Improvements in and relating to electrical protective relays and relay systems

摘要

899,941. Protective arrangements. ENGLISH ELECTRIC CO. Ltd. July 15, 1958 [July 15, 1957], No. 22295/57. Class 38 (5). In a distance relay arrangement having operating, restraining and polarizing circuits, means responsive to a predetermined fault condition are operative to switch a transformer circuit coupled between the polarizing circuit and the voltage transforming means supplying this circuit to step up the voltage supplied to the polarizing circuit on the occurrence of the predetermined fault condition, e.g. to prevent loss of polarizing voltage in the event of a fault near the relay arrangement. In the arrangement shown, a fault detector relay has operating windings OFDA . . . OFDC, restraining windings RFDA ... RDFC and polarizing windings PFDA . . . PFDC. When this detector relay is suitably energized, it changes over contacts SA . . . SC to change the connection of auxiliary current transformers TA . . . TC supplying operating windings OA . . . OC of the main distance relay from delta to star, and at contacts SASP1/SP ... SCSP1/SP changes the connections of restraining windings RA . . . RC and polarizing windings PA . . . PC of the main relay from delta to star. At the same time the detector relay changes over contacts SSP1/SPASP1/SP. . . SSP1/SPCSP1/SP to connect auto-transformers ATA ... ATC in circuit with the main relay polarizing windings PA . . . PC to increase the polarizing voltage.