| 摘要 |
<p>PURPOSE:To obtain a compact current transformer and to measure an accurate zero-phase current by connecting tertiary coils of respective phases in series, and providing a voltage sensor between both terminals of the series circuit and detecting a voltage proportional to the zero-phase current. CONSTITUTION:If one phase of a power transmission line is grounded and the zero-phase current flows to the opening/closing electrode 7a of a switch 7, a secondary current and a secondary voltage are generated at the secondary coil 8b of the current transformer 8 provided to the opening/closing electrode 7a, the same secondary voltage is applied to the secondary coils 9b and 10b of current transformers 9 and 10 provided to other opening/closing electrodes 7b and 7c, and detection voltages are induced at the tertiary coils 8c-10c of the current transformers 8-10. The tertiary coils 8c-10c of those current transformers 8-10 are connected in series, so the detection voltages are summed up and applied to the electrode of an optical voltage sensor 12. Consequently, light transmitted through the sensor 12 is polarized and a light signal polarized by an optical receiver 4 is sent from an optical reception path 3 and outputted to a display device 6 through a signal processing circuit 5.</p> |
