Catalogue

Transformers for power supply of electric arc steel-melting furnaces (EAF) are available for furnaces of "small" capacity from 0.5 to 12 tons and furnaces of "large" capacity from 25 to 200 tons. Transformers for furnaces  of "small" capacity  are installed in foundry or other smelter machine-building enterprises and have primary voltage 6 or 10 kV; identical design of the magnetic system and windings; one kind of voltage regulation (NLTC) by tap changing in the HV winding; built-in current-limiting reactors to protect against operating   short-circuit; different types of cooling.

Transformers for furnaces of "big" capacity equip main arc-furnace shops of metallurgical plants. They are executed for   primary voltages from 10 to 220 kV; they have LV control scheme  only on load (OLTC),sometimes with the help of  separate regulating transformers and cooling system with forced circulation of water and oil (type C).

According to the purpose and scope of application, converter transformers are divided into transformers for: DC electric drives, exciters of synchronous generators, rectifiers and inverters of electrified railways, DC arc furnaces, electro thermal installations, electric drives of drilling rigs, frequency converters, cell plants, electrographic furnaces, electrochemical Installations.

Converter transformers are manufactured in the following versions: two and triple-wound, 6-, 12- and 24-phase bridge rectification circuits, with split windings and without splitting, with OLTC or NLTC with different depth of regulation, and also with an equalizing reactor. Rated power of oil converter transformers, at present, varies from 1 to 110 MVA with the supply voltage of 6, 10, 35, 110 kV.

Ore-smelting electric furnaces have the widest range among electrometallurgical units due to a large variety of brands of manufactured commercial products and implemented technologies (only electric resistance furnaces have a wider nomenclature). Regenerative processes in the furnaces require low secondary voltages and high currents.

In addition, depending on the smelted material, it is necessary to change the operating regime of the furnace, i. e., to regulate voltage and amperage in wide ranges. The company "Delta Trafo" produces a wide range of transformers for ore-smelting furnaces for different purposes: single-phase and three-phase,   primary voltages 6-220 kV, with NLTC or OLTC voltage regulation and power range from 500 kVA to 100 mVA.

Due to the fact that induction channel, crucible furnaces and mixers of different capabilities and   capacities are widespread, it was required to create a new series of special electric-furnace transformers. Induction furnaces are used for smelting of ferrous and nonferrous metals and their alloys, for metal overheating before casting and alignment of its chemical composition, doping, as well as for maintaining   constant temperature during molding.

The main feature of transformers for electric induction furnaces is great depth of the secondary voltage control (D> 6). Another feature is the need for constant power at several stages of LV which increases standard capability and mass of an EFT.

Electroslag remelting furnaces are aggregates of secondary remelting for the production of metals and alloys of high quality. Electroslag remelting (ESR) is the purification of metal from sulfur, nonmetallic inclusions and gases. Metal ingots, obtained by the ESR method, differ from conventional one by dense and homogeneous macrostructure, absence of shrinkage cavities and porosities. The outer surface of the ingots is smooth; it does not require peeling-off or stripping before hot machining.

The main requirement for transformers of this type is providing small stage regulation of secondary voltage at the regulation depth of 2.5-4.