NEUTRAL-POINT GROUND-FAULT DETECTION AND PROTECTION UNIT

摘要

PURPOSE: To make it possible to cut off only a fault section when a ground fault takes place in a bus line, by connecting a current transformer to each neutral point of a transformer, and using a selective-breaking protective relay put in series in an annular circuit and connected to a transformer on a secondary side and a ground-fault detecting common relay, in which a small annular circuit is constituted. ;CONSTITUTION: A current transformer 6 is connected to each neutral point of a transformer 1. A plurality of selective breaking protective relays 31 and 32 are connected to the transformer 1 on a secondary side to protect an overall circuit. The protective relays 31 and 32 are connected in series annularly in an annular current circuit to carry a ground-fault current or an unbalanced current. In addition, a ground-fault detecting common relay 10 is connected to the annular current circuit 7 in a way that each annular circuit for the protective relays 31 and 32 are separately formed. As a result, when a fault in bus line takes place, only a power-supply circuit related to a defective bank can be cut off, and in this way, reliability in ground-fault protective system can be improved.;COPYRIGHT: (C)1996,JPO