A new, intelligent digital arc detection system for air- and gas-insulated switchgear

A completely new, intelligent μC-controlled arc detection system for air- and gas-insulated switchgear has been developed. This system´s main features include high sensitivity, high operational reliability, high availability, zero maintenance, fault location with indication, along with self-monitoring (also covering the signal transmission route). High sensitivity is achieved by detecting the most striking and the fastest of physical variables indicative of an arc, i.e. its light. The light is detected by specially developed light sensor spheres facing each cladded compartment of the switchgear panel. These light sensor spheres display uniform sensitivity in all directions of the hemisphere. The light is conveyed by fibre-optics to an evaluator and converted into a digital signal by photodiodes and A/D converters. The signal is evaluated using an algorithm that incorporates auxiliary signals so as to permit unambiguous differentiation between an arc and any interference signals in order to achieve maximum reliability even where light interference signals are involved. The new arc detection system for type-tested medium-voltage switchgear makes it possible to minimize the potential duration of an arc and hence its destructive effect, resulting in enhanced safety for the switchgear environment