Anode-Circuit-Breaker Design and Performance Criteria

The arc voltage EB developed by the anode-breaker, together with its early introduction into the circuit following current reversal, constitute the most essential performance criteria. It is shown that a current zero, the first prerequisite for interruption, can be created in the arc-back circuit only by developing a counter current (iB) which neutralizes the arc-back current (1). This helpful concept is developed in a rigorous quantitative manner. The electromotive force for this counter current is the arc drop of the anode breaker (EB). Contrary to general belief, the arc energy (k) developed by the anode breaker does not necessarily decrease as the arc voltage is introduced earlier in the circuit For each arc-voltage characteristic there exists a particular time of introduction, (??e), which gives maximum arc energy. Neither can the point of minimum energy be accepted as the desirable objective due to the relatively high initial recovery voltage (E1) associated with this point. Optimum anode-circuit-breaker performance, in circuits having high rates of current rise, requires establishing the final current zero during the inverse-voltage period (E1 negative) together with arc energies (k) which avoid the peak of the energy characteristic. The modification of these results as affected by the ratio of the reactive ohms (??L) to the resistance ohms (R) of the circuit is discussed on a quantitative basis. Quantitative variations in the various parameters are presented to study their effect. Certain unique characteristics of anode breakers are explained.