Product Specification

• Working principle:By connecting a fixed or saturated reactor in series on the primary side of the arc furnace transformer, the reactance value of the circuit is increased to 1.5-2 times the original value. For example, for a common impedance electric arc furnace above 40t/25MVA, the reactance value is about 3.5-4.0mΩ, while that of a high-impedance electric arc furnace can be increased to about 6-8mΩ. This makes it more suitable for long-arc power supply.
• Advantages:
  • Reduced mechanical stress: Due to the reduced current, the electromagnetic force is decreased, and the impact stress and vibration on mechanical equipment components are reduced. The short-circuit current impact on electrical equipment components is also alleviated.
  • Lower power grid interference: It can reduce current fluctuations by 46% and voltage flicker by nearly 30%, thereby reducing the impact and interference on the power grid and reducing flicker.
  • Lower consumption: The reduction in current leads to a decrease in power consumption and electrode consumption.
  • High arc stability: Due to high reactance and low power factor, the arc stability is high.
  • Reduced equipment vibration: It can reduce the tremor caused by the insufficient rigidity of the electrode lifting mechanism.
  
  
• Equipment composition: It mainly includes an electric furnace transformer, short network, electrode lifting device, conductive cross-arm, water-cooled furnace cover, furnace cover lifting and rotating device, furnace body, furnace body tilting device, ladle, tapping car, cooling water system, compressed air system, hydraulic system, automatic feeding system, high-voltage power supply system, low-voltage electrical control system, basic automation, and computer control system.
• Application: As the main equipment in the short-process steelmaking, it is very beneficial for smelting steel grades containing more easily oxidized elements. It can be used to smelt carbon structural steel, various alloy steels, and stainless steel. The raw materials can be cold full scrap steel, part of scrap steel + hot metal, preheated scrap steel, hot-pressed reduced iron, sponge iron, etc.

• Parameters of High Impedance Electric Arc Furnace

  
  
  This document summarizes the core technical parameters of the High Impedance Electric Arc Furnace (HIEAF), divided into four categories: basic rated parameters, key electrical parameters, structural and process parameters, as well as energy consumption and environmental protection indicators. Typical values corresponding to common furnace capacities are provided for direct reference and selection.
  
  

  1. Basic Rated Parameters (Classified by Mainstream Capacity)

  
  
  High-impedance electric arc furnaces are generally distinguished by their nominal capacity, ranging from over ten tons to more than one hundred tons. The matching transformer capacity is strictly matched with the furnace capacity.
  
  

  Nominal Capacity	Rated Transformer Capacity	Applicable Steel Grades	Daily Heat Number
  30t	30～35MVA	Mild steel, low-alloy steel	8～12 heats
  50t	50～60MVA	Mild steel, alloy steel, stainless steel	10～14 heats
  80t	80～90MVA	Alloy steel, stainless steel, special steel	12～16 heats
  100t	100～120MVA	Special steel, high-quality stainless steel	14～18 heats
  150t	150～180MVA	Large-scale short-process steel plants, supporting continuous casting and rolling	16～20 heats

  
  

  Note: Compared with conventional electric arc furnaces, high-impedance furnaces feature more stable arcs and allow long-arc operation, resulting in higher transformer utilization efficiency and faster smelting rhythm.

  
  

  
  

  2. Key Electrical Parameters (Critical Characteristics of High-Impedance Furnaces)

  
  
  These represent the core differences from conventional electric arc furnaces and are the key indicators of high-impedance design.
  
  

  2.1 Short-Circuit Impedance and Series Reactance

  
  
  • Short-circuit impedance of conventional EAF transformers: generally 10%～12%
  • Short-circuit impedance of HIEAF transformers: increased to 16%～20%, and can reach 22% for extra-high-impedance designs
  • Series reactor reactance on the primary side: 1.5 to 2 times the leakage reactance of the furnace transformer. The increased total circuit reactance effectively limits short-circuit impulse current and suppresses voltage flicker.
  
  

  2.2 Rated Voltage Level

  
  
  Common high-voltage incoming voltages include 35kV, 66kV and 110kV. The low-voltage side provides high-current output for furnace operation, with multi-level voltage regulation to meet the requirements of melting, oxidation and reduction stages.
  
  

  2.3 Rated Current and Short-Circuit Current

  
  
  • Rated electrode operating current: increases with capacity, about 25～30kA for a 50t furnace and up to 40～50kA for a 100t furnace.
  • Core advantage of high-impedance design: short-circuit impulse current can be reduced by 30%～40%, greatly mitigating impacts on the power grid, transformer and short network.
  
  

  2.4 Power Factor

  
  
  Due to series reactance, the natural power factor of HIEAF is relatively low, generally 0.75～0.85. It is usually equipped with Static Var Compensator (SVC) or Static Var Generator (SVG). After compensation, the power factor can be improved to above 0.9.
  
  

  3. Electrode and Short Network Parameters

  
  
  Electrodes are core energy-consuming components of electric arc furnaces. HIEAF presents significantly better electrode consumption performance than conventional furnaces.
  
  
  • Electrode Material: Ultra-High Power (UHP) graphite electrodes are widely adopted, featuring oxidation resistance, high temperature resistance and higher allowable current density.
  • Electrode Diameter
    • 30t furnace: Φ350～400mm
    • 50t furnace: Φ450～500mm
    • 80～100t furnace: Φ550～600mm
    • 150t furnace: Φ650～700mm
    
    
  • Electrode Consumption Index: Benefiting from long-arc operation and small current fluctuation, electrode consumption of HIEAF can be controlled at 1.2～1.8 kg/t steel, while that of conventional EAF is generally above 2.0 kg/t steel.
  • Short Network Parameters: The short network adopts large-section water-cooled copper tubes or copper-aluminum composite conductors. Length is minimized and circuit resistance is reduced to lower active loss. For HIEAF, circuit reactance matching is prioritized over simple resistance reduction.
  
  

  4. Structural and Process Operating Parameters

  
  

  4.1 Furnace Structure

  
  
  • Furnace Shell Material: High-strength boiler steel plates such as Q345, lined with refractory materials including magnesia-carbon bricks and alumina-magnesia-carbon bricks.
  • Furnace Cover Type: Full water-cooled truss furnace cover, with high temperature resistance, long service life and adaptability to high-power long-arc working conditions.
  • Tilt Angle: Rated tapping tilt angle is 45°～50°, hydraulically driven with adjustable tilting speed.
  
  

  4.2 Oxygen Supply and Carbon Injection System

  
  
  • Oxygen Supply Mode: Combined-flow oxygen lance and water-cooled oxygen lance, with oxygen pressure of 0.8～1.2MPa. Oxygen flow increases with capacity, reaching 3000～4000Nm³/h for a 100t furnace.
  • Carbon Injection System: Used for foaming slag generation and submerged arc operation. Coordinated with foaming slag, HIEAF can further increase operating voltage and reduce power grid fluctuation.
  
  

  4.3 Smelting Cycle and Temperature

  
  
  • All-scrap smelting cycle: For 50～100t HIEAF, power-on smelting time is 45～60min/heat. Including tapping, patching and charging, the total cycle is 60～80min.
  • Tapping Temperature: Depending on steel grades, 1600～1680℃, with higher temperatures for special steels such as stainless steel.
  
  

  5. Energy Consumption and Environmental Protection Indicators

  
  

  5.1 Power Consumption Index

  
  
  HIEAF achieves higher thermal efficiency via long-arc operation, with better power consumption than conventional EAF.
  
  
  • All cold scrap smelting: 380～420 kWh/t steel
  • With hot metal addition or hot-charged scrap: can be reduced to 320～360 kWh/t steel
  
  

  5.2 Power Grid Interference Indicators

  
  
  • Voltage Flicker (Pst): Reduced by 25%～35% compared with conventional furnaces, making it easier to meet power grid standards for harmonic and flicker limits.
  • Harmonic Suppression: Equipped with reactive power compensation and filtering devices, it can comply with the harmonic limits specified in GB/T 14549.