| 摘要 |
<p>Logic circuitry for a directional comparison blocking protective relay scheme is described. A forward-reaching and a reverse-reaching protective relay (38) located at the local and remote terminals of a protected line segment (43) determine whether a fault is internal or external to the protected line segment. To carry out this function, the protective relays produce signals (64, 70, 68, 62) representative of fault location and communicate with each other via a communications channel (65). Processing the signals at each terminal is performed to determine the fault location and avoid tripping when the fault character changes. By using fault detectors to determine the existence of a fault, the logic at each terminal for combining the signals is simplified and security against false tripping is improved.</p> |
