Abstract: A cylindrical step selector for stepped transformer has its contact rings supported by horizontal conductors which extend out of the insulated cylinder surrounding the shaft which can displace the contact bridge along such ring and into engagement with a fixed contact. Externally of the cylinder, the conductors are aligned one above the other so as to be engageable by a pair of clamping bars which provide additional bracing. The conductors may be turned upwardly along these bars and held to the latter by straps.

Abstract: A cylinder of electrically insulating material provided with a plurality of stationary contacts has a shaft rotatably disposed therein about an axis of the cylinder and is formed with movable contact members engageable with the contacts, and a bearing assembly in which the shaft is journaled on the cylinder at least at one end thereof, the bearing assembly including at least two tubes of electrically insulating material traversing the wall of the cylinder at opposite sides thereof so that opposite ends of the tubes project beyond the cylinder, the projecting ends of the tubes having slits formed therein, and a bearing member of electrically insulating material supported centrally and nonrotatably by the tubes and supporting the shaft for relative rotation of the shaft and the bearing member, and respective wedges received in the slits for spreading the split ends of the tubes to anchor the tubes at the wall of the cylinder.

Abstract: A step selector for a stepped transformer has an electrically insulating cylindrical wall provided with fixed contacts, e.g. at different levels and, for each contact level, a radial arm composed wholly of electrically insulating material is affixed to a cylindrical shaft rotatable about the axis of the cylinder and within the latter. The radial arm has a flange lying against the shaft and extending over substantially 120.degree. of an arc thereof. An inward projection on the flange engages a recess in the shaft and the flange is held against the shaft by at least one band of fibrous material impregnated with a self-hardening synthetic resin. The outer end of the arm carries a contact bridge slidable on a contact ring which nonrotatably surrounds the shaft and lies in the plane of the respective fixed contact which is engageable by the bridge.

Abstract: A multiphase under load transfer switch of the Jansen-type for tapped regulating transformers. The main contacts and the switch-over contacts of the transfer switch are formed by vacuum switches. The vacuum switches are operated by a common drive mechanism for all of the vacuum switches of all three phases of the transfer switch. The required sequence of the operation of the vacuum switches is achieved by interposition of lost motion connection means between said common drive mechanism and pairs of aligned operating rods for pairs of superimposed vacuum switches. A special common drive mechanism for said pairs of aligned operating rods for operating pairs of superimposed vacuum switches includes a squirrel-cage-like system of helical compression springs which are loaded by pivotable cam means and operate, when subsequently expanding, said pairs of vacuum-switch-operating rods by the intermediary lost motion connection timing means.

Abstract: A transfer switch for load-tap changers of the Jansen-type is provided with a non-linear surge voltage protective resistor forming a shunt across two taps of a tapped transformer winding and arranged in such a way that a breakdown of the resistor does not result in a short-circuit across the section of the tapped winding situated between the two taps.