PCM electric current differential protection relay

摘要

The invention discloses a PCM current differential protection relay, equipped with a mechanism which can detect the situation and control without misoperation under the condition that even the relay can not identify the switch and the transmission relay time of the duplex transmission line switch changes sharply. A resetting processing part (20), according to the judgment of the establishment of three conditions that a current change detecting part (17) shows no change of a home terminal current data, a difference current detecting part (19) detects a difference current exceeding a adjustment value and a phase different detecting part (18) determines that the home terminal current data of the present time and a period before is out of step, provides operation instruction to a synchronous processing part (14) and a ratio differential operation part (15). The synchronous processing part (14) receives the operation instruction and resets the time synchronization of the home terminal current data, and the ratio differential operation part (15) terminates the operation processing, stores and outputs the operation results in the period before obtaining accurate synchronization.