Device for the reading of direct and/or alternating currents

摘要

The present invention is related to a device ( 1 ) for the detection of direct and/or alternating current to be used in the realisation of highly sensitive amperometric measuring instruments or for the detection of differential faults along with automatic switches. The inventive device comprises a magnetic core ( 5 ) disposed in such a manner to surround at least one current-carrying conductor ( 6 ). A winding ( 10 ) surrounds the magnetic core ( 5 ) and is electrically connected to an electrical resistance ( 60 ). A voltage source ( 40 ) generates a drive voltage (Vexcit) which permits the circulation of a pick-up current (Iexcit) in the said winding ( 10 ) and in the said core ( 5 ). Amplification means ( 20 ) are used to detect the voltage (Vsense) at the terminals of the resistance ( 60 ) in order to generate a first signal (Vamp 1 ) which is representative of the above defined current (Iexcit). The inventive device ( 1 ) also comprises a feedback adjustment circuit block ( 70 ) which acquires the first input signal (Vamp 1 ) in order to generate a second signal which inverts the said drive voltage (Vexcit) when the pick-up current (Iexcit) reaches preset values.