Analysis of air decomposition by-products under four kinds of partial discharge defects

The partial discharge (PD) is one of the most common phenomena in power system and it is known that the discharges in the air can produce by-products such as Ozone and NOx gases. Analyzing air decomposition gases can be a potential method in PD detection. To monitoring PD and recognizing PD types by analysis air decomposition products the decomposition characteristics of air under four different kinds of PD needed to be investigated. In this paper a test cell and four kinds of artificial defects have been designed to simulate the air decomposition phenomenon under PD in electrical apparatus. A gases measurement system was established to detect the decomposition gases: O3 and NOx. Experiments of four types of PD simulated by artificial defects with several applied voltages were carried out and the PD and by-products gases were measured simultaneously using pulse current method and Ultraviolet (UV) absorption method. The temperature and pressure were kept constant during testing. The results show that the decomposition characteristics of air under four kinds of PD fault were different in terms of gases concentrations, generation rate and concentration ratios which leads to an indirect way for monitoring and recognizing partial discharge by measuring and analyzing incremental air decomposition by-products.