| 摘要 |
PURPOSE:To obtain a small-sized, light-weight and low-costing tap switching apparatus not requiring provision of transformers, by detecting a voltage across a nonlinear resistance element by means of an light-emitting element and transmitting the optical signal by means of an optical fiber. CONSTITUTION:A first voltage detecting device 41 provided by a light-emitting element is connected in parallel to the parallel connection between a first semiconductor switch 11 and a first nonlinear resistance 19. A second voltage detecting device 42 provided by a light-emitting element is connected in parallel to the parallel connection between a second semiconductor switch 12 and a second nonlinear resistance 20. When the semiconductor switch is opened, the voltage applied to the nonlinear resistance element connected to the subject switch is increased, and the voltage detecting device associated therewith detects the increase in voltage and emits an optical signal. The optical signal is transmitted through an optical fiber. Accordingly, if electric current exceeding a minimal time conduction flows through the nonlinear resistance element, the on-load tap switching apparatus takes proper measures such as locking the next tap switching operation or giving an alarm.
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