Abstract: A current sensor for measuring a time-varying electrical current (Im) in a portion of primary conductor (1), the sensor including a sensor conductor comprising first and second ends (3,4) for connection to a signal processing circuit, a first conductor portion extending from the first end and having a plurality of windings (5) to form a first coil portion, and a second conductor portion returning to the second end. Centres of the windings define a median coil place substantially parallel to the magnetic field (Hm) generated by the time-varying current (Im) to be measured, the sensor conductor defining one or a plurality of interference field surfaces as seen projected on a plane parallel to the median plane enclosed by clockwise or anti-clockwise interference field current circulating portions (22,23) of the sensor conductor.

Abstract: The current to be measured (I) passes in a conductor (1) enclosed with a Rogowski coil (4) and in the proximity thereof are arranged several magnetic field detectors (3). The sum of the signals from these detectors, formed in the device (2), and the signal supplied by the Rogowski coil are applied to a signal processor (7). The processor (7) comprises, for example, a first order delay device connected to the Rogowski coil output and means for amplifying/reducing the signals followed by adding means, the delay time constant and the amplifying/reducing factors being selected so that the device output (8) signal is proportional to the intensity of the current to be measured in a very wide frequency range, i.e. from 0 to more than 10 MHz.