Due to high humidity, the ageing of room temperature vulcanized silicone rubber (RTV) has been a serious problem in Southwestern China. In order to solve the problem of RTV life prediction, the aging classification method was established by analyzing the microtopography of RTV samples in this paper. Besides, the comprehensive analysis of RTV element content, partial element content ratio, and major chemical groups of RTV samples in each aging level were conducted. It is found that as the ageing level increases, the element contents of C, Si, O, Al change accordingly and the ratio of C:Si drops from 2.39 to 1.54, and absorption peaks of the chemical groups of Si-(CH₃)₂, Si-O-Si, Si-CH₃ and C-H in CH₃ decrease. This work can enrich the investigation of RTV, and may provide useful reference for performance evaluation and replacement of RTV in substations.

The surface of organic insulating materials such as room temperature vulcanized silicone rubber (RTV) coatings often has serious contamination deposition. In humid areas such as the Southwest region of China, algae contamination layers are present on the surface of the insulators. In this study, the geographical and creeping distribution of algae contamination on the surfaces of RTV insulators were studied by investigating and sampling various substations in the Southwest region. The main components of soluble salts in the contamination were studied by atomic absorption spectroscopy and ion chromatography. The algal genome was extracted by the cetyltrimethylammonium bromide method, and the species of algae and other microorganisms in the contamination layer were determined. The effects of algae or their secretions on the surface resistance and hydrophobicity were studied by quantitatively inoculating algae and smearing extracellular secretions on the RTV surface. The damage of the algae contamination layer to the microstructure of the silicone rubber was investigated by microscopic observation and thermogravimetric analysis. Results showed that the growth of algae was positively correlated with the surface contamination of RTV. The extracellular secretion of algae destroys the surface microstructure of RTV and causes the removal of alumina hydroxide, leading to the reduction of siloxane. Therefore, the resistance and hydrophobicity of the RTV surface were reduced. It is of great significance to study the characteristics and effects of the algae contamination layer for RTV maintenance.

The operating safety of spacecraft in space environments is closely related to the surface discharging phenomenon of dielectrics such as polyimide (PI) film in solar arrays; moreover, carrier traps in the dielectric can affect its insulation performance. Therefore, to improve the vacuum surface flashover characteristics of PI film by nano modification and reveal the effect of trap distribution on the flashover of PI composite film, first, the original PI and nano-ZnO/PI composite films with different additive amounts (0.5, 1, 2, and 3 wt.%) were prepared by in situ polymerization and their performance was evaluated by the physicochemical properties characterized by methods such as thermogravimetric analysis; second, the surface traps of the original and nanocomposite films were measured and calculated by surface potential decay method, and the carrier mobility was also obtained; finally, the vacuum direct current (DC) surface flashover characteristics and bulk resistivity of all the film samples were measured and analyzed. The experiment results showed that with the increase in the amount of nano-ZnO, both the shallow and deep trap density increased significantly, while the trap energy varied slightly, and the surface flashover voltage also increased obviously. Based on the multi-core model, the increases in the shallow and deep trap density after the introduction of nano-ZnO into the PI matrix was analyzed from the microscopic perspective of the interface. Based on the comparative analysis of the trap distribution and surface flashover voltage characteristics, a bilayer model of vacuum DC surface flashover development was proposed. In the bilayer model, deep traps and shallow traps play a dominant role in the vacuum–solid interface and the inner surface of the dielectric, respectively, and increasing the trap density could effectively inhibit secondary electron multiplication on the surface and accelerate charge dissipation inside the film. Consequently, nano-ZnO can purposefully control the trap distribution, and then improve the flashover characteristics of nano-ZnO/PI composite films, which provides a new approach for improving the spacecraft material safety.

As one of the key components of the circuit breaker operating mechanism, the relay can experience performance degradation due to harsh environmental factors, such as salt spray, during operation, which can ultimately affect the normal operation of the circuit breaker and threaten the safe and stable operation of the power system. To effectively evaluate the condition of the relay operating in salt spray environments over the long term, this study conducted accelerated aging experiments on a certain model of auxiliary switch under salt spray conditions using an existing test platform. The relay’s pull-in voltage, release voltage, pull-in time, and release time were analyzed as characteristic parameters affected by salt spray. The results showed that the intrusion of salt spray caused a decline in the coil performance of the relay, which required higher voltage to provide the electromagnetic force needed for operation, leading to an increase in operating voltage. On the other hand, coil degradation also caused a decrease in the electromagnetic force generated by the step voltage, resulting in a slower operating time. Subsequently, a Genetic Algorithm_Back Propagation Neural Network GA_BP) algorithm model suitable for identifying the relay status in this study was established. After optimization by a Genetic Algorithm Neural Network (GA), the recognition accuracy increased from 78.6% to 91.8%, which showed significant improvement. By clarifying the changes in the characteristic parameters of the relay in a salt spray environment and relying on experimental data, this study established a relevant state recognition model. The research results have important engineering application value for understanding the relay operating status of the circuit breaker operating mechanism in salt spray environments, conducting circuit breaker operating mechanism relay life prediction, and preventing circuit breaker operating mechanism failures.

From laboratory experiments it was shown that the flashover voltage of the wet contaminated insulator was significantly influenced by the parameters of the local arc. An integrated optical and electrical diagnostic platform was designed in this paper, which was used to acquire the emission spectrum and electrical parameters of the AC local arc over the wet contaminated surface. The analysis of thermodynamic and electric results showed that AC local arc had a “static time-varying” feature. Hence, a new characterization method of volt–ampere characteristics of the AC local arc was proposed, and a time constant was introduced to describe the time required for the AC local arc to reach the stable state from the beginning. The relationship between the voltage gradient of the AC local arc and the leakage current amplitude was obtained for flashover voltage calculation. Special attention was also paid to the influence of environmental factors, such as air pressure and ambient temperature, on the arc characteristic. This work can enrich the investigation of the parameters of the local arc over the wet contaminated insulation surface and may provide useful parameters for flashover voltage calculation of insulators in service.