H-class Dry-type Transformer

Dry Type Transformer is an insulation system based on insulating paper. It maintains excellent electrical and mechanical properties throughout the service life of the transformer. The insulating paper is not easy to age, is shrinkage-resistant and compression-resistant, and has strong elasticity, so it can ensure that the transformer coil remains tightly structured even after several years of use and can withstand the pressure of short circuits.
Main structure
1. The core is a step-by-step 45° full-bevel joint
2. The insulation between turns, layers, sections and insulation cylinders are all made of insulating paper or molded parts
3. The low-voltage coil is foil-type
4. The high-voltage coil is continuous
5. The body adopts special isolation and noise reduction measures
High-voltage coil
The high-voltage coil adopts a continuous structure with high mechanical strength and good heat dissipation conditions. The coil is wound on a molded insulation cylinder, and an insulating paper-wrapped flat copper wire is used as the conductor. The insulating material insulation paper is used between the layers. The coil is impregnated into a solid whole by VPI vacuum pressure, avoiding the shortcomings of high interlayer voltage, poor heat dissipation capacity, easy thermal breakdown and low mechanical strength of multi-layer cylindrical coils, thereby improving the reliability of product operation; it has excellent moisture resistance, can withstand thermal shock, never cracks, and has a partial discharge of <5Pc. It is easy to decompose and recycle after the life span to protect the environment.
Low-voltage coil
The low-voltage coil is a foil-wound structure. The coil is wound with high-quality copper foil and H-grade insulation material. The insulation system is made of insulating paper between layers. The coil is impregnated by VPI vacuum pressure to form a solid whole. The product structure features:
1. The coil has high mechanical strength and strong short-circuit resistance.
2. The coil has strong thermal shock resistance and improved product life.
3. The coil has strong "moisture-proof, dust-proof, and salt spray-proof" capabilities.
Core
The core material is 0.2mm thick high-quality high-magnetic conductivity silicon steel sheet with 45° full oblique overlap. The core adopts a non-punching and pull-plate structure; the surface is coated with insulating paint, which is moisture-proof and rust-proof, with low loss and low noise. The operating noise is about 16db lower than the national standard, which can meet the national first-level residential area noise requirements.
VPI
Vacuum pressure impregnation technology
①Preheating: preheat the coil to 135-150℃, keep it for several hours, take out the coil and lower the surface temperature;
②Vacuum: open the cover of the impregnation tank, put the coil in, and then close the cover to evacuate;
③Impregnation: open the release valve of the impregnation tank, put the impregnation paint to more than 50mm above the top of the coil, and close the conversion valve;
④Vacuum: evacuate again and maintain for about 30 minutes;
⑤Pressurization: close the vacuum valve of the impregnation tank; open the pressure valve of the impregnation tank and increase the pressure to 6 Pa;
⑥Drying: take out the coil and wait until the paint on the coil is completely dried;
⑦Drying: put the coil in the drying room, adjust the temperature to 135-150℃, and bake continuously for 8-10 hours;
⑧Cooling: After the coil is dried, take out the coil and cool it to room temperature, and the process is over.
Performance characteristics
High safety
SG10 transformers do not contain flammable resins, do not support combustion during use, are flame retardant, will not explode or release toxic gases, will not cause harm to the environment, other equipment and human body, are insensitive to humidity, dust and pollution; there is no partial discharge and no possibility of "cracking" during operation.
High reliability
Both high and low voltage coils are made of NOMEX insulation materials, and are impregnated with H-class solvent-free impregnation paint multiple times by VPI vacuum pressurization equipment, and are cured by high temperature baking multiple times. The product is H-class (180℃), and the main insulation material is C-class (220℃), with strong overload capacity and good short-circuit resistance. Under good ventilation, 20% overload operation is allowed.
Energy saving and environmental protection
After the product life ends, steel, iron and other materials are easy to recycle;
All NOMEX paper used will not release toxic substances when burned;
Other insulation materials can be degraded and will not pollute the environment;
The product has low loss and energy saving;
Low noise and flexible design.
Development Prospects
So far, H-class dry-type transformers have a very small share in my country's dry-type transformer market, and there are only a few influential manufacturers. Since most of my country's dry-type transformer manufacturers are imported epoxy cast structures, and this type of product has long been accepted by the majority of users, the cost and selling price are constantly decreasing. Therefore, in my country, the situation where epoxy cast manufacturers occupy a dominant position in the dry-type transformer market is unlikely to change for quite some time.
There are still some manufacturers that originally produced oil-immersed transformers and plan to manufacture dry-type transformer products. Based on the considerations of reducing initial investment and innovation, some manufacturers are planning to develop H-class products.
The future development prospects of H-class products in my country are still mainly determined by the quality and price of the products. It is undeniable that users' demand for overload capacity and the degree of acceptance and recognition of such products by users will affect their development prospects.
In the new century, with the improvement of the country's environmental protection requirements for fire safety, degradation of waste materials after the end of transformer service life, and the future direction of the country's specific environmental protection policies, H-class dry-type transformers will form a strong competitive ability in the future market competition with their advantages in environmental protection. Therefore, it is favored by manufacturers on the one hand, and gives users more choices on the other hand. I believe that in the near future, it will become more and more popular with the majority of users, and even occupy part of the traditional dry-type market. Transformers of this technology are the trend of China's future development, and there will be very broad development prospects in the future.