Search

The study examines the effect of neutron and gamma radiation on commercial gas surge arresters. The research is of experimental-theoretical nature. The experimental part of the research was performed un-der well-controlled laboratory conditions. The combined measurement uncertainty was about 5%. The experimental system is specially designed for the observed problem and has certain original solutions. The test procedure was fully automated and had software support in the experiment management and also for data collection and statistical processing. The obtained results show that neutron and gamma ra-diation improves the functional characteristics of gas surge arresters with a memory effect. The obtained results are explained in accordance with the theory of interaction of neutron and gamma fields with ma-terial and with the theory of electric discharge in gases. The results presented in this study are important for the design of surge protection in systems that can be found in the field of neutron and gamma radia-tion because they can achieve a positive synergistic effect of protection in hybrid schemes with other components for surge protection whose characteristics spoil this radiation. [ABSTRACT FROM AUTHOR]

The results presented in this article relate to the study of the impact of gamma radiation on the breakdown voltage of gas-filled surge arrester manufactured by CITEL, Littelfuse and EPCOS at an operating voltage of 230 V. Radium was considered as a source of gamma radiation in this research. The stability of breakdown voltage as well as the reliability of gas-filled surge arresters of different manufacturers were investigated using different statistical methods. This gas component operation was based on processes that lead to electrical breakdown and discharge in gas. The breakdown voltage has a stochastic nature, and it is a subject of certain distribution. One thousand voltage measurements of breakdown voltage were carried out for each value of the voltage increase rate, from 1 V/s up to 10 V/s, with and without the presence of additional gamma radiation. The detailed statistical analysis of the obtained experimental data was performed for both cases for all three GFSA types. Moreover, the cumulative distribution functions of breakdown voltage were presented with the applied Weibull distribution fit. The coefficient of correlation as well as Pearson χ2 test showed the strength of the relationship between the experimental distribution functions and the Weibull distribution fits. The values of the Weibull distribution coefficients for all voltage increase rates and for all components were also analyzed with and without gamma radiation. [ABSTRACT FROM AUTHOR]

Examination of electrical breakdown time delay t d as a function of relaxation time τ and analyzing of processes in insulating gas responsible for delay response of commercial gas-filled surge arresters (GFSA) manufactured by CITEL, SIEMENS and EPCOS was performed. It was shown that positive ions remained from previous breakdown and discharge, as well as positive ions formed in post discharge have a dominant role in breakdown initiation up to τ ≈ 1.5 s . In this case delay response is determined only by formative time in insulating gas. In insulating gas of GFSA manufactured by CITEL in the 1.5 s < τ < 3.10 3 s interval the dominant role in breakdown initiation is due to long living electrically neutral active particles and delay response is determined by statistical time delay. The irradiation of these devices with low doses of gamma rays leads to decrease in delay response down to the values which correspond to formative time in insulating gas. Presented results show that full relaxation of processes in insulating gas after breakdown and discharge ceases for GFSAs manufactured by SIEMENS and EPCOS occur for τ ≈ 200 ms , while for GFSAs manufactured by CITEL such relaxation occurs for about 3.10 3 s . [ABSTRACT FROM AUTHOR]

This paper investigates the stabilization of electrical discharges in gases by means of external ionizing radiation. Discharges in a gas-filled surge arrester model were studied in both passive and active regimes of the device. An originally developed model of the gas-filled surge arrester was used. Gas pressure and the interelectrode gap were the variable parameters in our measurements. Applied radiation types included α-particles, γ-rays, X-rays, and neutrons. Measurements were performed under highly controlled laboratory conditions. The combined measurement uncertainty of the applied procedure was estimated as being under the 5% level. The results obtained are followed by a theoretical explanation. The crucial result is the conclusion that ionizing radiation does not necessarily degrade the gas-filled surge arrester’s functionality but that it, rather, improves it under certain conditions.

The aim of this paper is to present the influence of electrode system parameters on electrical breakdown of gas (electrode effect) with the purpose to improve the gas-filled surge arresters (GFSAs) protective characteristics with the most optimal way. The influence of the electrode parameters on the pulse shape characteristics is examined. As variable parameters, the electrode material and the manner of electrode surface processing are used. The originally developed GFSA model with a composite electrode system enables a high degree of over-voltage protection without environmental contamination. [ABSTRACT FROM AUTHOR]