GB659360A - A high voltage isolating switch - Google Patents

Abstract

659,360. Air break switches. AKTIESELS KAPET PROTON, and MORCH, J. May 24 1949, No. 13872. [Class 38(v)] A high voltage isolator switch especially suitable for outdoor use has contacts. which cannot be easily iced-up and comprises a resilient contact blade 1 mounted with its greater width transverse to the swing- ing plane by means of a plate-spring hinge 5. The blade may be made of hard rolled copper or bronze and carry the current, but preferably the current is carried by a cable on the underside of the blade Fig. 2 (not shown) and the blade is of spring steel. The fixed contact 6 is of round-section copper bent into an open frame to provide a main contact 11 and spark contact 12, the contact 12 being higher than contact 11. The coacting surfaces of the contacts 1, 11, 12 may be coated with silver. The blade 1 is operated by an insulator 19 connected by an arm 20 to a crank 16 on a shaft 15 whereby when the latter is rotated clockwise by a chain 14 to close the switch, the blade 1 first engages the spark contact 12, and then on continued movement of the insulator 19 the blade is flexed, engaging the main contact 11 and leaving the spark contact 12. On opening the switch the blade again flexes and finally breaks circuit at the spark contact. This flexing also causes longitudinal movement of the blade contact-end whereby the coacting contact surfaces are kept clean, and the effect may be improved by making the blade concave on its contact-making side. The crank 16 rotates through slightly over 180 degrees between the open and closed positions and thus holds the switch locked. The blade 1 may carry a weight at its free end to act as a hammer in breaking the ice, and several switches may be mounted together and operated conjointly, in which case the shaft 15 may have a counterweight to balance the insulators 19. The fixed contact 6 may be mounted higher than the hinge 5 to hinder an arc being forced along the blade by a strong wind. In a modification, the blade is moved rectilinearly by compressed air to make a double-break.