Abstract
This paper presents the results of testing the electrical strength of an insulating system in a vacuum obtained from three noble gases: argon, neon, helium, and air. The breakdown voltages were measured for contact gaps of 1 mm and 2 mm. A difference was observed in the pressure range where the electrical strength was kept constant. The chamber filled with helium residual gases lost its insulating properties at the highest pressure among the tested gases (2.00 × 100 Pa at contact gap d = 2 mm), while the chamber filled with argon gas lost its insulating properties at the lowest pressure among the tested gases (2.00 × 10−1 Pa at contact gap d = 2 mm). After a decrease in electrical strength, an intense glow discharge was observed. A theoretical description related to the initiation of an electrical breakdown in vacuum insulating systems is also presented. The situation in which the discharge chamber with a contact system was filled with the mentioned gases was analyzed. The mean free paths of the electrons and molecules as well as the velocities and energies of the electrons accelerated by the voltage applied to electrodes were calculated. The obtained results were related to the measurement parameters and analyzed in terms of the discharge development. The results of the research suggest alternatives for the further development of vacuum-extinguishing chambers used in environmentally-friendly electrical switchgear by increasing the rated operating pressure, maintaining the required electrical strength values, and thus facilitating the operation due to greater certainty in regard tomaintaining the integrity of such a vacuum interrupter.
Highlights
Current Research Directions Related to Low Pressure Gas DischargesThere has been considerable interest in the use of vacuum technology as an insulating medium in power switchgear
The electrical strength of the vacuum insulating system was investigated for air and electrical of theand vacuum insulating investigated air and threeThe noble gases:strength argon, neon, helium, for twosystem contactwas gaps d equal tofor
Theanalysis analysisofofthe theelectrical electricaldischarge dischargeinitiation initiationininvacuum vacuuminsulation insulationsystems systemswith with residual gases in the form of air and noble gases such as argon, neon or helium allowed us to residual gases in the form of air and noble gases such as argon, neon or helium allowed determine the boundary conditions concerning the discharge development mechanisms in us to determine the boundary conditions concerning the discharge development mechathese was found that found amongthat the studied residual gases, helium has the highest nismssystems
Summary
There has been considerable interest in the use of vacuum technology as an insulating medium in power switchgear. The authors of this paper have focused on lower pressure values (higher vacuum) at which the electric strength reaches a constant value and the strength curve flattens out At such pressure values, the probability of the development of electron avalanches at the initiation of an electrical breakdown is significantly reduced. The projected direction of research on the application of electroinsulation gases in vacuum interrupters mainly involve mixtures of sulfur hexafluoride with helium, argon, nitrogen, tetrafluoromethane (CF4 ), or hexafluoroethane (C2 F6 ) [13]. Both sulfur hexafluoride and the aforementioned perfluorocarbons increase their temperature while residing in the atmosphere and create a greenhouse effect. The idea of using a vacuum as an insulating medium is to take advantage of the fact that when the gas pressure is reduced to a value at which the average free paths of molecules and electrons are greater than the contact gap in the insulating system, the development of electron avalanches that initiate discharges in gases is impossible [15]
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