Abstract: A tap-changing transformer system, utilized for voltage regulation of the line potential applied to a load from a source of energy, has a non-arcing switch to protect tap contacts during a tap change. A fail-safe circuit is utilized to determine that the non-arcing switch and its associated circuitry are operating properly before a movable tap contact is transferred from one stationary tap to another. In the event that the fail-safe circuit detects an improper operation of the non-arcing switch, the source is connected directly to the load to preclude the passage of any load current through the tap-changing transformer. A particular form of transfer switch useful in effecting the connection of the source directly to the load employs a current-limiting impedance arrangement.

Abstract: A device for transformation of alternating current-voltage which includes a core, a primary winding subassembly and a secondary winding subassembly. One or both of the primary and secondary winding subassemblies consists of at least one pair of equal turn and approximately equal resistance windings wrapped co-directionally around the core, and each having an equal number of tapped sections. A special tandem switch selectively interconnects tapped sections within winding pairs to provide a desired output terminal winding array such that all sections connected through the switch are energized, and are in the current carrying path at all selected switch positions, with selectively seriesed and selectively paralleled portions of the switch-coupled winding pairs being selectively encircuited at each switch position.

Abstract: A gear and boss protector for the spring driving mechanism of a tap selector such as a voltage regulator. A pair of hook cams form the protective means and they are mounted rotatably on the crank driven by the spring driving gear. One of the hook cams engages the driving boss on the driving gear should the gear reverse rotation in one direction, while the other hook cam engages the driving boss on the driving gear should the gear reverse rotation in the opposite direction. The engagement of the driving boss by the hook cam prevents the crank from being suddenly released causing damage to the gear or boss.

Abstract: Tap changer voltage regulating apparatus permits a tap changer selector contact to engage an open-circuited new tap without arcing and has a half-tap voltage auxiliary winding which permits halving the voltage being interrupted and doubling the number of steps and also has an auxiliary switch which initially connects the selector contact on the new tap in series with a circulating current-limiting inductor and the load to prevent load circuit interruption and then opens the previous tap circuit so that circulating current is interrupted at reduced voltage and then short circuits the inductor to complete the tap change, whereby the inductor is energized only momentarily.

Abstract: An electrical control for providing a graduated change in the magnitude of electrical energy transferred from a source of electrical energy to a device driven thereby including a mount, a plurality of load contacts disposed in fixed relation on the mount, a movable power contact engaging certain of the plurality of load contacts, a movable transition contact associated with the movable power contact first engaging each of the load contacts engaged by the movable power contact to provide an alternate full load current path through each of the load contacts engaged by the movable power contact prior to engagement by the movable power contact, thus providing a transition between the load contacts engaged by the movable power contacts which are connected to differing magnitudes of impedance substantially without arcing; and a third movable contact may be provided for selectively engaging other of the plurality of load contacts for effecting a switching function.

Abstract: Tap changing apparatus for switching the turns ratio between the primary and secondary windings of a three-phase transformer. The tap changer includes three mounting boards, one for each phase of the transformer. Each board contains a plurality of stationary contacts arranged in a circular pattern around an axis of rotation and connected to taps from various sections of the transformer windings. A movable contact assembly is associated with each set of stationary contacts and is rotatable around the center axis of each respective contact set. Each movable contact assembly is affixed to a worm gear which operates to rotate the movable contacts between successive stationary contacts in each respective contact set.

Abstract: A three-phase transformer including tap changing apparatus for switching the turns ratio between the primary and secondary windings of the transformer. The tap changer includes a mounting board on which three contact sets are mounted; each set having a plurality of stationary contacts arranged in a circular pattern. A circular-shaped operating member, with a movable contact assembly affixed thereto, is associated with each contact set and is pivotable around the center of the stationary contact set to allow the movable contact assembly to sequentially engage successive stationary contacts. A connecting bar is coupled to each operating member in spaced relation from its axis of rotation, causing all three operating members to rotate together.

Abstract: Tap changing apparatus for connection to the windings of a three-phase power transformer. The tap changer includes a mounting board on which three sets of stationary contacts, arranged in a circular pattern, are mounted. A rotating contact assembly is associated with each set of stationary contacts and may be pivoted around the center of the stationary contact set for engagement with one of the stationary contacts. An operating bar extends across each set of stationary contacts and is coupled to the rotating contacts by rack and pinion assemblies. When the operating bar is moved in one direction, the rotating contacts are turned in a counterclockwise direction. When the operating bar is moved in the other direction, the rotating contacts are turned in the clockwise direction. The operating bar is moved by a rack and pinion assembly which is connected to a rotating shaft.

Abstract: Cylindrical tap terminals are attached to a base plate and are positioned symmetrically around an opening in the base plate. A contact carrier is positioned in the base plate opening and is dimensioned for rotation therein. A movable contact blade is disposed in a radial opening in the contact carrier and is dimensioned to connect together two adjacent tap terminals. A shaft with an inclined surface thereon extends into another opening in the contact carrier and is coupled to an operating handle. The handle may be pulled to move the inclined surface and permit movement of the contact blade away from the tap terminals. Rotation of the handle rotates the shaft, the contact carrier, and the contact blade to another position. When in position, a coil spring forces the inclined surface against the contact blade to maintain adequate electrical contact pressure between the blade and the tap terminals.

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.