Abstract
In this paper, the author will take a closer look at the peculiarities of the establishment of the entire pre-commutation current that takes place during switching processes in electrical circuits and transient processes that follow. A mathematical model of the current is given, comprising the sinusoid and the aperiodic current, along with the values which define its magnitude: the switching moment, the property of loads and the ratio of R/L. It is demonstrated that current that occurs pre-commutation can easily be greatly higher than nominal currents, posing more thermal and mechanical strain on power-engineering equipment. Graphical dependencies are given that shows the effect of the damping factor as well as the initial switching phase on the waveform and maximum current values. The research points out that full pre-commutation current consideration is a critical factor in the choice of switching equipment and establishing the breaking capacity of circuit breakers.
References
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