Abstract: Disclosed is a device and method for reducing network feedback during operation of an electric-arc furnace (10). The electric-arc furnace (10) has three lines (7) with one electrode (4) each. A sensor (15) for measuring the currently flowing current and a sensor (16) for measuring the currently applied voltage are provided in each line. A control and regulating unit (30) calculates an electrical actual value (Eist1, Eist2, Eist3). A semiconductor tap changer (20) is assigned to the furnace transformer (6) such that, by suitably selecting three target winding taps (TSOLL1, TSOLL2, TSOLL3) of a primary side (P) of the furnace transformer (6), a target current (IS1, IS2, IS3) is adjustable in each line (7).

Abstract: 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.

Abstract: What is disclosed is: an on-load tap changer (1). The on-load tap changer (1) comprises a diverter switch insert (14) and a vacuum interrupter (15), which is rotatable about an axis (A) and to which at least one switching module (24) is assigned. The switching module (24) comprises at least one switching segment (25) fastened on the vacuum interrupter (15) and an associated resistor arrangement (27). An actuating arrangement (41) is assigned to the switching module (24) on an inner wall (20) of an oil tank (18). In accordance with the invention, the resistor arrangement (27) has a plurality of resistor elements (28). In addition, the actuating arrangement (41) comprises a plurality of physically identical actuating elements (50), which are assigned to the switching module (24) on the inner wall (20) of the oil tank (18).

Abstract: The invention relates to a control transformer that is designed as a phase-shifting transformer, wherein semiconductor switching components are provided for each phase at a regulating winding with several partial windings. According to the invention, an additional connecting line with an additional electronic switching component is provided in each phase wherein each of these connecting lines connects a module of the respective phase with the end of the main winding of the adjacent phase.

Abstract: Disclosed is an on-load tap changer comprising a connection to an insulating liquid of a transformer. The on-load tap changer in a housing (9) and the transformer are in the transformer tank (7) and are surrounded by insulating liquid (6). At least one opening (10) is formed in the housing base (9B) and/or housing cover (9M), said opening providing a fluidic connection between the insulating liquid in the transformer tank and the insulating liquid in the housing.

Abstract: A tap changer for uninterrupted switching over between winding taps of a tapped transformer has two load branches each for a respective phase to be switched. Each load branch has a vacuum switching contact acting as main contact and parallel thereto at least one series connection of a switch-over resistance and a respective further vacuum switching contact. The two load branches are connected with a common load shunt or connectable by mechanical switching elements. Two respective vacuum switching contacts of each load branch are constructionally combined to form a single vacuum switching tube with two separate movable contacts actuatable independently of one another and a common fixed contact. The common fixed contact is connected with the common load shunt or connectable mechanical switching contacts.

Abstract: Disclosed are an apparatus and method for process-based power regulation of an electric arc furnace (10). A plurality of sensor types (15, 16, 17) detect presently active operating parameters of the electric arc furnace (10) in dependence on time. From the measured values, a control and regulating unit (30) determines the necessity of whether to switch other winding taps (TS1 . . . TSN) of the primary side (6P) of the furnace transformer (6) by a semiconductor tap changer (20) in order to effect a modified electrical power to prevent thermal and/or mechanical damages to the electric arc furnace (10).

Abstract: The invention relates to a transformer with a tap changer, wherein optionally the primary or secondary side can be regulated by the tap changer, and wherein, on the side of the transformer to be regulated, a main winding and at least one regulating winding, which is connectable by the tap changer, are provided. According to the invention, the main winding is divided into two main winding parts, and the at least one regulating winding and the tap changer (3) connecting the regulating winding are arranged electrically between the two main winding parts (1, 2).

Abstract: Disclosed is a device and method for reducing network feedback during operation of an electric-arc furnace (10). The electric-arc furnace (10) has three lines (7) with one electrode (4) each. A sensor (15) for measuring the currently flowing current and a sensor (16) for measuring the currently applied voltage are provided in each line. A control and regulating unit (30) calculates an electrical actual value (Eist1, Eist2, Eist3). A semiconductor tap changer (20) is assigned to the furnace transformer (6) such that, by suitably selecting three target winding taps (TSOLL1, TSOLL2, TSOLL3) of a primary side (P) of the furnace transformer (6), a target current (IS1, IS2, IS3) is adjustable in each line (7).

Abstract: Disclosed is a device and a method for regulating an electric arc furnace (10) in the initial phase of a smelting process. A sensor (16) for measuring the present voltage and a sensor (15) for measuring the presently flowing current are provided in each line (7) of the electric arc furnace (10). The actual impedance (Zist) is time-dependently calculated by a control and regulating unit (30). An on-load tap changer (20) that is constructed as a semiconductor tap changer, is assigned to a furnace transformer (6) with a primary side (6P) and a secondary side (6S). The semiconductor tap changer (20) realizes a cycle time of a few milliseconds.

Abstract: The invention relates to an on-load tap changer for switching among winding taps of a step transformer without interruption. According to the invention, in each auxiliary current branch of the on-load tap changer, which operates with vacuum switching tubes as switching elements, additional switches are provided in series with the vacuum switching tubes and the respective winding tap. Said additional switches cause a complete galvanic isolation of the vacuum switching tubes in the auxiliary current branches in steady-state operation.

Abstract: The invention relates to a control transformer that is designed as a phase-shifting transformer, wherein semiconductor switching components are provided for each phase at a regulating winding with several partial windings. According to the invention, an additional connecting line with an additional electronic switching component is provided in each phase wherein each of these connecting lines connects a module of the respective phase with the end of the main winding of the adjacent phase.

Abstract: The invention relates to a transformer with a tap changer, wherein optionally the primary or secondary side can be regulated by the tap changer, and wherein, on the side of the transformer to be regulated, a main winding and at least one regulating winding, which is connectable by the tap changer, are provided. According to the invention, the main winding is divided into two main winding parts, and the at least one regulating winding and the tap changer (3) connecting the regulating winding are arranged electrically between the two main winding parts (1, 2).

Abstract: The invention relates to a tap changer for voltage regulation, comprising semiconductor switch units (S1.1, . . . , S1.6; S2.1, . . . , S2.6) on a variable transformer having a regulating winding, wherein two parallel load branches (1, 2) are provided, in each of which several series-connected semiconductor switch units are arranged. Parts of the regulating winding (W1, W2, W3) and bridges (B1, B2) are provided alternately and run parallel between the two load branches, alternating such that by corresponding connection of the semiconductor switch units in both load branches, the parts of the regulating wiring can be operated arbitrarily in a subtractive and/or additive manner.

Abstract: The invention relates to a stepping switch for voltage control, comprising semiconductor switch elements on a variable transformer having associated regulating windings. The stepping switch has a modular design, wherein each module comprises a respective sub-winding of the regulating winding which can be activated or deactivated by semiconductor switch elements.

Abstract: The invention relates to an on-load tap changer comprising semiconductor switching elements for uninterrupted switching between winding taps of a tapped transformer. According to the invention, contact bars are provided which extend in the direction of the path of the fixed tap contacts and can be contacted using contact bridges that can be jointly moved by a contact slide in such a way that direct electrical connections to the charge diverter and electrical connections to the inputs and the output of the semiconductor switching elements can be established.

Abstract: The invention relates to the arrangement of a stepping switch on a control transformer, wherein either only the mechanical contact system (8) of the stepping switch or also its load changeover switch (7) is or are arranged within the tank (1) of the transformer, under the transformer cover (4) and above the iron yoke (3).

Abstract: The invention relates to an on-load tap changer comprising semiconductor switching elements for uninterrupted switching between fixed tap changer contacts which are electrically connected to winding taps of a tapped transformer. Each of the fixed tap changer contacts can be connected to a charge diverter either directly or, during switching, via the semiconductor switching elements that are connected therebetween. According to the invention, the charge diverter has fixed, divided diverting contact pieces in order for the semiconductor switching elements to be electrically isolated from the transformer winding during stationary operation.

Abstract: The invention relates to a tap changer for regulating voltage, comprising semiconductor switching elements on a regulating transformer having a regulating winding. The tap changer is modularly constructed, wherein each module comprises a sub-winding of the regulating winding that can be switched on or off by semiconductor switching elements.

Abstract: A tap changer for uninterrupted switching over between winding taps of a tapped transformer has two load branches each for a respective phase to be switched. Each load branch has a vacuum switching contact acting as main contact and parallel thereto at least one series connection of a switch-over resistance and a respective further vacuum switching contact. The two load branches are connected with a common load shunt or connectable by mechanical switching elements. Two respective vacuum switching contacts of each load branch are constructionally combined to form a single vacuum switching tube with two separate movable contacts actuatable independently of one another and a common fixed contact. The common fixed contact is connected with the common load shunt or connectable mechanical switching contacts.