Abstract: A current detection circuit and a transformer current measurement system are offered, in which when elements and circuit, which cannot operate originally unless a transformer with small excitation inductance is used, are connected to a primary side of the transformer, even if the transformer, whose excitation inductance is large, is used, transformer current (primary current and secondary current) can be measured without deteriorating operations of the elements and circuit. [Means for solving] A current detector CT (current transformer) is in series connected to a primary winding 111 of a transformer 11, and an inductor La is in parallel connected to to a series connection of the current detector CT and the primary winding 111. And, secondary current I2 of the transformer 11 is measured based on a value of primary current IT detected by the current detector CT.

Abstract: A current detection circuit and a transformer current measurement system are offered, in which when elements and circuit, which cannot operate originally unless a transformer with small excitation inductance is used, are connected to a primary side of the transformer, even if the transformer, whose excitation inductance is large, is used, transformer current (primary current and secondary current) can be measured without deteriorating operations of the elements and circuit. [Means for solving] A current detector CT (current transformer) is in series connected to a primary winding 111 of a transformer 11, and an inductor La is in parallel connected to to a series connection of the current detector CT and the primary winding 111. And, secondary current I2 of the transformer 11 is measured based on a value of primary current IT detected by the current detector CT.