Interaction between test circuit for generation of secondary arcs and short-circuit test transformer

Abstract

This work has its origin from research needed to identify possible damage in a short-circuit test transformer, during experiments for modeling secondary electrical arcs. In some cases the arc had self-extinguished applying a steep wave to the test circuit and its ac source (transformer). Aiming to investigate if there was any interaction between the suspect transformer and testing circuit and its excitations, a research was conducted in laboratory with controlled atmospheric impulse chopped waves, with typical “fall times” for discharges in air. An analysis considering the components of frequency generated by chopped in air, the amplifier factors generated by test circuit (short line + auxiliary transformer), the natural resonance frequencies of the suspect transformer and its frequency components of the BIL showed interesting coincidences that can be extrapolated to real power system conditions.