| 摘要 |
<p>PURPOSE:To prevent generation of measuring errors under influence of an external magnetic field by a method wherein an iron core adapted to form a magnetic path interlinking with a primary conductor is used in an ammeter and the core concentrates a magnetic flux due to the primary conductor to preclude the generation of an induced voltage by an external magnetic field which prevents the generation of measuring errors affected by the external magnetic field. CONSTITUTION:A magnetic path is formed with an iron core 4 interlinking with a primary conductor 1 of an ammeter and the core 4 is wound with a first winding 5 to short-circuit the winding 5. The core 4 is further wound with a second winding 6 and a measuring section (not illustrated) is connected to both terminals of the winding 6. Then, as a primary current flows through a primary conductor 1, a secondary current flows through the winding 5 and an electromotive force is generated in the winding 5 to cancel a magnetic flux generated in the core 4 by the primary conductor 1 so that the magnetic flux generated in the core 4 is reduced. A voltage corresponding to a secondary voltage is generated in the secondary winding 6 by the magnetic flux with the core 4.</p> |
