Analysis of voltage oscillograms at disconnecting contacts

The paper presents detailed research of voltage oscillograms at opening contacts with currents 0.5-12 kA. The used copper-chromium electrodes 20 mm in diameter were sharpened to a weak cone to fix the contact location. The authors have developed the technique for quantitative analysis of the voltage oscillograms and have determined values of voltages and voltage derivatives describing various stages of transition to an arc: instability of the liquid metal bridge, the stage of bridge column arc (BCA) [1], as well as durations of these stages. Their studies of dependences of duration of various stages on the current have ascertained that, although destruction of a liquid bridge occurs at a random time moment, the duration of the transition process, including the stages of the bridge instability and BCA, is constant with satisfactory accuracy, for the given current and velocity of the contacts.