VI-characteristics of the stationary arc in air; their use for calculation of the duration of drawn short arcs

Abstract

The voltage-current charateristics are termed VI-characteristics. They are curves in which the voltage, V, of the arc is plotted against the current, I, with the arc length as a parameter. They constitute an endorsed means of illustrating properties of an arc1. In order to avoid complications by insignificant circumstances, we shall describe the characteristics under slightly simplified conditions. We suppose that the arc at every instant is in a stationary state: Thus, its dependence on the rate of change of current and the opening speed may be neglected1. The influence the shape of the electrodes is also neglected2. These simplifications permissible owing to the rough approximations. The approximations are in turn justifiable due to the rather great spread of observed arc durations and with respect to the uncertainty of the circumstances et with in the practical work on switches for which we wish to predict the average behavior of arcs in switches. The observations refer to arcs shorter than 2 mm. Longer arcs seldom appear in communication relays delt with here.