Abstract
The characteristics of switching DC current arcs in hydrogen containing gas mixtures under pressure were investigated using a model chamber. The switching device consists of an electro-mechanic double breaker unit with copper contacts. High-speed imaging and spectroscopy were used to observe and to characterize the switching arc. The experiments indicate how the dynamic interaction of an external magnetic field with a high-pressure discharge causes an elongation and twisting of the arc-channel and consequently a voltage increase. Comparative measurements with and without external magnetic field indicate a strong influence of this factor. Cu and N lines together with strongly broadened H lines were observed.
Highlights
The increasing use of hybrid cars and more recently the growing market of pure electric cars with batteries of increasing capacity requires the use of switching devices, contactors, of increased current interrupting capability.Recent results about DC- switching devices under H2/N2 like by Shiba, Kaneko and co-workers [1], which studied the breakdown characteristics of the H2/N2 gas mixture as well as its influence on the interrupting performance of relays, have shown that compared to air H2/N2 at 1 bar possess a higher electric strength and permits to obtain shorter arcing times
The switching device consists of an electro-mechanic double breaker unit with copper contacts
According to results of Shea [6] and Rieder [7] the influence of magnetic fields should cause, besides the elongation of the arc through Lorentz-forces, an increase of thermal losses because of the created turbulent cooling. This leads to a reduction of arc temperature and of plasma conductivity, the additional increase on arc voltage
Summary
The increasing use of hybrid cars and more recently the growing market of pure electric cars with batteries of increasing capacity requires the use of switching devices, contactors, of increased current interrupting capability.Recent results about DC- switching devices under H2/N2 like by Shiba, Kaneko and co-workers [1], which studied the breakdown characteristics of the H2/N2 gas mixture as well as its influence on the interrupting performance of relays, have shown that compared to air H2/N2 at 1 bar possess a higher electric strength and permits to obtain shorter arcing times. Suzuki and co-workers [2] presented results comparing the influence of gas (H2, N2, He and air) and working pressures (0.5 bar to 4 bar) on the arc voltage and current characteristics as well as arcing time for 100 V and 30 A DC relays. These authors found that the arcing time was shorter using H2 followed by N2, air and He, which shows up to 7 time larger arcing times than H2. Results of Volm [4] indicate improvements of arc switching performance for 1000 V and 40 A air relays by means of magnetic blowing combined with outgassing from polymer components
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