The materials used in box-type transformers are primarily selected based on electrical performance, mechanical strength, insulation performance, and environmental adaptability. They can generally be categorized into four main types: enclosure materials, transformer core materials, electrical conductor materials, and insulation materials.
Enclosure Materials: These are typically made of cold-rolled steel sheet or stainless steel sheet. Cold-rolled steel sheet, after anti-corrosion treatment (such as powder coating or galvanizing), offers good strength and cost advantages. Stainless steel is often used in coastal, high-humidity, or highly corrosive environments, offering superior rust and corrosion resistance. The enclosure exterior is also coated with UV-resistant and anti-corrosion coatings to withstand long-term outdoor operation.
Transformer Core Materials: Similar to ordinary transformers, the core is generally made of laminated cold-rolled grain-oriented silicon steel sheets to reduce hysteresis and eddy current losses. The windings commonly use high-purity electrolytic copper or aluminum conductors. Copper conductors offer better conductivity and are suitable for large-capacity and critical applications, while aluminum conductors are used in cost-sensitive or small-to-medium capacity equipment.
Insulation and Auxiliary Materials: Oil-immersed prefabricated substations typically use mineral insulating oil or natural ester oil, combined with insulating paper, insulating boards, and other materials to form an oil-paper insulation system. Dry-type prefabricated substations mostly use epoxy resin casting or Nomex high-temperature resistant insulation materials, which have fire-resistant and moisture-proof properties. Cable joints, busbars, and supporting structures commonly use copper busbars, aluminum busbars, and high-strength engineering plastics or composite insulation materials to improve safety and durability.
