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

电触头广泛用于宽电压和电流范围内。在直流电气化铁路系统中，在断开大电流时，车轮和轨道之间的电弧放电的电流密度在短时间内非常大。电极（钢轨边缘）受热强烈，有时会遭受严重的熔化损坏，影响性能。本研究之目的在于发展一种直流铁道系统之切换辅助电路，以抑制接点断开时所产生之接触电弧。该电路由电压检测电路、电力吸收电路和半导体开关组成。电压检测电路通过电极间的电压检测电弧的发生，并与电力吸收电路电连接。通过旁路电弧电流，电路抑制电弧，并防止电极损坏。半导体开关使用并联连接的金属氧化物半导体（MOS）场效应晶体管（FET）制成，并且能够快速响应时间以旁路大电流。模拟电弧产生的实验装置由电源（大电容器组）、滚动触头、导轨和电感组成。研究了接触电弧对钢轨的损伤及其随引弧时间和辅助操作时间的变化。随着操作延迟时间变短，钢轨上的弧坑或可见变化变小。在几十微秒的操作延迟时间内，防止了轨道损坏。

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.