The main function of the insulator is to provide mechanical fixation and electrical insulation of electrical equipment and conductors on the power line. At present, three types of insulating materials are mainly used, namely ceramics, tempered glass and organic composite materials. Development has played an important role.
Porcelain insulators are composed of three parts: an iron cap, a porcelain part and a steel leg. The iron cap is ductile iron, the steel leg is low carbon steel, and the iron part and porcelain part are glued with cement. The iron cover and steel leg of each insulator are insulated. Porcelain insulators are mainly divided into three types according to the direction of use: one insulator is used in the power line, the other insulator is used in the electrical equipment of the power plant, and the insulating parts used in other charged bodies will also use porcelain quality insulators. Porcelain insulators mainly play an insulating role when connecting conductors and components in different positions.
It should be noted that insulators provide support and insulation for power lines, so the requirements for both mechanical strength and dielectric strength are relatively high, and the natural environment in my country is relatively difficult, and porcelain insulators are mainly used outdoors or even in the wild, so it is also required that porcelain insulators can adapt to difficult environmental conditions.
In addition, porcelain insulators are mainly used for high voltage power lines, extra high voltage power lines and the external insulating part of electrical equipment in power plants, so they must have high external insulation performance.
According to the above requirements, at present, in my country, the traditional methods for detecting insulators are mainly the ball discharge method, the infrared thermal imager detection method, and the leakage current detection method.
(1) Ball discharge method: By measuring the distance when the balls at both ends of the insulator are discharged, the voltage distribution of the insulator is analyzed to determine whether the test insulator is normal. This method requires frequent adjustment of the distance between the balls to analyze the voltage distribution of the insulator to determine if the insulator being tested is normal. This method requires frequent correction of the distance to the ball, and the probability of misjudgment is relatively high.
(2) Infrared detection method: The surface temperature of poor insulators differs from that of good insulators, which can be displayed on thermal images with infrared thermal imagers, but this method is difficult to use in the field. .
(3) Leakage current detection method: The insulation resistance value of defective insulators will be greatly reduced, and leakage current will be generated. By measuring the leakage current with a current sensor, determine if it is in good condition.
Summarizing, these methods have their advantages and disadvantages, but they all have a common drawback, that is, they are all qualitative tests that cannot reliably reflect the resistance value of each insulator and cannot identify a leak, but still not affected Wearing insulators that are in a state of critical damage.