The purpose of this “Cahier Technique” is to set out the discrimination techniques which apply specifically to low voltage power circuit-breakers. These devices are characterized by their high rating (800 A to 6300 A), and their location at the head of the LV installation, generally directly downstream of an MV/LV transformer. This location justifies the strict discrimination requirements which apply to them. This article begins with a resumé ofdiscrimination techniques, followed by an explanation of the links between discrimination and general circuit-breaker characteristics. Finally, some practical examples will be provided on selection of devices to be installed.
