What Size Transformer for a 1‑Ton Induction Furnace Is Most Energy‑Efficient?

Transformer configuration must follow the core principle: power matching with a reasonable margin. The recommended standard solutions are as follows:

 

1. Capacity Matching 

For a 1‑ton induction furnace, the medium‑frequency power supply is typically rated between 600kW and 1000kW. The transformer capacity should include a safety margin. Recommended configurations:

• Standard configuration: 630kVA ~ 800kVA
• High‑efficiency configuration: 1000kVA (for high‑power supplies or "one‑to‑two" furnace arrangements)

 

Selection basis:

Transformer capacity is generally 1.2 times (for series inverters) to 1.4 times (for parallel inverters) the medium‑frequency power supply rating. This margin accommodates harmonics, inrush currents, and system losses.

 

2. Voltage and Winding Configuration

Input voltage: 10kV, 35kV (typical)

Output voltage: 400V, 575V, 660V, etc. (exact value must be confirmed with the furnace manufacturer)

Preferred structural type: 12‑pulse rectifier transformer

Adopts dual windings (Y/Δ connection) – effectively eliminates 5th and 7th harmonics, reduces grid interference, and meets environmental requirements.

 

3. Model and Material

Recommended series: S11 or S13 (oil‑immersed type)

Insulation class: F or H class recommended – withstands intermittent heavy load impacts typical of induction furnace duty cycles.

 

4. Important Considerations

• Harmonic mitigation: An induction furnace is a classic harmonic source. If a 12‑pulse design is not used, install a reactive power compensation device (such as an SVG) upstream of the transformer to improve the power factor.
• Cooling distance: Keep the distance between the transformer and the medium‑frequency power supply cabinet within 10 meters to minimise cable voltage drop.

 

Summary:

For a 1‑ton furnace, the most economical configuration is a 630kVA transformer, delivering a melting cycle time of approximately 50 minutes.

 

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Technical Specifications – 630kVA Induction Furnace Transformer 

Parameter	Recommended Value
Rated power	630 kVA
Primary voltage	10 kV / 35 kV
Secondary voltage	400V, 575V, 660V (custom, per furnace)
Frequency	50 Hz / 60 Hz
Vector group	Dyn11 or Yd11 (for 12‑pulse configuration)
Cooling method	ONAN (oil‑natural air‑natural)
Impedance voltage	5.5% – 6.0%
No‑load loss	≤ 910 W (for S13 series, Tier 2)
Load loss (@ 120°C)	≤ 8,100 W
Insulation class	F (155°C) or H (180°C)
Winding material	100% copper (recommended for heavy duty)
Core material	CRGO silicon steel (step‑lap)
Applicable standards	IEC 60076, GB/T 6451, CSA, CE

 

How Much Can You Save with the Right 630kVA Unit?

Many furnace operators overlook transformer losses. A standard S9 or S11 630kVA transformer may have no‑load losses of 1200‑1500W and load losses above 10,000W.

 

Upgrading to an S13 (or S15) high‑efficiency 630kVA transformer cuts:

• No‑load loss by 25‑35%
• Load loss by 15‑20%

 

For a 1‑ton furnace running 300 days a year, 10 hours per day, the annual energy saving often exceeds 8,000‑12,000 kWh. At 0.12/kWh,that's0.12/kWh,that's1,000‑1,500 saved every year – directly reducing melting cost per ton.

 

When Should You Choose 800kVA or 1000kVA Instead?

While 630kVA works for most single‑furnace, one‑shift operation, consider a larger unit if:

• Your 1‑ton furnace is rated >700kW power supply
• You run two furnaces alternately on one power supply ("one‑to‑two")
• Ambient temperature regularly exceeds 40°C
• You plan to add a second furnace in the future

In those cases, step up to 800kVA (moderate margin) or 1000kVA (conservative margin). But for the majority of standalone 1‑ton furnaces, 630kVA remains the most cost‑effective and energy‑efficient choice.

 

Conclusion: Optimise Your 1‑Ton Furnace with a 630kVA Transformer

Choosing the right transformer directly affects your melting cost, production uptime, and equipment lifespan. For most 1‑ton induction furnace applications, the 630kVA transformer – preferably a 12‑pulse S13 oil‑immersed unit with F/H insulation – gives you the best balance of first cost, energy efficiency, and harmonic performance.

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Looking for a reliable 630kVA transformer for your induction furnace?

We are Henan GNEE Electric Co., Ltd., a factory‑direct supplier with IEC/CE/UL certifications. We supply 630kVA oil‑immersed transformers, 12‑pulse rectifier units, and complete MV/LV substations to furnace manufacturers and end‑users worldwide. Request your customised quote today – tell us your furnace rating and secondary voltage, and we'll propose the most economical, energy‑saving solution within 24 hours.