GB196785A - Improvements in automatic air and oil break electric switches - Google Patents

Abstract

196,785. Ferguson Failin, Ltd., and Pailin, G. March 31, 1922. Automatic circuit-breakers &c.-Relates to air- and oil-break switches for polyphase circuits in which a switch for each phase is tripped either by an overload magnet or by hand or by the tripping of the switch in one of the other phases. A switch arm for each phase is mounted on but insulated from an earthed rotatable base and is held closed by a catch which can be raised either by a trip coil or by the mechanical rotation of the base. Fig. 1 shows the invention applied to a three-phase circuit, Fig. 2 shows more in detail one of the switches and Fig. 4 shows diagrammatically its tripping mechanism. Each switch comprises a switch arm a pivoted at b to a rotatable base c and the bases c are connected by links 7 so as to rotate together. Each base c is mounted by means of insulators d, e to the earthed base f, which can be rotated by a handle. A bracket t, fixed to the base c loosely embraces the switch arm a so as to permit a small relative rotation between the arm a and the base c, and a lever u pivoted to the arm a also passes through a hole in the. bracket t. When the switch arm a is moved counter-clockwise into contact with the fixed contact h. a pin n<1> on the arm a engages a forked lever np which moves clockwise till held by a catch q. The fork on the lever np then retains the arm a in position till the catch q is raised. This is effected either by the electromagnet s or mechanically by turning the base c, the bracket t on which then engages the lever u which in turn engages a lever vw which lifts the catch. The breaking movement of the switch arm a is then accelerated by arcing horns i, j, and mechanical means (not shown). Instead of one switch arm a in each phase there may be several. Fig. 10 shows four arms con. nected in series and mounted on one base. An overload coil (not shown may release one of the arms a and the consequent rotation of the base releases the other arms. The tripping of one switch and the consequent rotation of its base causes simultaneous rotation of the bases associated with the other phases, which in turn effects the tripping of the other switches.