| 摘要 |
PURPOSE:To reclose a relay reliably with no failure by performing high speed polyphase reclosing if zero-phase current, led out from current information at this end or counterpart end in each set, is higher than a predetermined value at the time of abnormality of a parallel multi-wire transmission line. CONSTITUTION:Differential relays 24, 25 are provided at the opposite ends of two sets of three-phase transmission lines 36, 37 constituting a protective object, i.e., parallel multi-lines (two lines on the drawing), and current information is communicated on a line 35 between signal transmitters 26, 27. Upon occurrence of a fault in a protective section, any one of trip outputs 59-61 of each phase produces a logical 1, and thereby an OR circuit 62 outputs a logical 1. In the case of a ground fault, one of ground current relays 63, 1.1 employing a current 3I0 at this end or counterpart end goes logical 1 without fail and an AND circuit 64 is established through an OR circuit 10 to produce a logical 1 for commanding high speed reclosing. In the case of short circuit fault, the OR circuit 62 outputs a logical '0'. According to the system, high speed reclosing is prevented easily from failure and carried out reliably. |
