Influence of electrode material on pressure‐rise due to arc in a closed chamber

Abstract

SUMMARYThis paper describes the phenomenon of internal pressure-rise due to arcs ignited between metal rod electrodes in air. First, the internal pressure-rises in a closed chamber due to arcs were measured at currents within the range of 1 to 12.5 kA. The rod electrodes were made of copper, iron, and aluminum, and were 20 mm in diameter. The measurements showed that the maximum pressure-rise distinctly differed with each electrode material at the same total arc energy, namely, the maximum pressure-rise was the highest in the case of the aluminum electrode and was the lowest in the case of the iron electrode. Next, to quantitatively verify this difference, the internal pressure-rise was estimated, taking into account the energy balance in the closed chamber on each electrode material. It was found that the estimated pressure-rise approximately agreed with the above experimental results by taking into consideration oxidation reactions of the electrodes, melting and vaporization of the electrodes, and radiation loss of the arcs under certain realistic assumptions.

Experimental and theoretical investigation on radiation loss for a fault arc between different material electrodes in an enclosed air tank

“…When compared with the case without erosion, the calculated pressure rise becomes severely lower for Fe, almost unchanged for Cu, and drastically higher for Al. This is mainly attributable to the change of energy balance in the fault arc [1,3].…”

“…It may not only seriously damage the installation and equipment, but also threaten the operative's personal safety. The pressure rise due to internal arcing is seriously affected by the energy balance of the fault arc [1,2]. The fault arc dissipates a part of the power via a radiation process.…”

“…This radiation energy accounts for a significant fraction of the electrical power input into the fault arc. As a consequence, radiation plays a critical role in the energy transfer from the fault arc to its surroundings [1,3] and significantly affects the pressure rise. In addition to this, the fault arc is generally ignited between two conductive electrodes with high current and long arcing duration; a large amount of metal vapour from the electrodes will be inevitably produced and injected into the arc plasma.…”

“…Experimental studies have been made on the radiation loss of air in a fault arc. Tanaka [1] carried out experimental work to measure the relative radiation intensity of the fault arc with different electrode materials as a reference, which however, is not the actual absolute value. Fjeld [5] also measured the relative radiated energy of a high-current fault arc burning between Cu electrodes in open air under steady conditions.…”

Pressure Rise and Propagation Phenomena Due to Fault Arc in Container with Opened Pipe

“…Consequently, our institute conducted experimental studies on pressure rise characteristics in closed chambers and developed simulations for pressure rise and propagation using a CFD (computational fluid dynamics) tool. We investigated the effects of various parameters on pressure rise and propagation and confirmed that the pressure rise and propagation can be predicted by appropriate setting of such parameters, especially the percentage of arc energy contributing to the heating of air inside the chamber.…”