| 摘要 |
<p>PURPOSE:To obtain a DC current sensor of high sensitivity which has a simple structure and an excellent detecting capacity even for a very small change of a current, in particular, in a DC leakage breaker or like and of which a hysteresis of the output characteristic is prevented. CONSTITUTION:In a construction wherein a detecting coil 3 is wound round in a toroidal shape on a ring-shaped detecting core 2 of a soft magnetic material through which a conductor 1 to be detected is disposed inside, and an exciting coil 5 is wound round in the toroidal shape on a ring-shaped exciting core 4 of the soft magnetic material which is connected to the detecting core 2 perpendicularly to the circumferential direction of the core 2, a modulating coil 43 is wound round and disposed on the detecting core 2 so that it passes through in the same direction as the conductor 1 to be detected. A part 6 of perpendicular intersection of the cores is saturated magnetically periodically by impressing an alternating current on the exciting coil 5, a magnetic flux generated in the detecting core 2 on the basis of a direct current I is modulated to make the detecting coil 3 output an electromotive force of a frequency being twice as high as the one of an exciting current and the direct current I is detected. Since a residual magnetic flux in the detecting core 2 is reduced by an alternating magnetic field generated in the modulating coil 43 on the occasion, a sensor thus constituted has an excellent detecting capacity even for a very small change in the current.</p> |
