Abstract: An integrated self-firing thyristor structure which comprises a main thyristor having a first emitter portion, a main base, a first inhibition base provided with a bore, a second emitter portion, an auxiliary thyristor using said first emitter portion and said main base and having a second inhibition base which extends in said bore and is insulated therefrom, and a third emitter portion, a conductive element connecting said first inhibition base to said third emitter portion and switching means connected between said conductive element, said second emitter portion and said second inhibition base so that the self-switching-on function of the integrated thyristor can be inhibited by said switching means.

Abstract: An a-c current sensor for measuring the current which flows in a conductor has an insulating frame having a central compartment open at its upper end and encompassed by a U-shaped receptacle for a bent portion of the conductor. A coil is housed in the central compartment. The frame is slidingly mounted within a sleeve made of a soft magnetic material and having two assembled half-shells. The voltage generated by the current across the coil is proportional to the intensity of current flow.

Abstract: A protection device has first and second differential transformers each with a toroidal magnetic core through which pass the neutral and phase conductors of an alternating current distribution network, and a secondary winding. The secondary winding of the first transformer is coupled to the input of an amplifier followed by a rectifier, a threshold comparator and a control device adapted to release a circuit-breaker. The secondary winding of the second transformer is coupled to the output of the amplifier. The improvement is constituted by an auxiliary amplifier inserted between the output of the first amplifier and the terminals of the secondary winding of the second differential transformer.