Nowadays, many enterprises still work on electric arc furnaces (EAF), which were designed during the Soviet Union. The metal structures of these furnaces were manufactured with multiple supplies and therefore, even after so many years, they continue to work quite reliably. However, the drive and control systems of these furnaces have already exhausted their resources are constantly failing, and the necessary spare parts for their repair cannot be found, as they have not been produced for a long time.
The downtime caused by the constant failure of drives and control systems, as well as the maintenance of such furnaces, inevitably lead to an increase in the production cost.
One of the most cost-effective measures to reduce the cost of metallurgical production is to increase the efficiency of operation of existing EAF by equipping them with a modern automatic control system built on the basis of modern control tools. In addition, there is a need to use modern control laws for melting process, as well as a multi-level automation system with advanced subsystems for visualization, diagnostics, statistical processing and documentation.
Modernization of the control system helps to optimize and speed up the technical process, thereby increasing the volume and quality of products. At the same time, the equipment is getting upgraded without unnecessary financial costs.
Modernization means complete replacement of the control system and drives, and, if necessary, repair of the mechanical part of the equipment.
Our automated control system (ACS ‘OPTIM’) is built on the basis of an industrial controller. It is designed for:
- control electrode-positioning drives of the furnace in order to automatically maintain the set current value (power);
- implementation of technological protections and furnace interlocks;
- control of high-voltage vacuum load break switch;
- regular temperature control of water-cooled circuits of electric furnace;
- control of melting mode indicators;
- control of furnace mechanisms.
ACS consists of the following subsystems:
- Automatic melting mode regulator;
- Furnace control system;
- Heat control system for water-cooled circuits of electric furnace.
ACS ‘OPTIM’ automatic melting mode controller provides:
- maintenance of current (power) in 'automatic' mode independently for each electrode;
- automatic elimination of short circuits in 'automatic' mode.
The furnace control system provides:
- furnace mechanisms;
- high-voltage switch:
Blocking the switch on when there are inhibiting signals from other systems. Switching on is carried out from the smelter's remote control only after a warning sound signal is given. Automatic switch off when high-voltage vacuum load break switch, furnace transformer and heat control system protection is triggered;
- manual and automatic control of the electrode-positioning drives:
In automatic mode, control is carried out by commands from the automatic mode controller; in manual mode, it is carried out from the control panel of the smelter with the help of switches;
- switch of the furnace transformer voltage stages from the control panel of the smelter.
- temperatures and flows in cooled furnace circuits;
- furnace nodes positions;
- melting mode indicators;
- limit and emergency modes of operation.
Displaying the following options on the console:
- 'A' phase electrode current;
- 'B' phase electrode current;
- 'C' phase electrode current;
- 'A' phase electrode voltage;
- 'B' phase electrode voltage;
- 'C' phase electrode voltage;
- active power of furnace;
- stage number of furnace transformer;
- status of the high-voltage switch (on/off/ emergency shutdown);
- triggering of poisition switches;
- position of the furnace;
- cooling water temperature by cooling circuits;
- melting time.
ACS package includes:
- control cabinet;
- stationary operator's console;
- steelworker's console;
- a set of temperature and flow sensors;
- сable products for control system disconnection.
Works on furnace automation are carried out in several stages:
- Development stage：
At this stage, the ACS ‘OPTIM’ system ‘links’ to a specific furnace. We are working on ideas for installation of electrical equipment, planning cable-wiring paths, drawing up specifications of equipment and materials, and purchasing the materials.
- Production stage:
We assemble cabinets, consoles, make their pre-debugging.
- Control System Replacement stage:
We dismantle the old control system, prepare the room for installation of ACS ‘OPTIM’, then install the new control system and prepare it for commissioning.
- Commissioning stage:
After the installation work is completed, we carry out the necessary commissioning. After commissioning, we perform control maintenance of the furnace operation for 2 days.
Operational documentation set:
- list of documents;
- external wiring diagram;
- wiring schematic;
- control system operating manual;
- instructions and passports for components used in the system.
The documentation is transmitted to the Customer in 2 copies, as well as in an electronic version on a CD together with backup copies of controller programs and converter settings.
To receive technical and commercial proposal, please download and fill in the questionnaire and send it to us by e-mail: email@example.comThe following are pictures of the condition of EAF-3 furnace equipment before and after the modernization works.