| 摘要 |
PURPOSE:To accomplish accurate locking of malfunctioning of a differential relay through accurate detection of any folding in a wireless machine which was previously unable to be detected with a normal noise detector by transmitting pilot signals varied from each other to one terminal from the other which are both adapted to mutually transmit signals. CONSTITUTION:A pilot signal generator 3A and a pilot signal generator 3B transmit signals from one terminal to the other in such a manner that the signal of the former generator is set at a given level while the signal of the latter generator at a zero level. Normally, an abnormalty detector 10A provided at a terminal A detects the zero level. In case of a folding in a wireless machine, the signal transmitted by the terminal of one generator is identified the same as the signal received. At this mement, a pilot signal of a given level is inputted to the detector 10A. With such an arrangement, the detector 10A discriminates the level of signals, and thus, depending on the level of the signals, it can be determined whether the generator works normal -- when it is at a given level -- or the folding of the wireless machine takes place -- when it is above this level. Thus, malfunctioning of the differential relay 9A can be locked accurately. |
