Insulation materials for dry type transformers

Dry type transformer is one of the most important equipment in power system. The choice of insulating material and application is directly related to the performance, safety and service life of the transformer.

Dry type transformer

Insulation materials for dry type transformers

Fiberglass laminated sheets

Fiberglass laminated sheets‌ is a kind of sheet the is made of glass fiber cloth and epoxy resin and other materials. It has many characteristics such as sound absorption, sound insulation, heat insulation, environmental protection, flame retardant and so on. It is usually used in the manufacture of circuit boards, insulating pads, transformer insulating parts, etc. It is widely used in the manufacture of electronic and electrical equipment‌.

Prepreg DMD

Prepreg DMD‌ is a material made of polyester film and polyester nonwoven soft composite impregnated with heat-resistant modified epoxy resin and baked. This material has excellent electrical properties, heat resistance, flame retardant and long storage life at room temperature. Prepreg DMD is widely used in interlayer insulation of low voltage coils of dry type transformers, slot insulation and phase insulation of class F motors, and slot insulation and turn insulation of class B and F motors‌.

SMC sheets

SMC sheet is molded from unsaturated polyester glass fiber reinforced laminate molded products in various colors. It has good insulation, high mechanical strength, flame retardant, leakage resistance, arc resistance, dielectric strength and high voltage resistance characteristics. In the dry type transformer, SMC sheet is mainly used to make insulating parts, such as insulation partition, insulation support, arc extinguishing cover. ‌‌

NHN insulation paper

NHN insulation paper ‌is a soft composite material composed of a polyimide film in the middle and Nomex (American DuPont paper) on both sides, which has excellent heat resistance and good mechanical properties. Its heat resistance grade is H (180℃). It is suitable for groove, groove cover and phase insulation of high heat resistance motor. It can also be used as layer insulation of transformer or other electrical appliances. ‌‌

PET film

PET film‌, called Polyethylene Terephthalate Film, is a kind of high-performance plastic film. It is derived from the fine processing of polyethylene terephthalate (PET), a high-performance polymer. It is made ‌by advanced extrusion technology and bidirectional drawing process. PET film has good dielectric and mechanical properties. It is mainly used for insulation between high and low voltage coils of dry type transformers. And it can also be used for interturn insulation and liner insulation in motors and electrical appliances‌.

PI film

PI film, or polyimide film, is a high-performance film material with excellent mechanical properties, electrical properties and heat resistance. In dry type transformers, PI film is mainly used as insulation material for high voltage windings. Due to its excellent high temperature resistance and mechanical strength, PI film can withstand the high temperature environment in the working process of the transformer to ensure the stability of electrical insulation‌. In addition, because of its good insulation properties and heat resistance‌, PI film is also commonly used in low-voltage winding of dry type transformers.

There are a wide variety of insulation materials in dry type transformers, and each material has its unique properties and scope of application. When selecting insulation materials, it is necessary to consider factors such as insulation strength, high temperature resistance, weather resistance, mechanical strength and fire resistance. Through reasonable selection and application of insulation materials, the performance, safety and service life of dry type transformers can be ensured. At the same time, with the continuous progress of science and technology and the continuous emergence of new insulation materials, the insulation technology of dry type transformer will also be continuously developed and improved.