What is insulation system?

An insulation system is a tight combination of two or more insulating materials used for electrical equipment. After extensive testing, it is proven that these insulating materials combined together can withstand long-term conditions that do not exceed the level of the insulation system. At a limited temperature, there will be no significant weakening of the insulation performance.

Winding wires,ground and interwinding insulations,tapes,spacers&wedges,varnishes all should be defined under a insulation system.

At present,Eugenia Tech work with UL and IEC as insulation system reference.


What are transformer insulators?

Insulation material is one of the most important materials in transformers. Its performance and quality directly affect the reliability of transformer operation and the service life of transformer. In recent years, new insulation materials used in transformer products have emerged one after another. With the rapid development of science and technology, electrical equipment such as motors and transformers are increasingly used. The reliability and service life of a transformer depend largely on the insulating materials used.

Insulating materials can be used to isolate conductors that are charged or at different potentials and allow current to flow in a certain direction. In transformer products, insulating materials also play the roles of heat dissipation, cooling, support, fixation, arc extinguishing, improving potential gradient, moisture-proof, mildew-proof and protecting conductors. Insulation materials are classified according to voltage levels: generally divided into: Y (90℃), A (105), E (120℃), B (130℃), F (155℃), H (180℃), C (greater than 180℃) ℃). The heat resistance grade of the transformer insulation material refers to the maximum temperature that the insulation material is allowed to withstand in the transformer. If the insulation material is used correctly, the service life of the material can be guaranteed for 20 years. Otherwise, it will be reduced according to the 8℃ law (for every 8℃ increase in the temperature of Class A insulation, the service life is reduced by half, Class B insulation is 10℃, and Class H is 12℃. This law is called the 8℃ law of thermal aging) service life.

There are many types of transformer insulation materials, which can generally be divided into gas insulation materials, liquid insulation materials and solid insulation materials according to their forms.

Solid insulating material: The solid insulating material used in transformers refers to insulating materials that are solid in form or become solid after chemical reactions or physical changes. There are many types of solid insulation materials for transformers, such as insulating paper, insulating cardboard, Nomex paper, adhesive paper, electrical laminated wood, epoxy glass cloth board, low dielectric loss laminate, insulating paint, insulating glue, cotton tape, compression tape, Mesh weftless polyester tape, etc.

Insulating Paper

The insulating paper mentioned here refers to pure sulfate wood pulp paper. Other insulating papers include synthetic fiber paper (such as NOMEX paper), nitrile insulating paper (such as Denison paper), etc.

Insulating Crepe Paper

It is made of electrical insulation paper through wrinkle processing. There are wrinkles along its transverse direction, and the wrinkles are pulled apart when stretched. The thickness of insulating paper is generally 0.05mm~0.12mm, and the elongation range is 5%~200%. 

Dennison Paper

During the manufacturing process, bisnitrile amine, vinyl cyanide, etc. are added to the pulp. Produced by Dennison Company of the United States, the paper is characterized by being wrinkled and calendered, with good mechanical cyanide and appropriate elongation. It is an ideal material for the insulation of large transformer winding turns. Using it to wrap transposition wires can ensure Pack tightly without swelling.

Nomex Paper

It is a heat-resistant synthetic fiber paper produced by DuPont in the United States. Nomex is the trade name for this fiber paper. The main component of Nomex is aromatic polyamide, which has good heat aging properties. It can be used for a long time at 220℃ and is a Class C insulation material.

Diamond Paper

The insulating paper has a diamond-like pattern and is used for interlayer insulation of transformers. It does not need to be directly dried after being treated with Fanli water. The coils can be closely adhered to increase the mechanical strength of the coils.Its heat resistance grade is Grade A 105℃,can be used in high voltage oil-immersed transformer.

Metalized Paper

Used for grounding shielding and electrostatic shielding. The bottom paper is 0.2mm thick insulating paper, and the aluminum foil thickness is 0.02mm for the insulation wrapping of the lead wire and insulation shield.

Insulating Cardboard

Made from paper made from kraft wood pulp. It is used for oil gap spacers, partitions, cardboard tubes, corrugated paper, iron yoke insulation, clamp insulation and end insulation winding pressure plates of cake windings.

Insulating Tube

The insulating tubes used in transformers include phenolic tape tubes, epoxy glass cloth tubes, fiberglass tubes and cardboard tubes.

Corrugated cardboard

In the oil plate gap structure composed of multi-layer paper tubes in high-voltage transformers, corrugated cardboard can be used instead of stays to form the oil gap. This insulation structure can save insulation materials while ensuring insulation performance.

Electrical Laminates

An insulating material with a layered structure made of paper, cloth and wooden veneer as the base material, dip-coated with different adhesives, and hot pressed or rolled.

Nomex Pressboard

A cardboard made of synthetic material based on aramid fiber.

Epoxy Galss Fiber Rod

The interstage rods, air gap stays, screws and screws of dry-type transformer core columns often use epoxy  glass fiber rods.

Electrical Films& Electrical Composite Materials

They have excellent dielectric properties and are all thin insulating materials. Electrical films include polypropylene film, polyester film and polyimide film. Composite materials are composite products made of fiber materials bonded to one or both sides of the film.

Glass Linoleum

Glass varnish cloth is made from alkali-free glass cloth used by electricians, soaked in insulating paint and baked. For use in dry-type transformers.

Binding Material

Insulating materials used for transformer binding include cotton tape, compression tape, semi-dry thin wire tape, mesh semi-dry tape without weft, glass cloth tape and polyester rope, etc.