Discussion on “notes on oil circuit breakers for large powers and high potentials” (Randall), Vancouver, B.C., September 11, 1913. (see proceedings for October, 1913)

L. G. Robinson: It seems to me that the subject of circuit breakers has been handled in a very masterful manner. The principles underlying the operation of the circuit breaker I agree with perfectly. The use of circuit-breaking devices dated back to the time when we used direct current almost entirely; it was found after the introduction of alternating-current circuits, that as the voltage of a circuit gradually increased, due to the necessity of longer distance in transmission and heavier loads to be carried on the circuits, that the more abrupt the opening of the circuit the better. Dr. Steinmetz some years ago published in the Institute Proceedings a very exhaustive treatise upon the effect of opening circuits abruptly, especially alternating-current circuits, and he used mathematical demonstrations and deductions to show what the effect would be in regard to oscillations caused by this sudden rupture of the current. The keynote of his deductions or summary was that you cannot open a circuit too abruptly for the reason that as soon as the current goes to the zero point in the wave form it is unable to re-establish itself and dies out naturally in the vibration.