Instability of electric circuits

An outline of a theory and classification of instability in electric circuits is given, divided into three types: 1. The transients resulting from the readjustment of the stored energy to changed circuit conditions. 2. Unstable electrical equilibrium; that is, the condition in which the effect of a cause increases the cause. This is illustrated by the electric arc on constant potential, and the induction motor within certain speed ranges and loads. 3. Permanent instability resulting from a combination of circuit constants which can not co-exist. This is illustrated by the arcing ground on a transmission line, and by the hunting of synchronous converters, and the phenomena of continuous and cumulative oscillations. It is shown that such phenomena require an energy supply resulting from a lag of the effect behind the cause, or a hysteresis cycle, and frequently involve a frequency transformation. The phenomenon of hunting of synchronous machines, and the mechanism of the transfer of the hunting energy from the supply power, then is treated explicitly, as an illustration of the general character of these phenomena.