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During the opening and closing process of the contact, it will undergo repeated arc ablation and wear. After each ablation and wear, the composition, performance, and shape of the contact surface constantly change, leading to cracks, slag drop, melting, evaporation, and other phenomena on the contact surface, ultimately causing the contact to fail, resulting in the switch not being able to open and close normally. In order to study the failure mechanism of arc contacts caused by arc erosion after breaking short-circuit current, a pair of arc contacts for the cumulative breaking short circuit current test was selected as the research object. The metallographic, microscopic morphology, and energy spectrum analysis of the arc contacts were conducted, and the analysis results were compared with the new arc contacts to reveal the evolution and development process of arc contacts from cumulative arc erosion to failure during breaking.

In recent years, bird droppings flashover faults frequently occur on transmission lines. Based on the existing conditions of the laboratory, this paper explores the flashover mechanism of 110 kV bird droppings. A new type of bird droppings propulsion device was designed and developed, and the process of bird droppings falling in the natural state was simulated without voltage. According to several typical forms of bird droppings, the main findings are ① the bird droppings connected to the two poles are the most serious short circuit situation; ② the bird droppings flashover fault of the 110 kV line is actually a single-phase grounding fault of the line through a resistance, and the grounding resistance is between 20 and 300 kΩ; and ③ the conductivity is the most sensitive factor affecting bird droppings flashover.

Under the action of 30 mA leakage current, in order to study the influence of atmospheric corrosion behavior on metal materials of transmission lines, this article analyzes the corrosion weightlessness of metal materials under different SO2 concentrations and leakage current conditions by placing metal materials in three corrosive environments. When the content of SO2 is relatively small, the leakage current has little effect on the corrosion weightlessness of the sample. However, when the content of SO2 is relatively large, the leakage current accelerates the corrosion of metal materials, and the surface of the sample will have more γ-FeOOH metastable crystalline phase. When the corrosion products accumulate to a certain extent, some of the corroded samples γ-FeOOH become relatively stable α-FeOOH and Fe3O4, the corrosion products will reduce the occurrence of corrosion phenomena, and on the contrary, the corrosion resistance of the sample will be improved.

The infrared thermal image detection method has unique advantages in the field of low zero value diagnosis of porcelain insulators. However, since the length of the extra–ultra-high voltage (EHV–UHV) porcelain insulator string can reach more than 10 m, it is difficult for common industrial thermal imagers/airborne lenses to clearly capture the infrared spectrum of the full string of EHV–UHV porcelain insulators. In order to solve this problem, this paper proposes a two-segment temperature curve splicing method based on weighted data fusion. The method avoids the problem of missing targets existing in conventional infrared image splicing methods and has higher fitting accuracy than curve splicing methods such as rounding splicing and midpoint splicing. This paper takes a 1000 kV insulator string as an example to illustrate the basic algorithm and process of the proposed curve splicing method and takes a 500 kV insulator string as an example to carry out a comparative study of various curve splicing methods, which verifies the effectiveness and feasibility of the proposed method.

In this paper, aiming at the application of geological disaster monitoring of transmission lines, by analyzing the data quality and positioning accuracy of Beidou original observation data, the influence of the electromagnetic environment of transmission lines on Beidou satellite monitoring data is obtained. According to the Beidou monitoring data of 500 kV transmission line for 23 days, the analysis results show that: in the case of strong electromagnetic interference/no electromagnetic interference, the difference of data integrity is less than 1%, the difference of multipath effect is less than 0.1 m, the difference of signal-to-noise ratio is less than 0.3 dB Hz, and the difference of cycle hop ratio is less than 150. The relative difference in positioning accuracy is less than 5%. In general, the electromagnetic environment of transmission lines has no significant impact on the data quality and positioning accuracy of Beidou deformation monitoring.

The power penetration line of high-speed railway adopts all-cable lines, and its failure will seriously affect the safety and reliability of railway transportation. The accurate location of the fault will greatly reduce the range of finding the cable fault point and the workload of cable fault repair, shorten the maintenance time, and improve the reliability of high-speed railway power supply. This paper introduces the current situation of power line fault location, analyzes various traveling wave location principles and the traveling wave transmission and attenuation characteristics of all-cable penetration lines, and analyzes the adaptability of the traditional traveling wave location technology in all-cable penetration line fault location. It is proposed that the distributed traveling wave location method can greatly reduce the transmission distance of fault traveling waves and can effectively reduce the influence of attenuation and distortion in the traveling wave transmission process. For different types of fault traveling waves, different fault transition resistances, and different positions of fault points, the method can achieve the accurate location. The practical application case shows that the technology has high location accuracy and meets the requirements of a precise location.

When the circuit breaker is switched on and off, the phenomenon of arc ablation will occur. Under the action of the electric arc, the surface of the contact is constantly damaged, resulting in deformation and material evaporation. With the increase in the electric arc temperature, the material loss on the contact surface of the circuit breaker increases. In this paper, according to the three major factors affecting the electrical life of the circuit breaker arc extinguishing chamber—the state of the arc contact, the nozzle, and the SF6 gas—the corresponding test detection methods and evaluation methods are proposed. With the continuous accumulation of the breaking current, the effective contact displacement between the arc contacts decreases and the average contact resistance increases. The effective contact displacement decreases exponentially with the increase in the cumulative breaking energy. The content of CF4 can be used not only to characterize the discharge ablation on the surface of the nozzle insulating material but also to characterize the discharge decomposition degree of SF6 in the system by adding carbonaceous compounds. Through the experiment, it is suggested that CF4 should reach 600 µl/l as the threshold for judging whether the arc extinguishing chamber needs maintenance. This method can be extended to the working condition evaluation of the arc extinguishing chamber of other types of the SF6 circuit breaker.

In recent years, unmanned aerial vehicle (UAV) inspection has become one of the main means of daily operation and maintenance of overhead transmission lines. Since the key components of the UAV inspection system are composed of electronic components, it relies on data communication to realize data link transmission. In the actual operation process, the complex electromagnetic field environment has an obvious impact on its control and communication performance, especially when inspecting near the DC line. In this paper, combined with the research on the safety assurance technology of UAV inspection operations, the electromagnetic field simulation model of the UAV inspection operation on DC transmission lines is established. The electromagnetic field distribution around the wire is analyzed when the UAV is at different inspection distances, and the influence range and degree of the DC electromagnetic field on UAV inspection system are obtained. A true test platform for the inspection safety distance of the ±500 kV line UAV inspection was built, and the inspection safety distance test and research of the small rotary-wing UAV with a typical size, structure, and material was carried out. Through the test, when the current of the transmission line is 3 kA, the minimum safety distance of the UAV inspection operation of the ±500 kV DC transmission line straight tower is 3 m, and the distance is corrected in combination with the current. The research results of this paper can provide technical support for the inspection operation of small multi-rotor UAVs on ±500 kV transmission lines.

The prebreakdown current flowing in a lasertriggered vacuum switch (LTVS), investigated in this paper, is below the threshold voltage, where the switch becomes conducting. The laser irradiates in a short time the sintered KCl and Ti target of the vacuum switch and produces an initial plasma. The prebreakdown currents are measured in two different electrode geometries (planar and multirod) at both polarities and analyzed with respect to the ion and electron interactions with the electrodes. It is found that the peak value of the prebreakdown current increases with the applied voltage across the LTVS until 60 to 80 V, where it turns instantly into the conducting state. The multirod and planar LTVSs show different prebreakdown currents at different polarities, which is related to the condition of becoming conducting. [ABSTRACT FROM AUTHOR]

A laser-triggered vacuum switch (LTVS) is an advanced closing switch with nanosecond delay and jitter. In order to enhance hold-off voltage and extend the service lifetime of an LTVS, we designed a multichannel laser-triggered vacuum switch (MLTVS) utilizing a cone-shaped target electrode placed on the cathode platform. The fabrication and testing of the MLTVS is described in this paper. Experimental results show that the working voltage of the MLTVS with a gap distance of 12 mm is from 30 V to 20 kV. The threshold energy for triggering the switch is 0.4 mJ corresponding to a peak power density of 27.9 MW/cm2. The triggering lifetime of a spot can reach up to 18 000 shots. In addition, the relationship between triggering lifetime and target materials is analyzed using a field emission scanning electron microscope. A hypothesis of the vacuum gap's triggering mechanism is discussed based on the measured results. [ABSTRACT FROM AUTHOR]