Differential protection device allowing the detection of leakage or fault currents in an electrical installation that is supplied with power either by at least two phase conductors of a network (2, 2', 2'') or by at least one phase conductor of a network (2, 2', 2'') and by a neutral conductor of said network, said device comprising at least one detection and control module that is functionally active or operational for frequencies of the fault signal from 0 Hz to a few tens of Hz, this module being supplied with power by the network, this module comprising, on the one hand, a measurement torus made of a ferromagnetic material that the aforementioned conductors (2, 2', 2'', N) pass through, on the other hand, an excitation circuit for exciting the torus comprising a generator of AC signals that produces a periodic carrier and, finally, a measurement winding that is able and intended to generate a fault signal resulting from the appearance of a differential fault in the network, said measurement winding being connected to circuits (7, 8, 9, 10) for processing and evaluating the fault signal and for transmitting a control signal to a breaking or opening means also forming part of the differential protection device, the aforementioned circuits (7 to 10) forming the components of an operational electronic chain belonging to the detection and control module, which device is characterized in that the circuits (7 to 10) of said operational chain comprise at least, on the one hand, a circuit that delivers a signal (SVMR) corresponding to the rectified average value of the fault signal, or a derived signal (SD') that is directly dependent on said fault signal, and, on the other hand, a comparator circuit that compares said rectified average signal (SVMR) with a predetermined or preset threshold value and that conditionally or selectively delivers a control signal for controlling the breaking or opening means, depending on the result of said comparison. said device comprising at least one detection and control module that is functionally active or operational for frequencies of the fault signal from 0 Hz to a few tens of Hz, this module being supplied with power by the network, this module comprising, on the one hand, a measurement torus made of a ferromagnetic material that the aforementioned conductors (2, 2', 2'', N) pass through, on the other hand, an excitation circuit for exciting the torus comprising a generator of AC signals that produces a periodic carrier and, finally, a measurement winding that is able and intended to generate a fault signal resulting from the appearance of a differential fault in the network, said measurement winding being connected to circuits (7, 8, 9, 10) for processing and evaluating the fault signal and for transmitting a control signal to a breaking or opening means also forming part of the differential protection device, the aforementioned circuits (7 to 10) forming the components of an operational electronic chain belonging to the detection and control module, which device is characterized in that the circuits (7 to 10) of said operational chain comprise at least, on the one hand, a circuit that delivers a signal (SVMR) corresponding to the rectified average value of the fault signal, or a derived signal (SD') that is directly dependent on said fault signal, and, on the other hand, a comparator circuit that compares said rectified average signal (SVMR) with a predetermined or preset threshold value and that conditionally or selectively delivers a control signal for controlling the breaking or opening means, depending on the result of said comparison.