This thesis describes the results of an investigationof the arc end glow discharges occurring between the contactswhen an alternating current is interrupted by an oil circuitbreaker; and a comparison with similar phenomena in thevacuum circuit breaker is made. This investigation was madeby taking cathode-ray oscillograms of the variation ofvoltage across the contacts, and the current through thedischarge, with time, and the variation of the voltage acrossthe contacts with the current through the discharge. Circuitvoltages of 15,000 and 2300 were used, and currents up to45 amperes were interrupted.
The discharges across the separating contacts of anoil circuit breaker are discussed in detail, and an analysisof the variations near the zero of the current wave is made.This investigation shows that for a brief period, of theorder of 300 microseconds, at the end of each half cycle ofthe current wave the current between the contacts is of a verysmall magnitude, and may be considered essentially zero. Duringthis interval the voltage completes a part of an oscillation,the frequency of which is apparently determined by the constantsof the connected circuit, and rises in the reverse directionuntil a certain maximum is reached. After this value is reachedcurrent again flows end the usual glow and arc phenomena areobserved.
