Furnace Transformer Manufacturer in India: What Industries Need to Know Before Buying
rc furnaces are among the most electrically demanding pieces of equipment in the world. Whether you are operating a steel plant, a foundry, a ferro-alloy facility, or an induction heating line, the transformer at the heart of your furnace installation is the single most critical component between your power supply and your production output.
Get it right, and your furnace runs efficiently, consistently, and safely. Get it wrong, and you face unplanned downtime, costly transformer failures, and a supplier relationship that leaves you scrambling for replacements.
This guide is written for plant engineers, electrical consultants, and procurement managers who need to understand what furnace transformers are, how they differ from standard power and distribution transformers, what specifications matter most, and how to identify the right manufacturer in India.
Quick answer: A furnace transformer is a custom-designed, high-current, low-voltage transformer built to withstand the extreme electrical stresses of arc furnace operations. When sourcing a furnace transformer manufacturer in India, prioritise BIS certification, in-house testing capability, and proven experience supplying to industrial and metallurgical applications.
What Is a Furnace Transformer?
A furnace transformer — also called an arc furnace transformer or electric arc furnace (EAF) transformer — is a specially designed step-down transformer that supplies very high currents at relatively low voltages to an electric arc furnace. Unlike standard distribution or power transformers, furnace transformers operate under continuous, rapidly fluctuating loads caused by the arc striking, stabilising, and extinguishing cycle inside the furnace.
Key operating characteristics that define furnace transformers:
Very high secondary current (often thousands of amperes at low voltages of 100 V to 1,000 V)
Ability to withstand severe electrical stresses — voltage dips, arc flicker, short circuits
Robust thermal design to handle continuous high-load operation
Multiple secondary voltage taps for precise heat control at different stages of the melting process
Heavy-duty windings using flat copper conductors or transposed cable for superior current-carrying capacity and mechanical strength
Because of these unique requirements, furnace transformers cannot be sourced as off-the-shelf catalogue products. They are always custom-engineered to the specific capacity, voltage ratio, tap range, duty cycle, and environmental conditions of the installation.
Types of Furnace Transformers and Their Applications
1. Electric Arc Furnace (EAF) transformers
Used in steelmaking and metal recycling plants. The transformer supplies three-phase alternating current to graphite electrodes that create an arc to melt scrap metal. EAF transformers are typically rated from a few MVA up to 150 MVA or more for large steel mills. ETT's furnace transformers serve EAF applications in India's growing secondary steel sector.
2. Ladle furnace transformers
Ladle furnace (LF) transformers are used in secondary metallurgy for refining molten steel. They operate at lower power levels than EAF transformers but demand equally precise voltage control to achieve the precise temperature and chemical composition targets required for high-quality steel grades.
3. Submerged arc furnace (SAF) transformers
Used in ferro-alloy, ferrosilicon, calcium carbide, and phosphorus production. SAF transformers supply very high currents at low voltages to submerged electrodes buried in a charge mix. They typically operate at low power factors and require careful design to manage harmonic distortion.
4. Induction furnace transformers
Induction furnace transformers step down supply voltage to feed medium-frequency power conversion equipment that drives induction coils. Widely used in foundries, casting shops, and small-to-mid size steel producers, induction furnaces require transformers with excellent regulation and low leakage reactance.
Critical Specifications to Define Before Purchasing
Furnace transformer procurement failures almost always trace back to under-specification at the inquiry stage. Before approaching a furnace transformer manufacturer in India, your team should define:
1. Rated power (kVA or MVA): The transformer's power rating must account for the maximum continuous furnace demand plus a realistic overload margin. For arc furnaces, the rating is often expressed as the maximum kVA at the lowest secondary voltage tap.
2. Primary voltage: The incoming supply voltage — typically 11 kV, 33 kV, or 66 kV from the HT bus. This determines the primary winding design.
3. Secondary voltage range and tap steps: Furnace transformers require a wide secondary voltage range with multiple tap positions to control heat input precisely. Specify the minimum voltage (lowest tap), maximum voltage (highest tap), and the number of steps required.
4. Secondary current: The maximum short-circuit current the transformer must supply — a key driver of conductor sizing, bracing design, and impedance specification.
5. Impedance voltage (%): Determines short-circuit current limiting. Higher impedance reduces electrode current spikes but limits furnace power input. Typically 4–8% for arc furnace applications, but this varies by process.
6. Cooling type: Oil-natural-air-natural (ONAN), oil-forced-air-natural (OFAN), or forced oil and forced air (OFAF) cooling — determined by the size and duty cycle of the installation.
7. Duty cycle and on-time: Continuous vs. intermittent operation. Arc furnace transformers are typically rated for continuous duty at full load.
8. Special features: On-load tap changer (OLTC) for voltage adjustment under load, reactor for arc stability, buchholz relay, winding temperature thermometers, pressure relief, and oil level indicators.
Pro tip: Always specify the 'IEC 60076' standard as the design basis when sourcing furnace transformers in India. Also request that the manufacturer provide a thermal design calculation before order placement — this confirms that the proposed design can sustain the specified continuous load.
Why Sourcing from a Specialised Furnace Transformer Manufacturer Matters
General-purpose transformer manufacturers can produce standard distribution and power transformers efficiently. Furnace transformers are a different matter. They require:
Specific winding technology — flat-wound copper conductors, transposed cable conductors, or CTC (continuously transposed cable) for high-current secondary coils
Reinforced mechanical bracing — furnace transformers experience severe electromagnetic forces during arc ignition and short circuits
Special insulation systems — high humidity and elevated ambient temperatures in steel plant environments require enhanced insulation grades
Precise impedance matching — the transformer impedance must be matched to the furnace reactance to achieve optimal arc stability and power factor
Load cycle testing — type testing that simulates actual furnace operating conditions, not just standard routine tests
A manufacturer without dedicated experience in furnace transformer design risks producing equipment that fails prematurely, overheats under load, or cannot deliver the arc stability the process requires.
ETT as a Furnace Transformer Manufacturer in India
Electro-Tech Transmission Pvt. Ltd. (ETT), headquartered in Indore, Madhya Pradesh, manufactures furnace transformers for electric arc furnace, induction furnace, and submerged arc furnace applications across India's industrial belt. ETT's manufacturing facility includes:
Dedicated coil winding infrastructure for high-current furnace transformer secondary coils
In-house testing equipment including short-circuit test capability, temperature-rise testing, and impulse testing
BIS, BEE, ISO 9001:2015, and ISO 14001:2015 certifications ensuring quality and compliance
Engineering team capable of custom design to client specifications — including detailed thermal calculations and impedance matching
ETT has supplied furnace transformers to steel producers, foundries, and induction heating facilities across Madhya Pradesh and neighbouring states, building a track record in one of the most demanding application segments in the electrical industry.
How to Select and Qualify a Furnace Transformer Manufacturer in India: A Step-by-Step Guide
Define your technical requirements completely (see specification checklist above) before approaching suppliers.
Issue a detailed Request for Quotation (RFQ) that includes all operating parameters, standards compliance requirements, and testing expectations.
Evaluate technical proposals — not just price. Ask each supplier to provide a design basis document confirming their thermal, electrical, and mechanical design approach.
Verify certifications — check BIS, BEE, and ISO certificates for validity on official portals.
Request reference projects — specifically, furnace transformer installations at comparable capacity and application type.
Conduct a factory audit before order placement to verify winding technology, test infrastructure, and quality processes.
Agree on a factory acceptance test (FAT) protocol in the purchase order — this should include all routine tests per IEC 60076 plus any special tests relevant to your application.
Define warranty terms, spare parts availability, and on-site commissioning support before placing the order.
Frequently Asked Questions
Q: What is a furnace transformer and how does it differ from a standard power transformer?
A furnace transformer is specially designed to supply very high currents at low voltages to electric arc or induction furnaces. Unlike standard power transformers, furnace transformers must withstand extreme load fluctuations, short-circuit forces, and continuous high-load operation. They require custom-engineered windings, robust mechanical bracing, and a wide secondary voltage tap range — all features not typically found in standard distribution or power transformers.
Q: Which industries use furnace transformers?
Furnace transformers are used primarily in steelmaking (electric arc furnaces and ladle furnaces), foundries and casting (induction furnaces), ferro-alloy production (submerged arc furnaces), calcium carbide manufacturing, and induction heating lines for forging and heat treatment. Any industry that melts metal or requires high-temperature electrical heating is a potential user.
Q: What certifications should a furnace transformer manufacturer in India have?
At minimum: BIS certification as per relevant IS standards, ISO 9001:2015 for quality management, and testing in NABL-accredited laboratories. For furnace-specific applications, also verify that the manufacturer has experience with IEC 60076 type tests and can provide thermal design calculations.
Q: Can ETT manufacture furnace transformers for export?
ETT's furnace transformers are designed and tested to IEC and IS standards, making them suitable for both domestic and export applications. Contact ETT at [email protected] to discuss specific export requirements, documentation, and compliance needs.
Q: How long does it take to manufacture a custom furnace transformer?
Lead times for custom furnace transformers typically range from 8 to 16 weeks depending on the capacity, complexity, and material availability. ETT recommends early engagement at the project planning stage to ensure timely delivery aligned with your installation schedule.
Selecting the right furnace transformer manufacturer is a decision that will shape the reliability, efficiency, and safety of your furnace operations for the next 20–30 years. In India's rapidly growing industrial sector, the range of available manufacturers has expanded — but the quality gap between the best and the rest remains significant.
The key is to go beyond price and evaluate manufacturers on technical depth, certification credentials, factory capability, and sector-specific experience. ETT's combination of certified quality systems, custom engineering capability, and proven track record in furnace transformer supply makes it a credible partner for industrial procurement teams across India.
