Used in large integrated steel plants for mass production of ordinary carbon steel and high-quality alloy steel.

According to the Chinese national standard GB/T 10067.21-2015, an AC EAF with a rated capacity of 70 tons or more is defined as a "large" furnace. These furnaces almost exclusively operate at Ultra-High Power (UHP) levels to maximize productivity. The HX-100 series is a typical example. The high power input significantly reduces the melting time, achieving a fast tap-to-tap time.

The 100t EAF is a mainstay for large-scale steel production, designed for high efficiency and flexibility, capable of handling 100% scrap or charging with up to 30% pig iron. Modern 100t furnaces often utilize high-impedance technology to stabilize the arc and improve energy efficiency.

1. Power Supply & Control: Equipped with on-load tap changers for voltage regulation and PLC-based control with HMI for fully automatic melting.
2. Oxygen Injection: Typically includes furnace door carbon-oxygen lance and wall-mounted oxygen lances (e.g., 3+1 configuration) to supply chemical energy, significantly reducing power consumption and tap-to-tap time.
3. Bottom Tapping: EBT system with a hot heel of approximately 15-20 tons, allowing for faster tapping and improved slag control.
4. Continuous Scrap Preheating: Often configured with a continuous feeding system that preheats scrap using off-gas, leading to significant energy savings .
5. Advanced Welding & Manufacturing: To withstand extreme temperatures (over 1600°C) and stress, critical components like the furnace shell use full-penetration welding and stress relief annealing to ensure "zero defect" delivery and longevity.

6. Modular Assembly: For large components like the roof lifting and rotating device, a modular "pre-assembly" strategy is often employed to overcome logistical challenges.