PURPOSE: To make it possible to detect a current flowing through an object to be measured accurately by providing coils in divided magnetic cores, connecting the coils so as to offset the effects of external magnetic fields, constituting an electric circuit, and detecting the current flowing through said circuit.
CONSTITUTION: A current I is made to flow through an object to be measured which is provided so as to traverse the hollow part of divided CT cores 20. Then a magnetic field H is induced in a closed magnetic circuit comprising divided magnetic cores 20a and 20b. Electromotive forces corresponding to the magnetic field H are generated in coils 11a and 11b. Since the electromotive forces are imparted in the closed electric circuit in the same direction, a current is generated through a resistor R. Thus a voltage is generated across the resistor R and measured with a voltmeter 30. The current I can be monitored in the form of the voltage. At this time, even if external magnetic fields H' pass through the coils 11a and 11b, the electromotive forces are formed in the reverse directions in the closed electric circuit and offset. Therefore current is not generated. In comparison with the case wherein one coil is used, the current can be detected at the sensitivity as high as twice. A minute current which is generated at a part where an external magnetic field is intense such as leaking currents from insulators and the like can be detected accurately.
UEYAMA YUJI
KAWAMURA TAKESHI
KONDO TAKU
