Abstract: In a method of control of a protection system which is applicable in particular to the initiation of emergency shutdown of a nuclear reactor, N measurements of one or a number of physical parameters are taken and processed by N matching and/or computation units, the median of the N signals corresponding to the N measurements is selected. The signals are obtained at the output of the matching units and the median is compared with a reference value in order to initiate protective action.

Abstract: In a nuclear reactor protection system, the control device initiates reactor shutdown when the amplitude of a voltage signal delivered by a detector oversteps a range limited by two adjustable values. The device comprises a stabilized supply, a detector supplied by a rectifier for delivering a d.c. voltage having an amplitude Ve which is proportional to the value of the signal to be measured, two generators for producing d.c. voltages of opposite sign having amplitudes Vd and Vref, and an adjustable voltage divider which delivers a periodic rectangular-wave voltage having an amplitude Vs. The detector output voltage is compared with the algebraic sum of the values Vd, Vref and Vs by means which produce a voltage level of 0 if the amplitude Ve is outside the range (Vd + Vref, Vd + Vref + Vs) and a voltage level of +1 if the amplitude Ve is within said range.

Abstract: An electronic unit for controlling the safety absorbers of a nuclear reactor comprises a self-supplied AND.sub.1 circuit for performing logical multiplication of input signals each capable of assuming one out of two values, series-connected modules each constituted by a dc/ac converter, the output of the last module being coupled to the first converter and to a regulator input at which is obtained a logical a.c. signal whose value corresponds to the result of multiplication of the different input signals, a static intensity regulator with negative current feedback for modulating the width of the square waves delivered by an isolation transformer, a rectifier for delivering a constant current to a load impedance.