Insulation is one of the most important qualities that a transformer has, which is responsible for providing better performance when the transformer is operated. In fact, the durability and stability of a transformer highly depend upon the proper utilization of the insulation materials present within it. This means that other than metallic components like silicon steel and copper, there are also other important insulating materials used in power transformers for better functioning. You must get in touch with a reliable transformer manufacturer in India like Miracle Electronics so that you can rest assured that the transformers you buy will be of top-class quality with the best materials, both metallic and insulating, installed within. Now, let us take a look at the list of insulating materials present in a transformer, along with their uses and applications.
Insulating oil is one of the most important components within a transformer that acts as both an electrical insulator and coolant to dissipate heat losses. This oil is seen in 11kV or higher voltage transformers, placed in the tank where the transformer core is placed. It is not required in low voltage transformers as the heat dissipation in such transformers is very low. Insulating oil is obtained by fractional distillation and subsequent treatment of crude petroleum.
Insulating paper is made up of vegetable fibers that are felted together to form a sheet. The fibers are obtained from plants like cotton, straw, hemp, manila, and coniferous trees. When this insulating paper is put into the insulating oil under vacuum, it attains extremely high electric strength.
As the name itself says, insulating tape is used for various taping purposes. These are available in a variety of forms like cotton tapes, woven tapes, glass woven tapes, and phenol laminated paper base sheet. These tapes are used in areas where high strength is required. They are also used for banding of transformer cores.
Used in the electrical, mechanical, and thermal designing of transformers, the pressboard is also made up of vegetable fibers that contain huge amounts of cellulose. These pressboards can be moulded into any shape to be used in transformers; the most commonly seen shapes being angle rings and caps.
Wood-based laminates are made from selected veneers that are obtained from various timbers. The veneers are first dried, and then are partially/completely saturated naturally. Such laminates are used in areas that require higher mechanical and lower electric strength. They are used in making a variety of components like coil clamping rings, cores, yokes, and supports.
All these insulation materials used in transformers are based on their temperature withstanding capacity. They are classified into classes A, B, C, E, F, H, and Y. Let us understand all these classes in detail.
- Class A materials are those whose maximum hot spot temperature is 105°C. These include cotton, silk, and paper for impregnation.
- Class B materials are those whose maximum hot spot temperature is 130°C. These include glass fiber, mica, and asbestos with suitable impregnation or coating substance.
- Class C materials are those whose maximum hot spot temperature is 180°C. These include glass, mica, asbestos, porcelain, and quartz with or without an inorganic binder.
- Class E materials are those whose maximum hot spot temperature is 120°C. These include wire and enamel.
- Class F materials are those whose maximum hot spot temperature is 155°C. These include glass, mica, and asbestos with suitable binding impregnation or coating substances.
- Class H materials are those whose maximum hot spot temperature is 180°C. These are a combination of materials like glass fiber, asbestos, and mica suitable bonded together.
- Class Y materials are those whose maximum hot spot temperature is 90°C. These include cotton, silk, paper, and wood without impregnation.