Patent ID: 8421475

Claim:
An AC current sensor ( 22 ; 24 ; 26 ) for performing a substantially real time measurement of electric AC current magnitude in a conductor and for generating a non-electrical wave signal as an output, said non-electrical wave signal comprising a series of pulses having a frequency, which is proportional to the magnitude of current measured, said current sensor comprising: a current responsive unit comprising an inductive wire-wound current transformer ( 2210 ), adapted for mounting adjacent to said electric conductor, said inductive wire-wound current transformer ( 2210 ) providing electrical power as a driving current for said current sensor; a sensor circuitry ( 2220 ) comprising current level indication circuitry ( 2222 ) comprising a current-to-frequency converter adapted to provide said non-electrical wave signal as a substantially real time current level indication pulse signal (CS 1 ) having a pulse width of 0.5 to 5 μs and a pulse frequency (Pf cs ) that is proportional to the magnitude of said conductor current when it is within a predetermined current interval (I 1 -I 2 ); and said sensor circuitry ( 2220 ) further comprising a means ( 2230 ) for emitting said non-electrical wave signal as an output to a remote detector, said means ( 2230 ) further being adapted for providing at least one further non-electrical wave indication signal in form of a current polarity indication signal (POS) to the remote detector, wherein said non-electrical wave signal and at least one further non-electrical wave indication signal are provided simultaneously.