Theory & Background

An electric arc is a highly non-linear, variable impedance load. Arc resistance depends on arc length, electrode-to-bath distance, and scrap composition. Short arc (electrode close to bath): low voltage, high current, high power, risk of short-circuit. Long arc (electrode raised): high voltage, low current, low power, risk of arc extinction. The electrode regulation system continuously adjusts electrode position to maintain target arc power by controlling arc impedance.

Components & Requirements

10 components required for this project.

#	Component	Purpose	Qty
1	3-Phase Variac (as EAF power supply)	Variable power input simulating EAF transformer	x1
2	Carbon Graphite Electrodes	Arc discharge electrodes for furnace model	x3
3	Electrode Drive Motors (12V DC)	Raising and lowering electrode positions	x3
4	Current Transformers (large range)	Per-phase arc current measurement	x3
5	DSP Controller (TMS320)	Fast electrode regulation loop	x1
6	L298N H-Bridge Modules	Driving electrode position motors	x3
7	Linear Encoders (position feedback)	Electrode position measurement	x3
8	High-Speed Data Acquisition (10kHz)	Arc current transient capture	x1
9	Thyristor Power Controller	Real power control to arc	x1
10	Flicker Meter (Pst/Plt measurement)	Power quality monitoring	x1

Step-by-Step Implementation

Follow these 3 steps carefully.

1

EAF Arc Characteristics

An electric arc is a highly non-linear, variable impedance load. Arc resistance depends on arc length, electrode-to-bath distance, and scrap composition. Short arc (electrode close to bath): low voltage, high current, high power, risk of short-circuit. Long arc (electrode raised): high voltage, low current, low power, risk of arc extinction. The electrode regulation system continuously adjusts electrode position to maintain target arc power by controlling arc impedance.

2

Electrode Regulation Algorithm

Measure RMS current per phase every half-cycle. Compare with setpoint current. Error drives electrode position: high current → raise electrode (increase arc length and resistance). Low current → lower electrode. PID controller with fast proportional response (P = 0.5) and slow integral (I = 0.01). The derivative term is usually avoided due to noisy current signal. Response time < 100ms is critical — arcs can extinguish in under 50ms.

3

Power Factor and Flicker Management

EAF is one of the worst power quality disturbances — it causes voltage flicker (light intensity fluctuations perceptible to the human eye) due to rapid arc current variations. Flicker is quantified by Pst (short-term severity) and Plt (long-term). Mitigation: static VAR compensator (SVC) or STATCOM connected at the furnace bus to supply reactive power as fast as the arc varies (millisecond response). The SVC tracks arc reactive power demand and compensates in real-time.

Code & Implementation

Core code for eaf_controller.cpp:

eaf_controller.cpp
  C/C++

float setpoint_A = 5.0;  // Target arc current in scaled model float electrode_pos[3] = {50, 50, 50};  float Kp = 0.8, Ki = 0.01; float integral[3] = {0,0,0};  float getArcCurrent(int phase) {   return analogRead(A0 + phase) * (10.0 / 1023.0);  }  void regulateElectrode(int phase, float current) {   float error = setpoint_A - current;   integral[phase] += error * 0.02;    integral[phase] = constrain(integral[phase], -10, 10);   float output = Kp * error + Ki * integral[phase];   electrode_pos[phase] = constrain(electrode_pos[phase] + output, 0, 100);      int motor_cmd = map(electrode_pos[phase], 0, 100, -255, 255);    }  void loop() {   for(int ph=0; ph<3; ph++) {     float I = getArcCurrent(ph);     regulateElectrode(ph, I);   }   delay(20); }

Testing & Troubleshooting

Test Electric Arc Furnace Controller by verifying each subsystem individually before full integration.

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Troubleshooting Tips

Verify power voltages, check ground connections, use serial monitor for debug.

Real-World Applications

*Steel scrap melting and refining

*Ferro-alloy production

*Ladle furnace for secondary metallurgy

*Non-ferrous metal melting

*Silicon and carbide production

*Glass melting furnaces

*Laboratory materials research

*Specialty alloy production

Extensions & Next Steps

Implement advanced scrap preheating integration for energy savings
Add off-gas analysis for chemical control of melt composition
Build a digital twin of furnace thermal model for campaign planning
Implement transformer tap optimization for power factor improvement
Add machine learning for optimal power-on schedule and electrode wear prediction

Interactive Playground

Coming Soon

An interactive simulator will be available here — simulate circuits and run code in-browser without hardware.

Frequently Asked Questions

How much energy does an electric arc furnace consume to produce one ton of steel?

A modern DC EAF producing steel from scrap consumes 300–350 kWh/ton of steel. AC EAF typically 350–400 kWh/ton. Traditional blast furnace (primary steelmaking from iron ore using coal) consumes 2000–2500 kWh equivalent/ton. EAF steelmaking is therefore 5–7× more energy-efficient when using scrap, which is one reason why steel recycling is economically and environmentally superior. EAF also produces significantly lower CO₂ emissions — 0.4–0.6 tons CO₂/ton steel versus 1.8–2.1 tons for blast furnace.

Introduction