Thermal mechanical performance test on suspended insulators for transmission line
This study described some basic performance tests and accelerated ageing test by cool-heat cycling methods and thermal mechanical performance test methods on alumina porcelain insulators (new and aged) used for transmission lines in Korea. There were no failures in electrical and mechanical performance tests such as high voltage strength, flashover voltage, impact strength, etc. in any of the samples. However in the case of accelerated ageing tests above 90 /spl deg/C temperature gradient, fracture phenomena occurred by a thermal shock in the aged samples with low aluminous porcelain body. It was found that sample A was more severely aged than other samples. According to results of the HRB test and microstructural analysis, it was reasoned that insulator bodies with the matrix reinforced with alumina crystalline phase have advantages in the suppression of crack propagation. Cool-heat aging and mechanical thermal aging tests show that a temperature gradient is more effective for acceleration of the aging than variation in the number of cycles.
Failure characteristics of suspension-type porcelain insulators on a 154 kV transmission line
The paper reports on the failure characteristics of porcelain suspension insulators removed from a 154 kV transmission line in Korea. It is found that it is very important to choose the test data describing the homogeneity of porcelain, which is related to the micro-crack propagation in the porcelain body, for leveling the ageing state of the porcelain insulators. Tests such as the Rockwell hardness, is found to be effective in calculating the statistical values on the micro-crack fracture of the porcelain body. The combined thermal and mechanical tests have a close relationship to the dielectric strength of the porcelain body. The use of the Weibull distribution function is shown to be a very reasonable way of calculating the failure probability of aged porcelain insulators
Application of infrared camera to bituminous concrete pavements: measuring vehicle
Infrared thermography (IR) has been used for decades in certain fields. However, the technological level of advancement of measuring devices has not been sufficient for some applications. Over the recent years, good quality thermal cameras with high resolution and very high thermal sensitivity have started to appear on the market. The development in the field of measuring technologies allowed the use of infrared thermography in new fields and for larger number of users. This article describes the research in progress in Transport Research Centre with a focus on the use of infrared thermography for diagnostics of bituminous road pavements. A measuring vehicle, equipped with a thermal camera, digital camera and GPS sensor, was designed for the diagnostics of pavements. New, highly sensitive, thermal cameras allow to measure very small temperature differences from the moving vehicle. This study shows the potential of a high-speed inspection without lane closures while using IR thermography.