A system for determining when an electrical contact or other component reaches a predetermined temperature. In operation, a trace material is dispersed into a surrounding environment (e.g., head space within a compartment above insulating oil), where the trace material is detected. A barrier may be ruptured or broken by temperature-induced gas pressure, or pierced by a spring-loaded member that is located within the same section that contains the trace material, and devices may be provided for moving the trace material through the foil barrier as the barrier is ruptured. The barrier may be opened solely by internal gas pressure. According to another embodiment, improved fail-safe operation may be achieved by providing a spring-loaded member and configuring the barrier to be ruptured by the pressure of the detectable gas material before the barrier is ruptured by the spring-loaded member.

A system for determining when an electrical contact or other component reaches a predetermined temperature. In operation, a trace material is dispersed into a surrounding environment (e.g., head space within a compartment above insulating oil), where the trace material is detected. A barrier may be ruptured or broken by temperature-induced gas pressure, or pierced by a spring-loaded member that is located within the same section that contains the trace material, and devices may be provided for moving the trace material through the foil barrier as the barrier is ruptured. The barrier may be opened solely by internal gas pressure. According to another embodiment, improved fail-safe operation may be achieved by providing a spring-loaded member and configuring the barrier to be ruptured by the pressure of the detectable gas material before the barrier is ruptured by the spring-loaded member.

A circuit (15) for an electrical plant (10) with a first and a second control winding (11, 13) comprises a first on-load tap changer (16) with a first diverter terminal (161) and three first switch terminals (162), of which at least two can be connected with associated first taps (12) of the first control winding (11); and a second on-load tap changer (17) with a second diverter terminal (171) and three second switch terminals (172) of which at least two can be connected with associated second taps (14) of the second control winding (13);
wherein the second diverter terminal (171) is connected with the first diverter terminal (161) or with a first switch terminal (162) not associated with the first tap (12).

A load selector for tapped transformers has an oil tank and a preselector having a first preselector contact and a second preselector contact for each phase to be switched by the load selector. The first preselector contact and the second preselector contact are mounted on a wall of the oil tank and extending through the wall of the oil tank. A first zero contact and a second zero contact separate from the first zero contact are provided for each phase to be switched by the preselector. The first zero contact and the second zero contact are each mounted on the wall of the oil tank and extend through the wall of the oil tank.

An on-load tap changer has a load changeover switch insert having a switching tube rotatable about an axis, at least one switching module associated with the switching insert and having at least one switching segment fastened to the switching tube, an oil tank, and a resistor subassembly having a plurality of separate and identical resistors. An actuating arrangement associated with the switching module at an inner wall of the oil tank has a plurality of identical actuators associated with the switching module at the inner wall of the oil tank. The on-load tap changer is a load selector or a load changeover switch depending on the arrangement of the at least one identical switching segment, the resistor subassembly, and the mounting of the plurality of identical actuators at the inner wall of the oil tank.

The invention relates to a switching system for a tapped transformer with on-load tap changer wherein the tapped transformer comprises a main winding with a first main terminal; a coarse winding with a first coarse terminal and with a second coarse terminal; a control winding with a first control terminal; and an on-load tap changer that has a switch terminal and that interacts with the control winding;
the switching system comprising a lead; a first switch subassembly comprising a first main fixed contact that can be connected to the first main terminal; a first coarse fixed contact that can be connected to the first coarse terminal; a first control fixed contact that can be connected to the first control terminal; a first switch fixed contact that can be connected to the first switch terminal; and a first movable bridge contact that is formed such that it electrically bridges or connects at least two fixed contacts of its switch subassembly in each stationary operating position of the switching system and/or during each switch over process of the switching system; a second switch subassembly comprising a second coarse fixed contact that can be connected to the second coarse terminal; a second control fixed contact that can be connected to the first control terminal and/or that is connected to the first control fixed contact; a second switch fixed contact that can be connected to the switch terminal and/or that is connected to the first switch fixed contact; and a second movable bridge contact that is formed such that it electrically bridges at least two fixed contacts of its switch subassembly in each stationary operating position of the switching system and/or during each switch-over process of the switching system; and a third switch subassembly comprising a first lead fixed contact that is connected to the lead; a third coarse fixed contact that can be connected to the first coarse terminal and/or that is connected to the first coarse fixed contact; a third control fixed contact that can be connected to the first control terminal and/or that is connected to the first control fixed contact; a third switch fixed contact that can be connected to the switch terminal and/or that is connected to the first switch fixed contact; and
a third movable bridge contact that is formed such that it electrically bridges at least two fixed contacts of its switch subassembly in each stationary operating position of the switching system and/or during each switch over process of the switching system.

There is provided a tap changer in which movable contacts rotate to be selectively connected to a plurality of taps. The tap changer includes a rotatable upper movable contact; a rotatable lower movable contact electrically connected to the upper movable contact; a driving shaft rotating the upper movable contact and the lower movable contact integrally; a single-type fixed contact including a single terminal connected to any one of a plurality of taps; and a dual-type fixed contact including a first terminal and a second terminal connected together to another of the plurality of taps. Since the upper movable contact and the lower movable contact are integrally rotated through the single driving shaft, the number of components and volume of the device may be reduced and an operation of the device may be facilitated.

The invention relates to a linear selector (1) for power-free preselection of tap contacts for a tapped transformer (100). The linear selector (1) according to the invention is cost-effective, simple and compactly constructed. The functions of a selector and a reverser are thus better connected. The linear selector (1) is constructed from a fine selector (2) and a reversing switch (3). The fine selector (2) and the reversing switch (3) are directly driven via a common gear unit (6).

A system for operating an on-load tap changer (OLTC) includes a plurality of legs that include mechanical switches. At least one leg switches from a first to a second tap of the OLTC on receipt of a tap change signal. At least one mechanical switch is activated to establish an electrical connection between one of the first and the second tap and a power terminal of the OLTC. Further, the system includes semiconductor switches that are parallel to the mechanical switches and when activated electrically couple one of the first and the second tap and the power terminal. The system includes a processing unit that selectively activates and deactivates the mechanical and semiconductor switches in such a way that electrical contact is maintained between at least one of the taps and the power terminal during the transition of at least one leg from the first tap to the second tap.

A dry transformer load switch, and transformer having such switch, has a hollow insulation cylinder extending longitudinally about a virtual center axis and has a plurality of connection contacts arranged along the inner circumference thereof, and a radially oriented main contact arranged in the interior of the hollow insulation cylinder so as to be rotatable about the center axis and which, with a corresponding rotary movement, can be optionally electrically connected by the radially outer end thereof to one of the connection contacts. In a hollow-cylindrical space about the center axis that is defined by the radially inner and outer end of the main contact, there is a barrier shield, which can be rotated together with the main contact about the axis.