| 摘要 |
PURPOSE:To obtain a protective differential relay device improved in sensitivity by equipping the device with the first switching circuit switching impedance of a differential circuit, second switching circuit switching the impedance to a different one, a plurality of voltage detection elements detecting terminal voltage and a breaker trip interlock circuit. CONSTITUTION:A voltage detection element 33 detects voltage, transformed by a transformer 26, and transmits a signal when a primary current obtains a proper value. A voltage detection element 32 detects voltage in a high value and generates a signal. The voltage detection element 33 detects a level of the voltage, operating when a secondary current is in not less than a predetermined value and forming an adequate output circuit in the outside. A transformer 21, ignition circuits 21-1, 22-2 and semiconductor power switches 23-1, 23-2 form the first switching circuit 41, and a transformer 27, ignition circuits 28-1, 28-2 and semiconductor power switches 29-1, 29-2 form the second switching circuit 42. An on-off output signal, obtained by the use of detection elements 30, 31, 32, 33, form a breaker trip interlock circuit. |
