| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an electric current sensor for easily detecting deterioration in insulators, etc. by detecting a magnetic field caused by an electric current flowing through the insulators, etc. while well eliminating the effect of internal/external noises. <P>SOLUTION: This sensor is put to use in the vicinity of a surface of an apparatus or equipment for detecting an electric current flowing in a surface of the apparatus or equipment. Two magnetic impedance effect elements 1ma and 1mb (m = 1 to n) are parallel disposed with their magnetism sensing directions made reverse to each other. Outputs of the respective effect elements are demodulated by demodulation circuits 3ma and 3mb (m = 1 to n). Demodulation outputs thereof are differentially amplified by arithmetic differential amplification circuits 40m (m = 1 to n) in sensor units Cm (m = 1 to n), with output ends thereof lumped together by an adder 50. The internal noises (noises that occur owing to temperature change, etc. in circuit elements such as diodes in an exciting power-supply circuit and the respective demodulation circuits) acting as in-phase inputs with respect to differential amplification can be canceled out. The external noises such as an earth magnetism component can be easily eliminated since the external noises hardly change with location and substantially do not change if the position of the electric current sensor is changed. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
