New spark-gap technology with efficient line-follow current suppression for the protection of powerful LV distribution systems

Abstract

The electrical properties of low-voltage power systems (LVPS) can have a strong effect on the operational behavior of surge protective devices (SPDs) to be used for protection purposes. Besides the right selection, the qualification-testing of SPDs connected these systems has to be carried out under test conditions which meet the real operating conditions of the power systems in which these SPDs should be installed. In this regard, the “class I and Π operating duty tests” according to IEC 61643-11, chapter 8.3.4.3 is an essential test for the qualification of SPDs connected to LVPS. In this test the SPD is stressed with defined surge-current impulses while it is connected to a power system simulating the characteristic of the real LVPS in which the SPD should be installed. The focus of the work presented is laid on class I SPD based on a newly developed “line-follow current free” spark-gap technology. Fundamental aspects, like basic functional principles, construction details, the performance and also the advantages of this new class I SPD technology are presented and discussed in detail. A special focus is set on the performance of this technology in case of use in powerful LVPS with short-circuit currents up to 100 kA rms.