Electric Furnace Transformer | Three Phase Oil Cooled Furnace Transformer Manufacturer

Product Overview

We build this Electric Furnace Transformer as a three-phase, oil-immersed unit for plants that melt metal or mineral charge on a heavy, continuous schedule. It is not a catalogue item: capacity, voltage ratio, tap arrangement, impedance and connection group are all worked out around the furnace it will feed, so the unit matches the melting load rather than the other way round. As a furnace transformer manufacturer we start from the supply you already have on site and design the secondary current and voltage your electrodes or melting bath genuinely need.

In the plant, the transformer sits between the incoming supply and the furnace. It steps the supply down to melting voltage and then holds that output while the load moves through a heat. That is the part of the job that separates a furnace transformer from an ordinary distribution unit: melting loads surge, stall and recover within seconds, and the secondary voltage has to stay usable through all of it.

You usually come to us in one of three situations. An EPC or design team is specifying the electrical package for a new melting line. A smelting plant is replacing a unit that has failed or been outgrown. Or a maintenance and purchasing team needs a unit for a line that is already running and cannot afford to stop. All three need the same thing first: a rating that genuinely matches the duty, not one that merely looks close on paper.

Where a furnace runs on direct current, the supply passes through a Rectifier Transformer before it reaches the electrodes. We build both sides of that chain, so the two units can be matched on ratio, impedance and tap range in a single design review rather than reconciled afterwards by two different suppliers.

Key Features

• Stable output through the melting cycle: tap adjustment follows the load, so the voltage the furnace sees stays close to what the process needs as the charge melts, refines and slags.
• Built around your furnace: capacity, voltage ratio and connection group come from your duty rather than a fixed list, which means a custom furnace transformer instead of a compromise.
• Cooling matched to the schedule: oil-immersed construction with the cooling arrangement chosen for how hard and how long the unit runs.
• Low noise, low loss operation: less energy lost as heat over years of service, and a quieter transformer bay than the process around it.
• Made for impact loads: windings and their clamping are built to ride through the surge and short-circuit events that come with electrode operation.
• Built for long campaigns: specified for extended high-temperature running rather than intermittent bursts.

Specifications

Tank, Cooling & Build

The tank is welded from thick carbon steel plate and finished in light grey anti-corrosion paint. That finish is doing real work in a melting shop, where damp, dust, heat and process fumes attack bare steel quickly. The heavier the plate, the better the tank also absorbs the vibration that travels through a furnace building.

Inside, the core and windings sit in insulating oil, which cools them and insulates them at the same time. Corrugated radiator banks welded to the tank wall give that oil a large surface area to lose heat through. In the standard ONAN arrangement the oil circulates naturally and heat leaves through the radiators; where the unit runs close to its rating for long stretches, ONAF cooling adds fans that push more air across the same radiator surface.

A conservator sits above the tank so the oil has room to expand and contract with load and ambient temperature, and so the oil level stays visible on a routine walk-round. The temperature indicator, pressure relief valve and control box are grouped together, which means readings and protection devices can be checked from one position instead of three. Bushing terminals on top carry the secondary current out to the furnace circuit, and the flat base frame lets the whole unit be set down on the prepared foundation as a single block.

Every choice in this construction answers to the duty. Melting furnaces do not hold a steady load, they surge, stall and recover, so a heavy tank, generous radiator area and a conservator with real oil volume are what let the transformer absorb that pattern for years rather than seasons.

Applications in Melting Plants

• Steelmaking melting and refining lines: an arc furnace pulls hard and unevenly as the charge melts, refines and slags. A low-impedance secondary with high current capability keeps the arc stable, and tap adjustment tracks the load so the voltage does not sag with it. Used as a steelmaking electric furnace transformer, the unit keeps working through the heat, dust and vibration of a melt shop instead of being nursed through every shift.
• Rock wool melting furnaces: rock wool lines run long and hot with a load that rarely settles. Power has to be matched to the melting furnace's own voltage and capacity, and the supply has to hold through extended high-temperature campaigns. Short-circuit withstand and continuous overload capability matter most here, and a compact structure fits into the furnace's electrical network without a rebuild.
• Ferroalloy and ore smelting: submerged arc furnaces draw sustained high current and take frequent impact loads as the charge shifts. The winding design keeps arc conditions steady and trims power loss during smelting, while the sealed, painted tank stands up to the dust and heat of the workshop. Connected to the furnace control system, it helps hold smelting parameters steady and cuts unplanned downtime.
• DC-powered melting lines: where a furnace runs on direct current, the AC supply is converted through a Rectifier Transformer before it reaches the electrodes. We build both units together, so turns ratio, impedance and tap range are settled in one design review rather than reconciled afterwards.

Selecting the Right Configuration

1. Start with the furnace, not the transformer. Melting rate, charge material and the shape of the load over a heat tell us the capacity the unit has to carry, and they usually point somewhere different from a simple nameplate comparison.
2. Fix the voltage ratio. The primary voltage available on site and the secondary range your electrode control or melting bath needs are the two numbers the build hangs on; everything else follows from them.
3. Decide how many tap steps your operators need. A wider tap range lets one unit cover melting, holding and a future change in charge mix without ordering again.
4. Match cooling to the schedule. Where a unit has time to shed heat between heats, natural oil circulation is enough; where it runs near its rating for long stretches, fan-assisted cooling earns its place.
5. Settle connection and impedance with the furnace builder. Their drawings set the connection group and the impedance band the melting process was designed around, and a furnace transformer has to sit inside that band.
6. If you are replacing a unit, tell us how long it has run and whether the duty has changed since it was installed. Both affect what the new custom furnace transformer should be rated at.
7. Describe the installation: indoor or outdoor, ambient heat and dust, and the space available in the transformer bay. These conditions shape how the unit itself is arranged.

Nameplate Data

Ordering, Delivery & Commissioning

1. Send your duty data, and if you are replacing a unit, a photograph of its nameplate or the original drawings. Our engineers confirm the rating and the design points that follow from it, and quote against that confirmed specification.
2. Approve the design before production. Because we are a furnace transformer manufacturer working in our own plant rather than through traders, your questions go to the engineers who will wind and test the unit, and winding, tap and cooling details are fixed in writing before the tank is built.
3. Factory testing. Every unit passes its full routine tests in our own test laboratory before dispatch, and the test record travels with the transformer.
4. Packing for sea freight. The transformer is cleaned and inspected before shipment, fixed to a steel base frame, wrapped in waterproof plastic film and cased in wood. That packing is specified for container loading, and spare parts travel separately so nothing heavy rests on them across a long ocean transit.
5. Transport planning. This is a heavy, awkward load, so route, crane capacity and the offloading point are worth settling early. Our team supports the delivery arrangements and shares the transport information your contractor will ask for.
6. Installation and commissioning. The unit is set on the prepared foundation on its base frame, the bushing and control cabinet connections are made, and commissioning follows the supplied documentation. Our engineers guide the sequence remotely and travel to site where the project calls for it.
7. Warranty and after-sales. Standard cover runs 12 months from equipment commissioning or 18 months from factory delivery. Long-term technical support and spare parts supply continue after that, and your maintenance team can reach us for troubleshooting during the unit's service life.
8. Commercial details. Lead time depends on the capacity and how far the design moves from standard, so confirm the current schedule, payment terms and shipping arrangement with your sales contact.

Maintenance & Care

• Oil level and oil temperature are the two readings worth watching on every round. Check the conservator level, read the temperature indicator, and compare both against what the same load produced when the unit was new — a slow upward drift under steady load is the earliest sign that heat is not leaving the tank the way it should.
• Keep the radiator faces clear. Corrugated radiator banks lose much of their cooling capacity once dust and process fume coat the fins, so brush or blow them down on a schedule that suits your shop rather than waiting for the oil temperature to tell you.
• Where the unit runs with ONAF cooling, the fans are the moving part. Confirm they cut in with load, that airflow across the radiators is unobstructed, and that the control box stays free of dust and moisture.
• Look over the bushing terminals and connections on top at each inspection. Dust build-up, tracking marks, and terminals that have discoloured or worked loose are the usual findings, and they are quick to correct before they turn into a fault.
• Sample the oil if your maintenance regime includes it. Dielectric strength and moisture content say more about the state of the winding insulation than any gauge on the tank, and the documentation supplied with the unit sets the intervals to follow. Never top up with an oil type that has not been confirmed against the oil already in the tank.
• Work the tap changer through its positions periodically so the contacts do not sit in one place for years, and check the indicated position against the tap table whenever the furnace duty changes.
• Watch the seals and joints — gaskets, the conservator, radiator flanges and the drain valve seats below the tank. A weep caught early stays a weep; one left through a long wet season does not.
• If the unit stands outdoors before energisation, keep it on its base frame on firm ground with the bushings and radiator faces clean and dry, and check the oil level again before first energisation rather than after.
• The most common mistake is treating a furnace transformer as fit-and-forget. Running with blocked radiators, ignoring a rising oil temperature, or energising a unit that has stood for months without checking oil level and bushings are the failures that shorten service life. Routine attention on this oil immersed furnace transformer does not involve lifting the core or opening the tank.
• Spare parts supply continues for the life of the unit. Tell us at order stage which items you want held alongside the transformer, and they are packed separately so nothing heavy rests on them during transit.

Technical Support & Model Matching

Every project starts with our engineering team. Share your duty conditions, drawings or existing nameplate data, and we help confirm the right rating and configuration before production begins — selection assistance, model matching, and troubleshooting before and after delivery. Backed by more than fifty years in transformer manufacturing, our engineers travel to site for installation and commissioning guidance and stay reachable remotely once the unit is energised. Functions and parameters can be customised to your project, and our quality system holds ISO9001 with IEC, CSA and CTQC testing.

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