Design and implementation of fast current releasing DC circuit breaker

Interruption of DC fault current in a DC system is more complex as compared to the AC one due to the high rate of rise of fault current and absence of natural zero crossing. Fast and hard switching action in DC current interruption causes excessive voltage across the circuit breaker. This paper investigates a new type of solid-state DC circuit breaker namely current releasing DC circuit breaker. The mechanism of current interruption in the current releasing DC circuit breaker is analyzed through an aggregated model. The design procedure is defined and simulation results are presented. In addition, a sensitivity analysis is carried out. Finally, the experimental results from a lab-scale prototype as a proof of concept are demonstrated. This study confirms that the current interruption time of the current releasing DC circuit breaker is remarkably less than the typical solid-state DC circuit breakers and it requires less number of semiconductors in its main breaking branch. Although the current releasing DC circuit breaker does not have any surge arrester in its structure, its switching surge voltage is significantly limited.