| 摘要 |
<p>PURPOSE:To accurately detect the voltage-applied state of an isolator by a method wherein voltage-application-side electrodes are installed on both sides of the isolator, a voltage to ground of the voltage-application-side electrodes is divided to an intermediate electrode and a voltage across the voltageapplication-side electrodes and the intermediate electrode is taken out as a light modulation signal by means of an optical voltage sensor. CONSTITUTION:An insulator 5 with a built-in optical fiber is arranged between a vertical bus terminal insulator 2 on a stand 1 and an isolator 4. An optical PT 8 is attached to the head part of the insulator 5; a voltage-application-side electrode 12 and an intermediate electrode are installed at the inside of the optical PT 8. The intermediate electrode is connected to an optical voltage sensor via an electrode for sensor-voltage application use; a divided voltage between the voltage-application-side electrode 12 and the intermediate electrode is converted into a light modulation signal; it is transmitted to a photodetector 30 at a voltage- detection-apparatus board via an optical fiber; it is converted into an electric signal. The electric signal is compared with a reference voltage level by means of a judgment device 31; it is judged whether the electric signal exceeds a reference voltage or not. An optical PT 8 on the opposite side is judged in the same manner. When it is judged that the optical PT 8 at least on one side is at a reference level or lower, the operating permission signal of the isolator 4 is output from an input relay circuit unit 32.</p> |
