Special Transformer Applications by Industry

A special transformer exists because a standard one cannot do the job. In practice that means one of four things: the current is too high for a normal secondary, the duty is too violent, the environment is too hostile, or the unit has to be built into equipment rather than into a room.

Steel and Electric Arc Furnaces

An arc furnace transformer supplies very high current at low voltage into an arc that is, electrically, close to a short circuit for part of every melt.

The duty is what makes it special. Load swings between the short circuit condition during scrap meltdown and a light load at the end of the heat, the current is unbalanced between phases, and the switching produces harmonic currents and voltage flicker on the supply. The transformer has to tolerate the mechanical forces of repeated near-fault events and the thermal cycling that goes with them.

Voltage regulation is normally on-load and over a wide range, because the arc voltage changes as the melt progresses and the operator needs to control power input without interrupting the process.

Electrochemical Industry and Rectifier Systems

Electrochemical plants consume DC, and they consume it in very large quantities at low voltage. The rectifier transformer sits between the AC supply and the rectifier, which makes it the first place the non-sinusoidal current appears.

Aluminium smelting potlines, where hundreds of kA flow through a series circuit.
Chlor-alkali electrolysis and hydrogen production.
Copper electrorefining and zinc electrowinning.
Other electrolytic processes requiring controlled DC at high current.

Two design consequences follow. The secondary is built from large cross-section copper arranged as multiple parallel paths, transposed to share current evenly and often water-cooled. And the harmonic current drawn by the rectifier produces eddy and stray losses that the thermal design has to include, which is why the rectifier topology belongs in the enquiry.

Metal Melting and Induction Heating

Induction furnaces and induction heating systems use a transformer to match the supply, sometimes as part of the power supply rather than as a separate unit. Frequencies above the mains mean the skin effect is stronger still, conductors are arranged and cooled accordingly, and the winding design departs further from ordinary practice.

Marine and Offshore

Ship and offshore installations add a set of constraints that have nothing to do with the electrical duty and everything to do with the environment.

Vibration and shock loading from machinery and from the sea state.
Salt spray and high humidity, which rule out open windings in most locations.
Restricted compartments, where fire safety and space are both tight.
Continuous operation with maintenance access that is difficult or impossible at sea.
Onboard distribution systems at 440 V or 690 V, with lower voltages downstream for lighting and small power.
Classification society requirements that apply to the installation as a whole.

Typical applications include main and emergency distribution, bow thrusters, propulsion supplies, HVAC, and deck machinery. Offshore, the same constraints apply on platforms and FPSO vessels, and offshore wind adds a substation transformer inside a constrained and largely unattended structure.

Renewable Energy

Solar and wind installations put the transformer where the generation is rather than where it would normally be sited. Inverter and battery stations are often compact enclosures, sometimes unattended, and the inverter output carries harmonic content that the transformer has to accommodate.

On wind turbines the transformer sits inside the nacelle or in the tower, which means dimensions, weight, and noise are all constrained, and vibration is continuous. Access for maintenance is by climb, so a design that needs regular attention is the wrong design.

Industrial Equipment and OEM Applications

The largest group covers transformers built into somebody else’s product or process. These units are usually designed around a machine rather than around a room, which changes the questions that matter.

Variable frequency drive systems and their input or output transformers.
DC motor drives and rectifier power supplies for older industrial equipment.
Welding power supplies and resistance welding.
Test equipment and laboratory supplies, where regulation and waveform matter more than efficiency.
Medical equipment and imaging systems.
Battery charging and energy storage interfaces.

For OEM work the arrangement is normally either built to print, where the customer supplies the drawing and we manufacture to it, or engineered to requirement, where the customer supplies the performance and we do the design. Both are routine, and which applies should be settled before the enquiry rather than during it.

What to Send Us

The application and the duty, not just the electrical rating.
Primary and secondary voltage, current, and the required regulation.
Environmental conditions: ambient, humidity, salt, dust, vibration.
Space, weight, and mounting constraints.
The applicable standard and any classification or certification requirement.
Whether the arrangement is built to print or engineered to requirement.

See the custom transformer range, the rectifier transformer range, the marine transformer range, or contact us with the details.

Related Applications

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