Patent ID: 8797020

Claim:
Electrical current sensor comprising a measuring circuit and an inductor for measuring a primary current I p flowing in a primary conductor over a current range from a minimum specified current amplitude to a maximum specified current amplitude, the inductor comprising a saturable magnetic core made of a highly permeable magnetic material and a secondary coil for carrying an alternating excitation i configured to alternatingly saturate the magnetic core, said secondary coil being connected to the measuring circuit, wherein the measuring circuit is configured to supply a positive or negative voltage to the inductor, to switch off said positive or negative voltage when a condition signalling saturation is reached, to measure a time to saturation t 1 in one direction and a time to saturation t 2 in another direction of the magnetic core and determine therefrom a value of the primary current for primary currents having an amplitude in a first portion of the current range from the minimum specified current to a transition amplitude, the measuring circuit being further configured for evaluating an average value of said alternating excitation current i during phases when a voltage is supplied to the inductor and before the saturation condition is reached, and determining therefrom a value of the primary current for primary currents having an amplitude in a second portion of the current range from the transition amplitude to the maximum specified current amplitude.