automation system control: basic automation system control. Including: oxygen gun down function, converter tilting function, raw material unloading function, gas recovery functions. Process monitoring level computer systems of control: The whole production line of production management, including production planning, production report, Shi Shi data and historical data stored for viewing, printing, production line electrical equipment fault diagnosis, alarm function, Juyouwuliao automatic tracking Gongneng . The level of control automation systems: using the computer to achieve full range of automatic control, -Family: Arial; mso-ascii-font-family: Times New Roman ; mso-hansi-font-family: Times New Roman "> workshop production management, quality control, basic automation, local area network used across the board. Basic automation level (L1 level) of the main functions: storage of various control forms; logic and sequence control; cascade speed control; unit automatically adjust and set; linkage fault protection; hydraulic, lubrication system control; print control. (2) Automatic Control System Components Converter control system uses 4 sets SIMATICS7-400PLC main station of the respective converter body control, bulk material control, flue gas purification and control of evaporative cooling. The main host configuration frame, extending rack, power systems, New Roman "> CPU, interface module, communication module, as well as digital and analog input / output module. 4 sets of master data communication between the Ethernet completed. Master PLC converter body: the master PLC converter main body of the door complete the blast furnace tilting the furnace body movements and operations, after the tilting furnace and a steel ladle car, slag truck operators, lift operators and oxygen hoods of guns lifting operation and oxygen lance positioning control, oxygen gun for gun traverse operation, the material weighing and feeding operations such as real-time data collection and monitoring, overrun and incident alarm. PLC via Ethernet and operation of real-time data transmission between stations, from the man-machine interface to complete the production process monitoring. Mainframe: mainframe, including power supply, CPU New Roman ; mso-hansi-font-family: Times New Roman "> power should use twisted pair wire > 2mm. If you choose expansion unit, the host and expansion unit to share a single switch, which also power or power failure; PLC ground terminal is generally not grounded. If you need ground, should take special earth. according to the standard wire 2mm2, grounding resistance ≤ 4 ohm, ground point should be close to PLC; input signal length should not exceed 30m. input, output alignment to be separated, and with the power line to keep distance of more than 200mm; PLC if installed directly on the metal plate, the bottom layer should be insulating pad to prevent interference; emergency stop line should PLC ; Mso-hansi-font-family: Times New Roman "> output circuit of the external off; debugging, the programmer can not hot plug cable, to prevent damage to the device; PLC power supply to external load and increase speed fuse protection . 4, anti-interference measures PLC strong anti-interference ability, but the external disturbances, such as inverter, refining furnace, etc., should also set up some anti-interference measures: PLC direct grounding system grounding; Ground with 800 × 800 × 5 copper grounding, grounding cable with cross section 70mm2 More shares than copper wire,93; mso-ascii-font-family: Times New Roman ; mso-hansi-font-family: Times New Roman "> system grounding resistance of less than 4 Ω; to cable and other cables completely separate, individual through pipe laying; order to reduce the power radiated electromagnetic interference, signal to the PLC site template signal line shielded cable should be taken, and different types of signals transmitted by different cable, and layered laying, is strictly prohibited to use the same cable in different power supply wires, transmit signals to reduce electromagnetic interference; Cable Road as far as possible away from the transducer, refining furnaces and other sources of interference. 5, installation requirements (1) Installation location requirements PLC installation must be chosen for the region, the standard PLC electrical housings. Or near the control panel in order to avoid potential interference with electrical installations, Equipment should meet the following conditions. Dust with a closed box; and high-frequency equipment installation together, the jacket must be grounded; not to PLC installed above the heat source; not to PLC and the high-voltage equipment installed within the same casing; as far as possible away from power lines and power lines; vertically PLC, to ensure maximum air can flow, while preventing dirt from falling into the machine pass lane. (2) Installation environment requirements Environmental Requirements: 0 ??? ~ 55 ???, relative humidity: 35%ew Roman ">, and can greatly reduce the project investment costs. in the practical application of business performance that fully meet the requirements of production requirements, is a high cost performance converter PLC configuration.