Investigation of the thermal transfer coefficient by the energy balance of fault arcs in electrical installations
Investigation of the thermal transfer coefficient by the energy balance of fault arcs in electrical installations
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DOI：
10.1109/tpwrd.2005.852274
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发表时间：
2006
影响因子：
4.4
通讯作者：
Xiang Zhang;G. Pietsch;E. Gockenbach
中科院分区：
文献类型：
--
作者：
Xiang Zhang;G. Pietsch;E. Gockenbach
为了确定电气装置中故障电弧引起的压力上升，必须知道加热故障电弧周围气体的能量部分。本文采用能量与电能的比值，即文献中所称的传热系数k/sub p/-factor。本文提出了一种计算电气装置中传热系数k/sub p/和确定压升的理论方法。它是建立在基本的水力和热力学守恒方程的解的基础上，考虑到金属的熔化和蒸发以及与断裂带周围气体的化学反应。封闭电弧室的结果表明，绝缘气体的种类、电极材料的种类、试验容器的尺寸、气体密度等因素对热传递系数有较大影响，从而导致压力升高。此外，以一个具有重金属蒸发的紧凑型中压站的短路为例，证明了数学方法是评估压力发展的可靠工具。
In order to determine the pressure rise due to fault arcs in electrical installations, the portion of energy heating the surrounding gas of the fault arc has to be known. The ratio of the portion of energy to the electrical energy, the thermal transfer coefficient, well known in literature as k/sub p/-factor, is adopted here. This paper presents a theoretical approach to calculate the thermal transfer coefficient k/sub p/ and to determine the pressure rise in an electrical installation. It is based on the solution of the fundamental hydro- and thermodynamic conservation equations taking into account melting and evaporation of metals as well as chemical reactions with the surrounding gas of the fault arc. The results for closed arc chambers show that factors such as the kinds of insulating gas and of electrode material, the size of the test vessel, and the gas density considerably influence the thermal transfer coefficient and thus the pressure rise. Furthermore it is demonstrated, with an example of a short-circuit in a compact medium-voltage station with heavy metal evaporation, that the mathematical approach is a reliable tool to assess the development of pressure.