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Selection of Insulation And Thermal Class for Dry-Type Transformers

May. 27, 2021


Dry-type transformers work in the same way as other transformers, following the physical principle of using the voltage technology required to couple electricity and magnetism: when current flows through a wire current, it generates a changing magnetic field or "magnetic" surrounding environment. The wire fluctuates around the magnetic field and the current it generates in the wire. Thus, in the second and first wires, there will be fluctuating magnetic fields and the current will be induced to flow in the second wire. And the electricity is carried through two conductors that are not actually in contact with each other. Next, the dry-type transformer supplier will share them with you.


Firstly, dry-type transformers have the advantage that they are oil-free and bulky, reducing the risk of fire. It reduces the investment spent on fire prevention; saving corresponding investments in disaster prevention and civil engineering. In addition, the absence of oil leaks in dry-type transformers reduces the maintenance work involved in the daily operation of the transformer and eliminates the need to change the oil if it does not need to be regularly tested for aging. This significantly reduces daily maintenance costs.

Selection of insulation and thermal class for dry-type transformers

The insulation and heat resistance of dry-type transformers is getting higher and higher. At present, Class F products are largely popular and Class H products have also been produced. As a technical indicator, this is technological progress. However, in the practical application of the project, the combined conditions of use and the surrounding environment must be taken into account.

Resin Dry-Type Transformer

Resin Dry-Type Transformer

When elected the class H transformer, whether the equipment connected to it and other equipment in the same room can also When elected the class H transformer, whether the equipment connected to it and other equipment in the same room can also withstand the temperature of class H insulation. For example, whether to choose class H insulated cables, etc. If the equipment in question does not meet the requirements of class H, the equipment will not be allowed to reach class H temperatures during operation and therefore class H insulation is meaningless. This is especially true when the transformer is arranged in the same room as other equipment, even though the transformer can reach a heat-resistant temperature of 180°C.


However, when the transformer's operating temperature actually reaches 180°C, the ambient temperature already far exceeds the permissible temperature of the distribution equipment. Particularly in the case of products with thermal protection elements, the electronic components will not work properly due to the ambient temperature, resulting in abnormal protection, as the products work by detecting temperature changes at room temperature when the room temperature exceeds room temperature. 

For this reason, electrical components in distribution cabinets are never allowed to reach an ambient temperature of 180°C. If for this purpose it is not possible to arrange transformers and distribution cabinets in the same room and to install class H insulated transformers in a separate transformer room.


As a rule, only the transformer can achieve class H insulation, while other associated equipment cannot, and even if only class H insulation is achieved, the transformer will not function to its full potential, which is effectively a waste. . In this respect, in practical engineering, whichever insulation level is chosen for the transformer, the working conditions and heat resistance of the other auxiliary equipment must be taken into account, not necessarily the higher the better. It is not the case that the higher the level, the better the result.

If you want to get more information about the dry-type transformer for sale, welcome to contact us.

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