Suppression of contact arcs between rail and wheel in dc electric railway systems

该电触头广泛应用于宽电压、宽电流范围内。在直流电气化铁道系统中，大电流断线时轮轨间的弧光放电电流密度在短时间内极大。焊条(钢轨边缘)被强烈加热，有时会受到严重的熔化破坏，对性能有影响。本研究的目的是开发一种用于直流铁路系统的开关辅助电路，以抑制在接触开路时产生的接触弧。该电路由电压检测电路、电能吸收电路和半导体开关组成。电压检测电路通过电极之间的电压检测电弧的出现，并与电力吸收电路进行电连接。通过绕过电弧电流，该电路抑制了电弧，并防止了电极损坏。该半导体开关采用金属氧化物半导体(MOS)场效应管(FET)并联，旁路大电流具有较快的响应时间。模拟引弧实验装置由电源(大电容组)、滚动触头、导轨和电感组成。研究了钢轨在接触弧过程中的损伤情况，以及从引弧到辅助操作的延迟时间对钢轨损伤的影响。随着运行延误时间的缩短，钢轨上的弧坑或可见变化越来越小。在几十微秒的运行延迟时间内，防止了钢轨损坏。

The electrical contact is widely used within a wide voltage and current range. In dc electric railway systems, current density of an arc discharge between wheel and rail at a time of disconnecting large current is extremely large for a short time. Electrode (edge on rail) is strongly heated and sometimes suffers severe damage of melting and has an influence on performance. The purpose of this study is to develop a switching assist circuit for dc railway systems for suppressing contact arcs generated at times of contact opening. The circuit is composed of a voltage detection circuit, an electric power absorption circuit, and a semiconductor switch. The voltage detection circuit detects arc occurrence by voltage between electrodes and makes electrical connection to the electric power absorption circuit. By bypassing the arc current, the circuit suppresses arcs, and prevents electrode damage. The semiconductor switch was made using metal-oxide-semiconductor (MOS) field effect transistors (FET) connected in parallel and enabled a fast response time for bypassing large current. Experimental apparatus for simulating arc generation is composed of power supply (large capacitor bank), rolling contact, rails, and an inductance. Rail damages during contact arcs and its change by delay time between arc ignition and the assistant operation was examined. As the operation delay time becomes shorter, arc crater or visible change on the rail is getting small. At the operation delay time of several tens of microseconds, the rail damage is prevented.