| 摘要 |
PURPOSE:To obtain a steady detecting sensitivity irrespective of the magnitude of a current, by a method wherein a circuit is disconnected through detection of a phenomenon in which a primary current of a test transformer, applying a voltage to an object to be tested, is rather delayed in phase after the insulation breakdown current than before the insulation breakdown. CONSTITUTION:With a disconnecting switch 7 closed, a compensation reactor 6 is actuated to relieve a load of a voltage regulator 2, and if a difference between the primary and the secondary phase of the voltage regulator 2 is approximately zero, an inverse power relay 10 advances to detect a reactive power corresponding to a current. In this case, it is judged that no insulation breakdown occurs to an object A to be tested. If the insulation breakdown occurs to the object A to be tested due to the increase in an applying voltage, a primary current of a test transformer 3 rapidly changes into a delay current in which an internal reactance produces a load. As a result, torques, being entirely contrary such that are exerted from an advance reactive power to a delay reactive power, are applied to the inverse power relay 10 to generate a detection signal to disconnect a circuit through the operation of a breaker 1. |
