| 摘要 |
<p>PURPOSE:To enable accurate measurement of a current ranging from a small current to a large one without enlargement of a gap distance by winding a closed-loop-shaped coil on a core so as to cancel a magnetic flux due to a through conductor. CONSTITUTION:A photosensor 2 is inserted inside a gap of a core 1 and a current flowing through a through conductor 3 is thereby caught as a change in a magnetic field and measured. On the occasion, a loop-shaped coil 4 is wound round on the outer periphery of the core 1. The magnetic field generated by the current flowing through the conductor 3 generates a magnetic flux in the same direction, and concurrently such a secondary current as to cancel the magnetic flux flows through the coil 4. When a coefficient of coupling is 100% on the occasion, the magnetic field is canceled and dose not occur. However, it is lower than this rate inevitably due to a leakage flux and others and the magnetic flux due to the difference occurs. By detecting this magnetic flux, saturation of the core is prevented without enlargement of a gap distance, deterioration of characteristics due to the effect of another magnetic field and others is avoided, and the current ranging from a small current to a large one can be measured.</p> |
