Abstract
This paper presents the results of a comparative analysis of the dielectric strength of disconnecting vacuum interrupters operating on air and helium. The breakdown voltage Ud was measured in the pressure range from 8.0 × 10−4 Pa to 3.0 × 101 Pa for air and from 8.0 × 10−4 Pa to 7.0 × 102 Pa for helium, while varying the interelectrode distance from 1.0 to 5.0 mm. Dedicated laboratory workstations were used to determine the actual pressure values in the vacuum interrupters tested and to precisely measure and record the dielectric strength results of the test object. It was found that the helium-filled vacuum interrupter maintains its full dielectric strength in significantly larger pressure ranges, while the air-filled vacuum interrupter loses its insulating properties. Thus, it is possible to make vacuum interrupters based on the working medium associated with pure helium, with larger working pressure ratings. Under such conditions, it is easier to maintain the tightness of the device and to limit cut-off currents and overvoltages associated with vacuum switchgear.
Highlights
To the case where airtowas where air was dosed into the vacuum interrupter, there was a sharp drop in the dielectric strength of the system above the pressure values specified in the table below
On the basis of the conducted tests of the dielectric strength of vacuum interrupters filled with two types of gases: air and helium, it was found that the interrupter filled with helium maintains full switching capability in a larger pressure range
The rated operating pressure of currently manufactured vacuum interrupters is approximately 1.0 × 10−3 Pa, so the insulating medium proposed by the authors of this article makes it possible to increase the pressure inside the interrupter many times
Summary
The continuously growing demand for electricity, as well as the poor technical condition of power distribution networks, force the construction of new, more technologically advanced power networks with better operating parameters, necessary for the reliable transmission and distribution of electricity to the end customers [1,2]. Taking into account the advantages and disadvantages of the used insulating media, scientists are currently working on various types of gas mixtures in order to find a compromise between proper insulating parameters and lack of harmfulness to the environment [11,12,13,14]. Such gas mixtures are often enriched with elements of chemical gases, referred to as electronegative [4]
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