With the rapid development of the power industry, the scale of the power grid continues to expand, the single-unit capacity and installation capacity of power transformers continue to increase, and the voltage level also continues to increase. In recent years, although the operation reliability rate of power transformers has been improved due to the improvement of materials, design methods and power transformer china manufacturing technology, unexpected accidents still occur.
(1) Failure of oil-immersed transformers due to unreasonable design, poor manufacturing quality, and defects in transportation and installation;
(2) Improper operation and maintenance;
(3) Abnormal voltage;
(4) Insulation aging. On the one hand, this is caused by the natural aging of the insulating material; on the other hand, when the transformer is overloaded or some abnormality occurs inside (such as partial discharge, partial overheating, etc.), it will accelerate the aging of the insulating material of the transformer, thereby causing Fault;
(5) Natural disasters, small animal accidents, etc.
The power transformer is one of the most important electrical equipment in the power system, and the oil-immersed power transformer is the most widely used power transformer at present. Its failure will cause significant harm and impact to the power system and users. Therefore, it is of great significance to reduce and prevent the failure of oil-immersed power transformers.
The faults of oil immersed type power transformers are often divided into internal faults and external faults. Faults may occur in different parts of various components such as iron core, windings, leads, tap-changers, bushings and ancillary equipment. Transformer faults may be widespread, global, or local. In terms of nature, oil-immersed transformer faults can be divided into mechanical faults, thermal faults and electrical faults.
Mechanical faults include vibration, broken wire strands, winding deformation, loose pads, and damage to porcelain sleeves. Thermal faults are usually local overheating and temperature rise inside the transformer. Electrical faults usually refer to the faults in which the insulation performance decreases or deteriorates under the action of high electric field strength inside the transformer.
The scientific classification of oil-immersed transformer faults will help us to effectively analyze the reasons for the occurrence and development of transformer faults, and help us to diagnose and locate transformer faults. However, the generation and development of transformer faults is a very complex process, and the nature and types of faults are not the same. Some manifest as thermal faults, some manifest as electrical faults, and some reflect overheating faults and electrical faults at the same time. . These failures may interact with each other, transforming and exacerbating the failure.