Abstract
In this paper, combined with the characteristics of spiral-shaped transverse magnetic field (TMF) contacts and cup-shaped TMF contacts, a new structure of spiral-cup shaped contacts was designed. Firstly, experiments were carried out on two kinds of TMF contacts – the traditional cup shaped contacts and the new spiral-cup shaped contacts. Arc behaviors were recorded and the arc motion were studied. The experimental results indicated that the arc motion between new contacts was better than that between the traditional cup-shaped contacts. Here, we paid particular attention to the arc characteristics between spiral-cup shaped TMF contacts. The duration and threshold current of different stages with different tested currents were discussed, and the arc characteristics during arc motion stage was analyzed. Moreover, electromagnetic field simulation was conducted on above two kinds of TMF contacts, and the distributions of magnetic field and the electromagnetic forces acted on arc were compared. According to the simulation results, some experimental phenomena were explained theoretically. In addition, the spiral-cup shaped structure proposed here makes it possible to research on arc movement mechanism without considering the complex mechanism of arc stepping over slots.
Highlights
By producing a magnetic field perpendicular to the current, the transverse magnetic field (TMF) contacts drives the vacuum arc rotating along the contact surface, which avoids the local overheating caused by the stagnation of constricted arc
Previous studies have concluded that the arc motion is largely influenced by the gap distance, tested current, arcing time, electromagnetic force acting on arc and et al In scitation.org/journal/adv our experiments, in case of similar tested currents, arcing time, gap distance and other factors, it was found that the arc motion characteristics performed better between spiralcup shaped contacts
This might be related to the difference in magnetic field distribution and magnetic field intensity between two kinds of structures, which makes the Lorenz force acted on arc quite different, resulting in a difference in arc characteristics, especially in arc motion
Summary
By producing a magnetic field perpendicular to the current, the transverse magnetic field (TMF) contacts drives the vacuum arc rotating along the contact surface, which avoids the local overheating caused by the stagnation of constricted arc. Based on the development of contact materials, the breaking capacity of TMF contacts has been greatly improved. By producing a magnetic field perpendicular to the current, the transverse magnetic field (TMF) contacts drives the vacuum arc rotating along the contact surface, which avoids the local overheating caused by the stagnation of constricted arc.. Many scholars have made several studies on the cupshaped TMF contacts. Though experiment on cup-shaped contacts with tested current varying from 25 kA to 35 kA, Wolf found that there were obvious acceleration and deceleration during arc motion.. Zhulliying et al studied the arc characteristics between cup-shaped TMF contacts at medium frequency.. In Ref. 7, in conditions of contact gap of 5mm, transverse magnetic generated by contacts of 6.5 mT/kA and peak current of 9.3 kA, the arc run along the direction of Ampere force with the speed about 5 to 35 m/s
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