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SARCWISE® – Digital Furnace Controller

SARCWISE® is SARRALLE's digital feeder: a power supply system designed to transform Electric Arc Furnace (EAF) operations. Built on advanced power electronics, it delivers grid stability, instant power control and minimal disturbances while optimising energy efficiency and reducing operational costs.

Drawing on over 60 years of experience in steelmaking applications, SARRALLE has invested extensively in the development of this new digital feeder and its electrode regulation system. SARCWISE® consolidates deep regulatory know-how with advanced digital control algorithms, high-speed real-time signal acquisition, closed-loop electrode positioning and industrial-grade digital hardware, ensuring stable arc control, optimised electrical performance and reliable operation in modern EAF and LF furnaces.

The system is based on a back-to-back AC-DC-AC or AC-DC architecture with a high-capacity DC link that decouples the furnace from the grid. This decoupling allows voltage, current and frequency to be adjusted in real time — with operating frequencies of up to 70 Hz — minimising perturbations on the network and giving the operator a level of control that is not achievable with conventional supply schemes.

SARCWISE® is delivered in 40-ft ISO containers as plug-and-play 80 MW units, and can be scaled to 160 MW, 240 MW, 320 MW and beyond by adding units in parallel, adapting to any furnace size. Installation time is under 72 hours.

Because the furnace is fed through the converter, the electrical installation is considerably simplified: the existing furnace transformer can be reused or replaced by a traditional power transformer, no reactor is required, no furnace breaker is required, and only minimum taps (±5%) are needed.

In a world shifting towards decarbonisation and grid stability, SARCWISE® offers a high-quality, cost-effective solution for steel producers seeking to optimise OPEX while meeting stringent grid requirements.

 

Technology

 

Technology Advantages:

  • Energy Savings: 15-20% reduction in energy consumption.
  • Electrode Savings: 15-18% reduction in electrode consumption.
  • Power-On Time: 12% reduction.
  • Tap Changes: more than 50% fewer tap changes.
  • Modular Scalability: plug-and-play 80 MW units (80 / 160 / 240 / 320+ MW) in parallel containers.
  • Advanced Digital Control: real-time adjustment of voltage, current and frequency, up to 70 Hz.
  • Grid Decoupling: back-to-back architecture with a high-capacity DC link.
  • Simplified Installation: no reactor and no furnace breaker required, minimum taps (±5%).
  • Transformer Flexibility: the existing furnace transformer can be reused, or a traditional power transformer installed.
  • Reduced Maintenance: fewer moving parts subject to wear.
  • Fast Deployment: 40-ft ISO container, plug-and-play, installed in under 72 hours.

Power Quality (IEC/IEEE Compliant):

  • Flicker (Pst): reduction of more than 14 times.
  • Harmonics (THDi at grid): below 1.5%.
  • Power Factor: above 0.99, reducing reactive power demand.
  • Phase Unbalance: below 0.5%, preventing equipment wear and inefficiency.
  • Infraharmonics: below 0.2%, for smoother furnace operation.

 

SARCON® - Electrode Regulation

 

SARCON® is SARRALLE's furnace regulation system, available for both AC and DC furnaces, with current control, impedance control and frequency control.

Functionalities:

  • Constant admittance and current regulation modes.
  • Up to 8 different adjustable dynamic PID.
  • Short-circuit and isolation body assistance.
  • Heat historic: allows the user to consult the data of every heat through different graphics and displays.
  • Up to 5 power profiles, with 6 setpoint configurations working in current mode and admittance mode (I/V).
  • Up to 5 different speed modes.
  • Adjustable dead band and offset for servo valves.
  • A.S.P.I. (Arc Stable Power Increment).

 

Technical Specifications

 

Architecture Back-to-back AC-DC-AC, hybrid MMC + IGBT
Power per unit 80 MVA (96 MVA overload, 30 min)
Scalability 80 / 160 / 240 / 320+ MW (parallel containers)
Deployment 40-ft ISO container, plug-and-play, installation in under 72 h
Input (grid) 11-36 kV AC (±10%)
Output (EAF) AC 200-1,200 V AC, 10-70 Hz
Output (EAF) DC 1,200 V DC
Efficiency > 98.5%
DC link 2.2-3.6 kV, 50 MJ energy buffer
Cooling Closed liquid, redundant, IP55
Redundancy N+2 submodule, hot-swap

 

Scope of Supply

MV Equipment (optional):

  • Disconnectors.
  • Voltage transformer.
  • Current transformer.
  • Surge protection.

Power Transformer (optional):

  • Possibility of reusing the existing furnace transformer.
  • Or installation of a traditional power transformer.

SARCWISE®:

  • SARRALLE converter in containers.

LV Equipment:

  • AC or DC voltage measurement equipment.
  • AC or DC current measurement equipment.

 

Typical Configuration

 

The SARCWISE® converter and the SARCON® regulation system integrate with the plant Level 2 and the EAF PLC through Profinet, ModBus TCP/IP, S7 Connect and hardwired signals, with RIO units distributed across the main pulpit, the gantry, the hydraulic group and the MV EAF cabinet.