Patent ID: 6674278
Filing Date: 2004-01-06
Classification: G01R

Abstract:
An alternating current detector comprising:a current transformer having a primary winding through which a current to be detected flows, and a secondary winding and an auxiliary winding, magnetically coupled to said primary winding via a core, one end of each of said primary, secondary and auxiliary windings being connected to each other and thus form a common terminal; an operational amplifier for amplifying a voltage induced in said auxiliary winding, and applying the voltage to said secondary winding to pass a current through said secondary winding, said current having such a polarity as to restrain a change in magnetic flux of said core; and a current data reading system for reading the voltage corresponding to the current to be detected, wherein a reference potential of said operational amplifier is set as an intermediate potential of a voltage of a power source of said current data reading system, whereby a voltage corresponding to the current to be detected is induced in said secondary winding.