Room temperature vulcanized (RTV) silicone rubber is extensively used in power system due to its hydrophobicity and hydrophobicity transfer ability. Temperature has been proven to markedly affect the performance of silicone rubbers. This research investigated the degradation of RTV silicone rubber under temperature cycling treatment. Hydrophobicity and its transfer ability, hardness, functional groups, microscopic appearance, and thermal stability were analyzed using the static contact angle method, a Shore A durometer, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry (TG), respectively. Some significant conclusions were drawn. After the temperature was cycled between −25 °C and 70 °C, the hydrophobicity changed modestly, but its transfer ability changed remarkably, which may result from the competition between the formation of more channels for the transfer of low molecular weight (LMW) silicone fluid and the reduction of LMW silicone fluid in the bulk. A hardness analysis and FTIR analysis demonstrated that further cross-linking reactions occurred during the treatment. SEM images showed the changes in roughness of the RTV silicone rubber surfaces. TG analysis also demonstrated the degradation of RTV silicone rubber by presenting evidence that the content of organic materials decreased during the temperature cycling treatment.

A reasonable acoustic power formula is vital to precisely evaluate the audible noise (AN) level of ultra-high-voltage (UHV) AC power lines. This study derived a formula by taking several AN measurements under heavy rain conditions, using multiple conductor bundles in a UHV corona cage, and then subjecting these measured values to least squares fitting. The validity of the proposed formula was subsequently verified with statistical data obtained from two long-term stations at Henan and Hubei Province, which are located under the Jindongnan-Nanyang-Jingmen UHV AC transmission lines operating at 1000 kV. The deviation between the prediction and the long-term (L50) value was 0.76 dB for the Henan station and 0.17 dB for the Hubei station. It shows that the acoustic power formula derived in this paper is more accurate than the widely used Bonneville Power Administration formula, in which the corresponding deviations are much larger (3.07 and 2.53 dB).

Radio interference (RI) induced by the corona discharge of alternating current transmission lines is more severe at high altitudes than at low altitudes; hence, RI is a crucial limiting factor in the structural design of transmission lines and environmental impact assessments. To determine RI performance at high altitudes, the State Grid Corporation of China constructed an ultrahigh-voltage (UHV) corona cage in Xining in 2015 at an altitude of 2261 m. In this study, the cage was used to investigate a high number of bundled conductors under heavy rain. An RI excitation function was derived from Xining and the effects of several variables on RI performance were analyzed. In addition, RI altitude corrections were studied by comparing the Xining data with data obtained from a UHV corona cage in Wuhan located at an altitude of 23 m. The RI correction value was verified not to be a constant value but rather one that changed with the surface electric field and bundle size. The correction values obtained in this paper could enable the RI levels of high-voltage alternating current transmission lines at high altitudes to be evaluated more precisely.

Compared with other lightning targets on the ground, the most notable feature of a wind turbine is that the blades are usually in a rotating state when lightning strikes. To study the mechanism of blade rotation influencing wind turbine on triggering lightning, lightning discharge comparison tests based on a typical 2-MW 1:30-scaled wind turbine model with an arching high-voltage electrode were conducted under different modes of stationary and rotating blades. Negative polarity switching impulses of 250/2500 μs were applied to the arching electrode. The up-and-down method was adopted for 50% discharge voltage and the discharge process was observed. The experimental results showed that under the condition of a 4 m gap, the breakdown voltage decreases and the connection point of the leaders approaches the high-voltage electrode with increasing blade speed, indicating that the wind turbine’s blade rotation enhances the triggering of lightning. The analysis showed that the blade rotation could be altering the charge distribution on the blade tip, resulting in varied ascending leader development on the blade tip, which affected the discharge development process.

The audible noise (AN) induced by corona discharge of AC transmission lines is more severe at high altitudes than at low altitudes; this has become a crucial limiting factor for the structural design of power lines and their environmental impact assessment. To determine the altitude effect and correction of AN level for AC power lines, a corona cage test system was used to measure the acoustic power level of four bundled conductors at five elevations, namely Wuhan (23 m), Tianshui (1100 m), Xining (2261 m), Gonghe (2943 m), and Yangbajain (4300 m). We obtained the AN characteristics for different altitudes, bundle numbers, and subconductor diameters through a statistical analysis of measured data. The analysis and comparison results indicate that the actual AN correction values are slightly less than the Bonneville Power Administration term of 1 dB/300 m at altitudes below 3200 m. Above 3200 m, the difference increases gradually. A correction term 2.85 dB/1000 m is recommended for more accurate evaluation.