One Transformer per Induction Furnace or One for Two Furnaces?
Should a project use one transformer per induction furnace, or can one transformer feed two furnaces? The answer depends on the converter arrangement, whether the furnaces run together, the duty cycle and the required production flexibility.
Furnace tonnage alone cannot answer it. The transformer must match the rectifier, inverter, switching, protection and cooling.
Why one transformer per induction furnace is often selected
With a dedicated arrangement, one transformer normally feeds one converter and one furnace line. The voltage, current, pulse number and duty can be matched to that converter. Protection and interlocking are also easier to define for one load path.
Separate units may allow one furnace line to stop while the other remains available. This depends on the upstream switchgear and must be confirmed in the single-line diagram. Two units also need more space, cables and investment.
When can two furnaces share one transformer?
Sharing may be possible when the converter manufacturer has designed the system for it. Some plants have one power supply that switches between two furnace bodies. In that arrangement, the operating sequence and electrical interlock prevent both furnaces from demanding full melting power at the same time.
Another system may have two converters that can run together. The transformer must then be rated for the confirmed simultaneous load and harmonic duty. It also needs a secondary winding and terminal arrangement that matches both rectifier circuits.
Buyers should not connect a second furnace to an existing transformer only because unused kVA appears to be available. The existing winding current, impedance, cooling, protection and short-circuit strength must all be reviewed.
Three layouts that buyers should not confuse
The first layout is one transformer, one converter and one furnace. The power path is direct.
The second uses two transformers and two converters. The upstream system must still have enough capacity for both lines.
The third uses one power supply that switches between two furnace bodies. It is not the same as running both at full power. The converter supplier must define the sequence and interlocks.
Real project: two transformers for two 15-ton furnaces in Russia
XINGNIU received a repeat order from a Russian smelting plant. The confirmed project arrangement included two transformers for two 15-ton medium-frequency induction furnaces. The transformers used a 24-pulse design.
This case confirms the equipment quantity, furnace tonnage, country, repeat purchase and pulse configuration. It does not confirm the rated kVA, primary voltage, secondary voltage, impedance, cooling method, losses or temperature rise. Those values should not be published until the approved drawing, nameplate or test report is checked.
The case also should not be used to claim that every 15-ton furnace needs the same transformer. Melting time, metal type, converter power and production schedule can change the required electrical design.
What the 24-pulse design changes
A 24-pulse rectifier system needs coordinated secondary winding groups and phase relationships. The transformer connection must follow the converter drawing. Pulse number by itself does not define the rated capacity or decide how many furnaces one transformer can supply.
The buyer should provide the rectifier topology, number of bridges, required secondary voltages and currents, phase-shift requirements and terminal arrangement. These items must be agreed before manufacturing.
Simultaneous operation changes the transformer duty
For two furnace lines, state whether both will melt at the same time. Also state whether one furnace melts while the other holds temperature, or whether only one line operates at a time. These modes produce different loading patterns.
The factory also needs the converter input power, power factor, overload curve and expected cycle time. Without this information, the designer cannot confirm capacity, thermal duty or cooling.
Protection, maintenance and shutdown planning
Each furnace line needs a clear isolation and protection plan. The project should define upstream breakers, transformer protection, converter protection, emergency trips and cooling-failure interlocks.
A shared transformer may create one common shutdown point. Separate units reduce that dependency only when the bus and switchgear allow safe independent isolation.
Loss, temperature rise and impedance
The technical offer should state the agreed no-load loss, load loss, temperature-rise limits and impedance. These values affect operating cost, heating, voltage drop and fault current.
XINGNIU uses full-capacity design and focuses on low loss and low temperature rise. The guaranteed values must be project-specific and recorded in the approved technical sheet and factory test report.
Information needed for a quotation
Send the number of furnaces, furnace tonnage, metal type, target melting time, converter make and model, input power, primary voltage, secondary voltage, pulse number and rectifier diagram. Also state whether the furnaces operate together, alternate, or use one line as backup.
Add the load cycle, overload requirement, site temperature, altitude, cooling preference, required impedance, protection and available installation space. For a replacement project, include the old nameplate, drawings and test report.
XINGNIU supply and delivery
XINGNIU is a direct transformer factory. We customize furnace transformers to the converter, voltage, pulse arrangement, load cycle and site conditions.
After the technical details are confirmed, normal production takes 15 to 25 days. The warranty is one year.
FAQ
Can one transformer supply two induction furnaces?
It can in some engineered systems. The converter arrangement, simultaneous load, switching, interlocks, windings, protection and cooling must all be designed for that operating mode.
Does a 15-ton furnace determine transformer kVA?
No. Furnace tonnage is only one input. Converter power, target melting time, metal type, duty cycle, efficiency, power factor and overload requirements are also needed.
Is 24-pulse required for every large furnace?
No. Pulse number should follow the converter design, grid conditions and harmonic requirements. It is not selected from furnace tonnage alone.
If you are deciding whether to use one transformer per induction furnace, send XINGNIU the converter data, furnace operating plan and single-line diagram. Our engineers will review the load arrangement before preparing the technical proposal and quotation.
