Design Features of the Arc-Suppressing System of an Automatic Circuit Breaker

Resumo

A method for designing an arc-suppressing system with a deionic grid in automatic circuit breakers is examined. Its essence lies in using the ratio between the characteristics of recovery strength (RS) and recovery voltage (RV) for the moment at which the arc current passes through zero. If the grid is used, the arc is divided into a number of arcs, each of which is characterized by the resistance of a partial arc. The total resistance of the arc greatly decreases the current amplitude and the shift angle between current and voltage, and, as a result, the amplitude of recovery voltage decreases and arc suppression becomes simpler. The processes for suppressing the arc in the circuit breaker in a three-phase circuit are examined. It is shown that, if the arc dies in the first suppressing pole of a three-phase circuit, a voltage triangle deforms due to the resistances of the arcs in the other two poles. When designing an automatic circuit breaker, it is recommended to use reduced coefficients (1.1–1.3 instead of 1.5). The arc-suppressing chamber allows making simpler design decisions (regarding the number and thickness of arc-suppressing plates and the distance between them), to determine the breaking ability of the automatic circuit breaker, and to optimize the parameters of the arc-suppressing system.