Today much more than half of the total world steel is produced in electric arc furnaces. As solutions providers for Steel-melting Plants, Ingeteam Power Technology, Industrial Systems Division, has a great expertise and many references supporting our knowledge in this area.
Broadly speaking, for medium and high rate production, we have two main types of electric melting furnaces:
- One-electrode furnace, operating in the DC mode; with the electrode forming the cathode and the bottom of the furnace forming the anode.
- Three-electrode furnace, operating in the AC mode; the electrodes normally working into a three-phase electrical circuit and usually placed on the vertices of an equilateral triangle in around the furnace.
Our automation system comprise functions covering the electrode regulation system as well as the control of all the auxiliary elements of the furnace which is carried out by means of a software in a dedicated PLC, which is complemented by an HMI operation and display system which allows the parameterization and process monitoring of the whole facility, including:
Control of the EAF transformer HV primary circuit:
o Voltage, current measurement & counting (kWh meter / kVARh meter),
o Incoming isolator and earthing switch status,
o Vacuum Circuit breaker and disconnectors switches status,
o Protection and trip relays status: overcurrent, under-voltage,
- Reactor prior to power transformer, monitoring and tap on-load changer control,
- EAF transformer, monitoring (Buchholz relay, oil liquid level, oil flow indication, status of oil circulating pump, oil to water heat exchanger status, tap changer status & control,
- Voltage and current measurements in secondary circuit, arranged in equilateral triangle to get uniform reactance in all three phases for symmetrical power input,
- Furnace water cooling, temperature & flow monitoring: roof, walls,
Electrical water cooled parts, temperature & flow monitoring:
o bus bar up to Transformer-room,
o flexible LV cables,
o power conducting arms to electrodes,
- Control of main hydraulic equipment for furnace’s movements,
Control of furnace’s movements, such as:
o Roof and superstructure: hood, roof,
o Furnace tilting, degrees indicated (tapping & de-slagging),
o Electrodes shifting and clamping,
o Gate opening for sampling lances, additives, etc.
o Slag door,
- Electrode regulation & dynamic associated strategies: Control Consumption of Electrodes, by Hot Spot, by Control Power Input, by Automatic gain control kP,
o Melting cycles,
o Electric energy requirement calculation,
o Chemical energy calculation via burners and oxygen blow,
- Production Tracking and Level 2 interface,
- Interfaces with: oxygen lances-manipulator, burners system, sampling lances, temperature measuring equipment, carbon injection device, Argon bubbling station, etc.,
- Status of ladle car: weight, data and position where placed,
- Sequencing & interlocking -safety logics-. Emergency operation,