GB1008744A - A diverter switch for a transformer tap changer - Google Patents

Abstract

1,008,744. Regulating switches; oil break and oil blast switches. SOC. NAGIONALE DELLE OFFICINE DI SAVIGLIANO. Oct. 31, 1963 [May 25, 1963], No. 43114/63. Heading H2B. A three-phase diverter switch for a transformer tap-changer has a carriage 4 movable between end positions by a shaft 1 with cam track 2a and pin 6 and moving with snap action a spider 8 carrying three main and three auxilliary moving contacts 26, 13 between pairs of corresponding fixed main contacts 11, 11a of the spring plunger type and rigid fixed auxiliary contacts 29, 29a, the contacts 13 being extensible to permit their making with both sets of fixed auxiliary contacts during part of the travel of spider 8. Rotation of shaft 1 180 degrees in either direction drives the carriage 4 by means of the cam track 2a and follower 6 from one end to the other of a housing 17; near the end of its travel in either direction projections 19 on the carriage trip toggle linkages 14 14<SP>1</SP> allowing springs 9, 9a to drive the spider 8 from one position to the other. Initially connection is established to first tappings of the transformer windings through contacts 26, 11a; during the first movement of spider 8 contacts 26, 11a break but connection is maintained through impedances (not shown) between contacts 11a, 29a; thereafter contact 13 makes with 29 establishing connection to second taps through further impedances between contacts 11, 29; contacts 29a, 13 then break and finally contacts 26, 11 make a direct connection to the second taps. The contacts 13 consist of two plungers 13, 13a biased apart in a support 31 on the spider 8. The plungers 13, 13a are hollow and during the initial movement oil, in which the switch is immersed, is drawn into them and during the last movement is driven out to blow out the arc formed between contacts 13, 29a. The support 31 is inclined to the shaft 1 causing a degree of sliding between contacts 13, 29, 29a to clean them.