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Reference: ISH2015_658

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The correlation of external partial discharges and the voltage withstanding of medium voltage pin insulators



This paper studies the correlations observed in the dry leakage current shape and the voltage withstanding of medium voltage pin insulators. The development was based on laboratory tests on roughly 1,500 insulators obtained from a field research aiming at detecting prone to failure insulators, in operation, in over head medium voltage lines, in four different regions of Brazil. Field inspection methods were applied for inspection of overhead medium voltage distribution lines, and according to this research, for medium voltage levels, the best approach considers the application of ultrasonic and radio frequency detectors (antennas). Detecting equipments based on infrared and ultraviolet techniques, at least for the voltage level of 15 kV, the range of the present research, were not effective. The meaning of effective, in this research, is the ratio of truly detected prone to failure insulator (faulty insulator) by the total number of possible prone to failure insulators, as detected by the field inspections. Faulty insulators were determined by a failure on only one of a set of laboratory tests or by means of visual inspections. Therefore, in the present research the insulators were inspected on field by radio frequency and ultrasound antennas, removed from the pole, sent to laboratory and tested. In laboratory the insulators were submitted to the dry leakage current, wet withstanding and wet sparkover voltage tests. The correlation between field detection results and test failures define a prone to failure, or even, a faulty insulator. During the dry leakage current determination, it was recorded the shape of the total leakage current. This paper presents a short view on the testing set up, the acquisition system for recording the leakage current, at first, in laboratory and the obtained statistical correlations. Finally, this technique can be useful for application in laboratory as a subsidiary tool, also a further development for field applications.

File Size: 221,9 KB

Year: 2015

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