Dry type Transformer

　　Dry Type Transformer Overview

　　A dry type transformer is a transformer that relies on air convection for cooling. Unlike oil-immersed transformers, it does not use transformer oil as an insulation and cooling medium. With advantages such as high safety and reliability, easy maintenance, and environmental protection and energy conservation, it is widely used in numerous fields.

　　Structural Components

　　Iron Core: It is usually laminated with high-permeability cold-rolled silicon steel sheets. Its function is to form the magnetic circuit of the transformer, converting the electrical energy of the primary winding into magnetic energy and then transmitting it to the secondary winding. A high-quality iron core can reduce hysteresis loss and eddy current loss, thereby improving the efficiency of the transformer. For example, some high-performance dry type transformers adopt oriented silicon steel sheets, which have better magnetic permeability.

　　Windings: Generally wound with copper or aluminum conductors, they are the electrical circuit part of the transformer. According to different insulation structures and cooling methods of the windings, they can be divided into encapsulated windings and non-encapsulated windings. Encapsulated windings are cast and encapsulated with materials such as epoxy resin, featuring good insulation performance and mechanical strength. Non-encapsulated windings are directly cooled by air and have better heat dissipation performance.

　　Insulating Materials: They are used to ensure electrical insulation between windings and between windings and the iron core. Common insulating materials include epoxy resin and glass fiber. Epoxy resin not only has good insulation performance but also can fix the windings and play roles in moisture-proofing and dust-proofing.

　　Enclosure (Optional): Some dry type transformers are equipped with an enclosure to protect the transformer from the external environment, such as preventing dust and foreign objects from entering. At the same time, it can also provide a certain degree of protection to prevent personnel from accidentally touching live parts. The enclosure is usually made of metal materials and is equipped with vents to ensure heat dissipation.Technical Characteristics

　　High Safety and Reliability: Since there is no transformer oil, there are no safety hazards such as oil leakage and fire. It is suitable for places with high fire protection requirements, such as high-rise buildings, subways, and airports. For example, in high-rise buildings, the use of dry type transformers can effectively avoid the spread of fires caused by transformer failures, ensuring the safety of personnel and property.

　　Easy Maintenance: The daily maintenance workload is small, and there is no need for regular oil sample testing, oil replacement, and other operations. Generally, it is only necessary to regularly check the operating status of the transformer, clean the surface dust, and tighten the connecting components.

　　Environmental Protection and Energy Conservation: It does not produce oil pollution during operation and is environmentally friendly. At the same time, the no-load loss and load loss of dry type transformers are relatively low, which can effectively reduce energy consumption. For example, dry type transformers that adopt new iron core materials and optimized winding designs can reduce losses by 10% - 20% compared with traditional transformers.

　　Strong Short-Circuit Withstand Capability: The winding structure is specially designed, with good mechanical strength and electrical stability, and can withstand large short-circuit current impacts, reducing transformer damage caused by short-circuit faults.Performance Parameters

　　Rated Capacity: It refers to the apparent power that the transformer can continuously output under rated voltage and rated current, with the unit being kVA. Common rated capacities include 50kVA, 100kVA, 200kVA, 500kVA, etc., and can be selected according to the actual electrical load requirements.

　　Rated Voltage: It includes the rated voltage of the primary winding and the rated voltage of the secondary winding, with the unit being V or kV. The rated voltage of the primary winding should match the voltage of the power supply grid, and the rated voltage of the secondary winding is determined according to the voltage requirements of the electrical equipment.

　　Voltage Regulation: It indicates the degree of change in the output voltage of the secondary winding from no-load to full-load. The smaller the voltage regulation, the better the voltage stability of the transformer. Generally, the voltage regulation of dry type transformers is within ±5%.

　　Insulation Class: It reflects the heat resistance performance of the transformer's insulating materials. Common insulation classes include Class F and Class H. The maximum allowable temperature of Class F insulating materials is 155°C, and that of Class H insulating materials is 180°C. A higher insulation class can improve the overload capacity and service life of the transformer.