GB336452A - Improvements in or relating to high-potential air-break electric switches - Google Patents

Abstract

336,452. Koch & Sterzel Akt.-Ges. Nov. 7, 1928, [Convention date]. Transformers.- High-potential air-break switches for use on overhead conductor systems have at least one of the insulators carrying the switch parts formed to contain a graduated measuring transformer. As shown in the Figure the switch has two fixed contacts mounted on fixed insulators 13, 14 between which is disposed as third insulator 15 rotatable on a ball race 12 and carrying a switch arm 11 terminating at its end in contact-members 16, 18 adapted to engage the fixed contacts. The insulators are built up of sections and are surrounded by metal bands at each joint between sections each section carrying one stage of a transformer or choking coil. Thus the fixed insulator 13 carries the stages 24 - - 27 of a graduated potential transformer supplying a voltmeter V and the insulator 14 the stages 28 - - 31 of a graduated earthed choking coil. The stages 19 - - 21 of a graduated current transformer are contained in the central rotatable insulator 15 the first stage being connected in series with the arm 11 and the final stage passing over through flexible leads 23 to a currentmeasuring instrument A. When the switch is open this transformer is isolated from the supply so that it may be inspected or repaired. A shunt resistance 17 may be provided as shown to allow the passage of current surges provided in the current transformer. In alternative forms of switch a single-switch blade may be used and the switch blade or blades may be mounted for movement on fixed insulators. The heating of the transformers or chokes, especially in cases where oil-filled insulators are employed, is stated to prevent freezing together of the switch contacts.