Response Time of Surge Protective Devices Employing Triggered Spark Gap Technology

Abstract

An experimental investigation of the sparkover performance of low-voltage surge protective devices employing triggered spark gap technology is made. The main goal of this study is the evaluation of the response time of three commercially available surge protective devices integrating spark gaps with gas mixture or atmospheric air, which are triggered through circuits employing resistors, metal-oxide varistors, and/or gas discharge tubes. Surprisingly, the experimentally derived response time varies beyond the upper limit (100 ns) declared by manufacturers; a variation of the response time from about 20 ns up to 20 μs is observed for a wide range of standard lightning and switching impulse voltages (2.0 kV-16.5 kV). The novelty of the study lies in i) the introduction of a response time definition for surge protective devices and ii) the proposal of a test method, that are both missing from the international standards. This work stresses the need for an update of the related standards to incorporate a definition of the response time of surge protective devices covering a wide range of transients also considering its statistical dispersion.