Abstract: An electronic trip device for a circuit breaker comprising at least one current sensor supplying a current to a first power supply circuit. A distribution line connected to an output of the first power supply circuit distributes an electrical voltage regulated by a first chopping regulator to electronic circuits of the trip device. The trip device comprises a second power supply circuit connected to an external power source and a second chopping regulator connected between the second power supply circuit and the distribution line. The second chopping regulator operates in synchronized manner with the first chopping regulator.

Abstract: The terminals of a test circuit are directly connected to outputs of the transformer secondary windings and to the input of the rectifying circuit so that the test current checks operation of the trip device. A sign detection circuit supplies a processing circuit with the values of the polarities of the rectified currents. The processing circuit comprises means for determining the presence of a test current when the sign of the rectified current comprising the test current remains continuously in the same polarity. A differentiation of the continuous polarity, positive or negative, of the test current enables testing to be carried out with or without earth protection tripping.

Abstract: An electronic trip device comprising, for each phase or neutral line, a rectifier bridge formed by four diodes which rectify the transformer current, a resistance for measuring the rectified current, and a circuit for detecting the sign or polarity of the measured current connected to one end of the transformer. A processing circuit calculates a value representative of the earth fault current by adding all the current values whose corresponding sign is positive and subtracting all the current values whose corresponding sign is negative. This current value is processed so as to bring about tripping when a threshold is exceeded for a preset time.