The existing controllable spark gap has not been able to be widely applied to the high voltage grid so far mainly due to the constraint of reliability. This paper introduces a conceptual design of a new type of controllable multi-spark gap which improves the reliability dramatically on working principle. The multi-spark gap is composed of multiple air gaps and chained R-C network for producing frequency-dependent voltage distribution along the gaps. An even voltage distribution at power frequency operating voltage while extremely uneven distribution at trigger pulse can be achieved by proper parameter setting. The even voltage distribution enables the multi-spark gap to withstand much higher voltage than that in operation, thus avoiding misfiring. In contrast, extremely uneven distribution could initiate cascade discharge at low amplitude impulse, insuring reliable triggering of the gap. The working principle of the multi-spark gap, proper parameter setting of the chained R-C network, simulation of the frequency dependent voltage distribution and its effect on the discharge voltage as well as the experimental performance verification on the prototype are presented in this paper.
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