Because of light weight, high strength, composite insulator pollution flashover resistance is strong, manufacturing maintenance convenience, and many other advantages and widely used in electric power system, breaking the long-term dominance of porcelain and glass insulator.
According to incomplete statistics, in 2001 the total number of grid operation has amounted to 1. 6 million, about 2. 9 million years, in terms of using quantity, our country has become the second only to the United States of composite insulator used 2 power.
But with the increase of operation time and the quantity of information of the failure of composite insulator is gradually increasing.
According to incomplete statistics, by 1998, in east China, north China region, 15 interface breakdown accident occurred in north China, east China, guangdong 23 pollution flashover accident.
Obviously, in the improved formula and manufacturing process, improve the quality of composite insulator at the same time, targeted to carry out the operation of composite insulator detecting technology research to ensure the safe operation of power grid is of great significance.
Composite insulator in the operation of the current detection techniques mainly include: direct observation method for composite insulator external physical defects currently * for commonly used method is the direct observation method, which USES binoculars on the surface of tower under observation to find common defects such as sheath, umbrella skirt, presence of cracking, in areas such as the hardware electrical pitting, pulverization, tracking, etc. , such as the above phenomenon, it should be replaced immediately insulator.
But not enough reliable ground observation, still need to climb tower and hard to find inner insulation fault detection such as dendritic channels, etc.
Ultraviolet imaging method partial discharge can cause small but stable surface composite insulators
umbrella skirt and sheath to form carbide channel or electrical pitting.
When the insulator surface carbonization channel, its service life will be greatly reduced, even in the short term is punctured.
Using electronic ultraviolet detector can be charged due to partial discharge detection of composite insulator surface to form carbide channel and electric erosion, its principle is: the charged particles in the process of partial discharge compound emit ultraviolet light, when the insulator surface conductive channel carbide, partial discharge.
The deficiency of this method is required in the night, is operating temperature environment;
Another request is undergoing partial discharge test, this requires testing should be in high humidity and rainfall conditions.
Easily affected by viewing Angle but the test result, test equipment is also more expensive.
Infrared imaging method, infrared imaging method can detect the partial discharge, leakage current flows through the insulation material of dielectric loss and resistance loss caused by insulator local temperature, can be used in on-line detection.
Large operation composite insulator infrared thermal imaging temperature measurement census, it is found that all have obvious the insulator of local hot spot, the hot spot to the surface of silicone rubber insulator high end were significantly black, pulverization, crisp, loss of hydrophobic basically, there are many tiny cracks appear even some serious damage;
Hair hot spot to a high pressure side cannot bear power frequency withstand voltage test or steep wave impact test, known hair hot spots for the position of the progress of partial discharge in insulation interface.
Cost high and instrument is vulnerable to the sun, wind, humidity, environment temperature and some rapid changes in surface temperature factors can cause insulator is the deficiency of infrared imaging method.
Ultrasonic method by ultrasonic wave method to detect composite insulator mandrel crack.
The realization of the ultrasonic testing is based on the ultrasonic wave in from one medium into another medium of communication will occur at the interface of two medium in the process of reflection, refraction and the principle of mode conversion, launch ultrasonic generator starting pulse into the insulator medium, when the composite insulator has a crack in the timeline of the crack on the reflection, by the size and location of defect wave on the timeline to judge the defect in the insulator.
In ultrasonic testing of composite insulator mechanical defect with simple operation, safe and reliable, strong anti-interference ability, etc.
But due to the coupling, attenuation and ultrasonic transducer performance problems, has not been a major breakthrough in remote telemetry, not suitable for site test, which is mainly used for enterprise on-line detection and identification in the laboratory and production.
On a message: the three major factors effecting the reliability of insulator 】
The next message: of malfunctioning of the composite insulator in solution and prevention methods and storage 】
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