Abstract: A tap changer in which a pair of selector contacts can be jointly movable or individually movable to engage stationary tap contacts of an array and one of the selector contacts is in series with a tickler coil and switchover resistor connected to one fixed contact of a bypass switch whose movable contact is connected to the load. The other selector contact is connected to one stationary contact of a switchover switch whose movable contact is connected to a second contact of the bypass switch while another contact of the switchover switch is tied to a point between the tickler coil and the resistor. A pair of oppositely poled parallel thyristors bridges the auxiliary network of the tickler coil and resistor and the main branch passing from the switchover switch to the bypass switch. The movable contacts are operated by an intermittent drive of the Geneva mechanism type.

Abstract: A motor-driven step switch for step transformers includes a drive motor connected to the step switch, display, input, and control units, a controller for actuating the drive unit in accordance with rotation direction, an information unit which obtains and transmits the step position and which is connected with the controller which delivers commands for controlling the drive motor and a switching operation, and an electrical connection between the controller and display, input, and control units. In accordance with this invention the information unit has a sensor for determining the absolute value of the actual position of the step switch, a nonvolatile memory unit for storing the position of the step switches with a range of step positions, and a unit for determining an end position of the step switch.

Abstract: A tap changing circuit has each tap of a power transformer connected with a selector vacuum switching cell. The odd numbered cells and the even numbered cells are connected to respective sides of a load switch each including a further vacuum switching cell. The sides are bridged by a transition inductor or resistor.

Abstract: The invention relates to a load selector for step switches in step transformers with two movable selector contacts. A suitable vacuum switch is located downstream of the first movable selector contact to switch the load current and a suitable switch for switching the compensation current is located downstream of the second movable selector contact. Both of the selector contacts are independently movable in such a way that one of the selector contacts moves slowly and the other selector contact rapidly moves or jumps between positions. The sequence of operation of the selector contacts is independent of the switching direction.

Abstract: A cast-resin transformer has a transformer housing, a plurality of windings each having a plurality of taps, respective contacts connected to the taps and mounted on the housing in respective arrays which are all identical, and respective identical mounting elements on the housing at each of the contact arrays. Respective identical step switches each serve a respective winding of the transformer and each have a switch housing secured to the respective mounting element of the transformer housing at the respective contact array and a step contact movable along the respective connector elements and electrically engageable therewith. A drive motor and a main shaft are connected to all of the step contacts for synchronously stepping the step contacts along the respective connector elements.

Abstract: A step-transformer drum formed with throughgoing apertures each centered on a respective axis has a contact assembly in each aperture having an insulating washer lining the aperture and having an inside part lying on an inside surface of the drum and an outside part lying on an outside surface of the drum. A stud has an enlarged head bearing outward on the inside washer part and a shaft projecting through the washer past the outside washer part and formed outside the outside washer part with a transversely throughgoing hole. A pin extends transversely through the hole and bears inwardly on an outwardly directed ramp so that rotation of the stud and pin in one direction relative to the structure makes the pin ride up on the ramp and tightens the stud in the aperture and opposite relative rotation loosens the stud.

Abstract: An actuator used with a load switch having a rotary drive shaft extending along a drive axis and carrying a cam and with an interrupter having an operating rod displaceable longitudinally of itself and generally perpendicular to the drive axis has a frame defining upper and lower pivots having respective upper and lower axes spaced from each other and generally parallel to the drive axis. An output parallelogrammatic linkage has an output link having upper and lower ends, movable between an upper and a lower position, and formed with an aperture alignable axially with the input-link aperture and an output coupling formation connected longitudinally on the rod so that on movement between the upper and lower positions the interrupter is operated. An input parallelogrammatic linkage has an input link formed with an aperture and an input coupling formation bearing radially on the cam so that rotation of the cam vertically displaces the input link between its upper and lower positions.

Abstract: A stepper drive for a step-type transformer has an upper geneva wheel rotatable about a wheel axis, a lower geneva wheel spaced below the upper wheel and also rotatable about the axis, and a driver rotatable about a driver axis adjacent the wheels and having an upper abutment engageable with the upper wheel and a lower abutment engageable with the lower wheel and offset by about 180.degree. relative to the driver axis from the upper abutment. A selector abutment is provided on the upper wheel offset from the axis thereof. A selector lever pivotal about a selector axis offset from the wheel axis is engageble with the selector abutment in end positions of the upper wheel. A blocking plate shiftable radially on the lever between an actuated position and an unactuated position is urged by a spring into the unactuated position.

Abstract: A multiphase stepping transformer wherein a closed vacuum interrupter at each phase is opened before a respective stepping switch is advanced is controlled by continuously monitoring current flow through the interrupters. Before the interrupters are opened an error signal is generated unless all of the monitored current flows lie to one side of a predetermined threshold. After the interrupters are opened an error signal is generated if current flow is detected through any of the interrupters. Advance of the stepping switches is blocked on generation of any error signal. The apparatus includes for each interrupter a respective current detector, a light-emitting diode energized by the respective detector, a light receiver associated with each diode, and a light-transmitting cable connecting each diode with the respective receiver.

Abstract: A switching system for a step transformer having at least two adjacent taps and a pair of terminals shiftable between the taps has a pair of fixed contacts normally connected to the terminals, a vacuum interrupter connected between the terminals and displaceable between an open-circuit position and a closed-circuit position, a pair of movable contacts each engageable with a respective one of the fixed contacts and forming therewith a respective bypass switch, and a cam rotatable about a cam axis and having a contact face and an axially oppositely facing interrupter face each formed with a respective operating formation. A drive rotates the cam about its axis through steps of a half revolution. A respective cam follower engaged between each of the movable contacts and the contact-face formation opens and closes one of the bypass switches on rotation of the cam through a half revolution and thereafter opens and closes the other of the bypass switches on rotation of the cam through a succeeding half revolution.