Set of electrical protection devices with two levels that are connected in series

A set of electrical protection devices with two levels that are connected in series, the first level including a circuit breaker that is a first or upstream circuit breaker and the second level including one or more circuit breakers that are a second or downstream circuit breakers, which are connected in parallel with respect to one another, the one or more downstream circuit breakers having a lower rating than the first circuit breaker, each circuit breaker including, for each of the phases, a switching block through which passes a current line on which two separable contacts and a sensor for measuring the current are placed, means for actuating the contacts manually or by remote control, means for automatically opening the contacts controlled by a trip, said trip being controlled by the current sensor, and including means for adjusting the long-delay trip curve for inverse time and the short-delay trip curve with a no-trip time, the trip of the one or more second circuit breakers further including instantaneous protection means allowing the trip associated with the one or more second circuit breakers to be actuated when the current reaches an instantaneous trip DIN threshold of the one or more second circuit breakers, wherein the trip for the upstream circuit breaker, instead of including instantaneous protection means, includes, firstly, a first trip chain making it possible to adjust the long-delay trip curve for inverse time and the short-delay trip curve with a no-trip time and, secondly, a second trip chain including an optical sensor that is capable of discerning light between 300 and 450 nm by eliminating visible and infrared light so as to eliminate the light that is characteristic of gas jets emitted by the one or more downstream circuit breakers during a switching operation, and means for simultaneously measuring the current level and the maximum threshold of light emitted at the busbars, the second trip chain being capable of causing the upstream circuit breaker to trip when the current exceeds a predetermined value and the light emitted exceeds a predetermined threshold for emitted light.