Transformer is an indispensable and important equipment in the power system, its main function is to convert high-voltage electrical energy into low-voltage electrical energy, or vice versa, to adapt to the power needs of different voltage levels. Although modern transformer design and manufacturing technology is constantly improving, partial discharge fault is still one of the important factors affecting the safe operation of transformers. Partial discharge refers to the electrical discharge phenomenon that occurs inside the insulation material or in the local area of its surface, which will not only lead to the aging and damage of the insulation material, but also may cause more serious failures, and even lead to the failure of the transformer. This paper will discuss the typical types of transformer partial discharge faults, their causes, effects and prevention measures.

Partial discharge refers to the discharge phenomenon caused by the local electric field strength exceeding the breakdown strength of the insulating material in the insulation system of electrical equipment. Its characteristics include that the discharge occurs in a local area of the insulation material, the discharge energy is small, and usually does not lead to a complete breakdown of the insulation material. Over time, however, partial discharge can lead to deterioration of the insulation, which can lead to more serious failures. The main characteristics of partial discharge include:
1. Discharge frequency: The frequency of partial discharge is usually tens of kilohertz to several megahertz, and may vary under different working conditions.
2. Discharge signal: Partial discharge will produce electromagnetic waves and sound waves, which can usually be monitored by specific detection equipment.
3. Discharge location: Partial discharge usually occurs at the defect, interface or impurity of the insulation material.
Typical partial discharge fault types

1. Air gap discharge Air gap discharge is the most common type of partial discharge, usually occurring on the surface of the insulating material or in the internal air gap. When the electric field strength exceeds the breakdown strength of the air, the air in the air gap will discharge and form an arc. The harm of air gap discharge is mainly that it can lead to local ablation of insulation materials, thus accelerating insulation aging and reducing the service life of transformers.
2. Interface discharge Interface discharge occurs at the interface of different insulation materials, such as resin and metal or between different types of insulation materials. When the electric field intensity at the interface is too high, partial discharge will occur. Interface discharge is usually accompanied by the production of gas, which may cause the stripping and damage of the insulation material, which in turn affects the overall performance of the transformer.
3. Internal discharge Internal discharge refers to the discharge phenomenon that occurs at the defects or impurities inside the insulation material. This discharge is usually difficult to be captured by external detection equipment, but it is extremely harmful. Internal discharges can cause the insulation to deteriorate, forming tiny bubbles and cracks that can eventually lead to a complete failure of the insulation.
4. Surface discharge Surface discharge occurs on the surface of the insulating material and is usually caused by surface contamination or moisture. When the surface electric field strength is too high, the current will flow on the insulation surface, forming a discharge phenomenon. Surface discharge not only causes damage to insulation materials, but also may cause safety hazards such as fire.
Causes of partial discharge faults The causes of partial discharge faults are various, including the following aspects:
1. Aging of insulating materials: over time, insulating materials will age due to heat, humidity, mechanical stress and other factors, resulting in a reduction in their dielectric strength, which is prone to partial discharge.
2. Environmental factors: high temperature, high humidity, pollution and other environmental factors will accelerate the deterioration of insulation materials and increase the probability of partial discharge.
3. Design defects: If there are defects in the design of the transformer, such as improper selection of insulation materials, unreasonable structural design, etc., it may lead to partial discharge failures.
4. Manufacturing defects: In the production process of the transformer, if the process is improper, it may lead to defects in the insulation material, resulting in partial discharge.
Impact of partial discharge faults The impact of partial discharge faults is mainly reflected in the following aspects:

1. Reduced insulation performance: Partial discharge will lead to aging and deterioration of insulation materials, reducing their insulation performance and increasing the risk of equipment failure.
2. Shortened equipment life: Due to the existence of partial discharge, the service life of the transformer will be significantly shortened, increasing the cost of equipment replacement and maintenance.
3. Safety hazards: partial discharge may cause fire, explosion and other safety accidents, threatening the safety of personnel and the safe operation of equipment.
4. Economic losses: Equipment failure and outage will lead to economic losses, affecting the stability and reliability of power supply.
In order to effectively prevent transformer partial discharge failure, the following measures can be taken:

1. Regular detection: Regular partial discharge detection of the transformer to discover and deal with potential faults in time.
2. Improve the design: in the design stage of the transformer, fully consider the selection of insulation materials and structural design to reduce the possibility of partial discharge.
3. Strengthen maintenance: Perform regular maintenance on the transformer, clean the insulated surface, and maintain good insulation.
4. Environmental control: Improve the working environment of the transformer, reduce temperature and humidity, and reduce the impact of pollutants.
5. The use of new materials: the use of new high-performance insulation materials to improve the insulation performance of the transformer and reduce the risk of partial discharge.
Partial discharge fault of transformer is an important factor affecting the safety and reliability of equipment. Understanding its typical type, cause and influence is helpful to take effective prevention and control measures to ensure the safe operation of transformer. Through regular inspection, improved design and strengthened maintenance, the incidence of partial discharge fault can be effectively reduced, the service life of transformer can be extended, and the stability of power system can be guaranteed.