Electrical inductance as an electrical passive attenuator, with - an iron core composed of sheets (4a, b) insulated from one another to form a stack of sheets as a magnetic flux conducting body with - three longitudinal legs (1a, 1b, 1a) arranged in parallel at a distance from one another and extending in the direction of extension, with one end on each side, forming interior spaces, - two yokes, each yoke connecting the ends of the longitudinal legs (1a, b) pointing to the same side to form at least one air gap, - the yokes consist of metal sheets (4a, b) which are bent into a C-shape and fit exactly into one another, - three circularly closed circumferential coils, each of which is a perfect fit around one of the longitudinal legs (1a, b), wherein - each yoke has projections (7a, b) strutting in the direction of extension of the longitudinal legs (1a, 1b, 1a) at both ends of the yoke, - an outer longitudinal leg is arranged between each two mutually directed extensions (7a, b) of the two yokes, forming at least one air gap, - the yokes are braced against each other by means of a clamping device suitable for pressing the yokes against each other so that pressure is built up and maintained on the spacers defining the air gaps, the parts (6a, b) of which are arranged outside the sheet metal package, - the iron core, apart from the two inner spaces between the longitudinal legs (1a, b), is free of perforations, - between all the longitudinal legs and the inner wall of the coil are arranged, which are longer than the length of the central longitudinal leg and extend on both sides into the region of the yokes. - an iron core composed of sheets (4a, b) insulated from one another to form a stack of sheets as a magnetic flux conducting body with - three longitudinal legs (1a, 1b, 1a) arranged in parallel at a distance from one another and extending in the direction of extension, with one end on each side, forming interior spaces, - two yokes, each yoke connecting the ends of the longitudinal legs (1a, b) pointing to the same side to form at least one air gap, - the yokes consist of metal sheets (4a, b) which are bent into a C-shape and fit exactly into one another, - three longitudinal legs (1a, 1b, 1a) arranged in parallel at a distance from one another and extending in the direction of extension, with one end on each side, forming interior spaces, - two yokes, each yoke connecting the ends of the longitudinal legs (1a, b) pointing to the same side to form at least one air gap, - the yokes consist of metal sheets (4a, b) which are bent into a C-shape and fit exactly into one another, - three circularly closed circumferential coils, each of which is a perfect fit around one of the longitudinal legs (1a, b), wherein - each yoke has projections (7a, b) strutting in the direction of extension of the longitudinal legs (1a, 1b, 1a) at both ends of the yoke, - an outer longitudinal leg is arranged between each two mutually directed extensions (7a, b) of the two yokes, forming at least one air gap, - the yokes are braced against each other by means of a clamping device suitable for pressing the yokes against each other so that pressure is built up and maintained on the spacers defining the air gaps, the parts (6a, b) of which are arranged outside the sheet metal package, - the iron core, apart from the two inner spaces between the longitudinal legs (1a, b), is free of perforations, - between all the longitudinal legs and the inner wall of the coil are arranged, which are longer than the length of the central longitudinal leg and extend on both sides into the region of the yokes.