Device for limiting short-circuit currents in on-load tap changers and on-load tap changer having such device

Abstract

The present invention relates to an installation 1 for limiting short-circuit currents in an on-load tap changer 2, in particular in a diverter switch 8 of the on-load tap changer 2, comprising a first sensor 3 for measuring the current in a first power line 4 of the on-load tap changer 2, a disconnecting element 5, a control device 6 and a current-limiting element 7, wherein the disconnecting element 5 is arranged in the first power line 4 of the on-load tap changer 2 and the current-limiting element 7 is arranged in parallel with the disconnecting element 5, and the first sensor 3 is configured to send a first measurement signal M1 indicative of the measured current in the first power line 4 of the on-load tap changer 2 to the control device 6, and the disconnecting element 5 is operable by the control device 6 such that the disconnecting element 5 can interrupt the current flow in the first power line 4 of the on-load tap changer 2 so that the current flowing therethrough is diverted to the current-limiting element 7.

Description

[Technical field]

[0001] The present invention relates to an on-load tap changer, in particular to an arrangement for limiting short-circuit currents in a changer switch of an on-load tap changer, and to an on-load tap changer including an arrangement for limiting short-circuit currents in this on-load tap changer. [Background technology]

[0002] As is known, on-load tap changers are used to switch between different winding taps of a control winding of a tap transformer without interruption and thus to control the voltage. These winding taps are generally composed of a selector for preselecting, in a current-free state, the winding tap of the tap transformer that has to be changed and a changeover switch for the actual changeover from the previously connected winding tap to the newly selected winding tap without interruption. To preselect these winding taps in a current-free state, the selector generally has two movable selector contacts that connect to these winding taps. To actually change the load, the changeover switch generally has a number of changeover contacts and a number of resistors. The changeover contacts are arranged in the main load branch of the on-load tap changer and are used to directly connect the winding tap connected by the respective selector contact to the load conductor via the main load branch. These resistors are used to briefly limit the circulating current flowing through the changeover switch during the changeover process and are also called transition resistors.

[0003] If an on-load tap changer does not operate according to regulation, it may be at fault. A possible fault is a short circuit in the on-load tap changer, more precisely in the changeover switch, caused by a flashover between two main load branches. Since the two main load branches are electrically connected to one winding tap of the control winding via one selector contact each, this may cause an inter-tap short circuit. Precisely this means that the short circuit current flows through the main load branches, the selector contacts and the control tap of the control winding of the tap transformer.

[0004] To protect transformers from greater damage or destruction in the event of a short circuit, power grids are equipped with circuit breakers that can reliably interrupt high currents in the event of an abnormality. However, to interrupt, the circuit breakers require a relatively long time, e.g. 50 ms. During this period, the short circuit current flows unrestrictedly through the on-load tap changers and conductive components of the transformer. The short circuit current can cause serious damage to the on-load tap changers and the control windings of the transformer. Such damage must be avoided. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] European Patent Application Publication No. 00052521 [Patent Document 2] German Patent No. 19953551 Summary of the Invention [Problem to be solved by the invention]

[0006] Against this background, the invention proposes the subject matter of the independent claims. Preferred embodiments of the invention are set out in the dependent claims.

[0007] The improved concept is based on the idea of ​​providing a facility which, in the event of a short circuit in the changeover switch of an on-load tap changer, recognises this short circuit sufficiently quickly and allows the increasing short circuit current to be diverted to a resistor before it reaches a limiting value, which limits this current to an admissible value until a higher-level protection system, e.g. a circuit breaker, trips and isolates the transformer from the grid. [Means for solving the problem]

[0008] According to a first aspect, the invention proposes an arrangement for limiting short-circuit currents in an on-load tap changer, in particular in a changer switch of the on-load tap changer, which comprises a first sensor for measuring a current in a first power line of the on-load tap changer, a disconnecting element, a control device and a current limiting element. The disconnecting element is arranged in the first power line of the on-load tap changer. The current limiting element is arranged in parallel to the disconnecting element, i.e. in parallel to the first power line. The first sensor is configured to transmit a first measurement signal to the control device which is indicative of the measured current in the first power line of the on-load tap changer. The current measurement and the transmission of the measurement signal can be performed continuously or without interruption in time, preferably with a sampling rate of less than 1 microsecond. The transmission of the measurement signal to the control device can be performed wirelessly, by optical fiber or preferably by wire, particularly preferably by shielded wire.

[0009] The sensor is preferably configured as a current transformer, but any kind of sensor can be used to implement the solution according to the invention, which can continuously measure the time course of the current in a conductor and further transmit it as a measurement signal to a control device.

[0010] The control device is in particular adapted to capture and / or ascertain the time course of a measurement signal representative of the measured current.

[0011] The first sensor may be arranged outside the housing of the respective current transformer (whose voltage is controlled by the on-load tap changer), preferably on the lid of the housing of the transformer, or inside the housing of the transformer.

[0012] The current limiting element is operable by the controller such that the current limiting element can interrupt the flow of current in the first power line of the on-load tap changer such that current conducted in the first power line is diverted, i.e. conducted, to a parallel path having the current limiting element and limited by the current limiting element.

[0013] According to a preferred embodiment, the first power line electrically connects the selector, in particular the first movable selector contact, and the on-load tap changer, in particular the first main load branch of the on-load tap changer, to each other.

[0014] According to an embodiment, the interruption element is arranged in a part of the first power line which is outside the on-load tap changer, i.e. outside the selector and the diverter switch.

[0015] According to another embodiment, the interrupting element has a switching time for interrupting the current flow that is shorter than 1.0 ms, in particular shorter than 0.5 ms, particularly preferably shorter than 0.1 ms, Due to the short response time of the interrupting element, the increasing short-circuit current is diverted to the current-limiting element before the short-circuit current reaches a limit value.

[0016] The interrupting element may be arranged on the outside of the transformer housing, preferably on the lid, or on the inside of the transformer housing.

[0017] According to further embodiments, the interruption element is configured as a semiconductor element, or as a non-electrical or electric detonator, or as a mechanical contact device with an electric drive.

[0018] The semiconductor elements can be configured, for example, as IGBTs and / or thyristors. Non-electrical detonators and also electrical detonators for disconnecting electrical connections such as cables or tracks are known from the prior art. Suitable disconnecting means are cutting charges, in particular of pyrotechnics, as described, for example, in EP 00052521 A1, or so-called "I" detonators. S Current limiter (I S -Begrenzer) detonators, which have been used for the past ten years in medium-voltage applications. A mechanical contact device with an electric drive, which can be configured as a contact system, for example as described in DE 199 53 551 C1, is likewise a means by which the current in the first power line can be interrupted.

[0019] All these shutoff elements have the advantage of having very short switching or operating times in the range of 0.1 to 1.0 ms.

[0020] According to a preferred embodiment, the current limiting element is designed for a current strength that corresponds to a multiple of the rated current of the on-load tap changer, for example twice the rated current. The rated current, also called rated carry current in the relevant standards, is the current measured during sustained operation of the on-load tap changer. Thus, such that a current limiting element of the on-load tap changer having a rated current of 800 A is able to limit a short-circuit current to 1600 A for a short period of time, for example 50 ms, the current limiting element is designed according to this preferred embodiment of the invention.

[0021] The current limiting element may be configured as a resistor, for example as an ohmic resistor, as a PTC thermistor, as a circuit breaker with a fuse element or as an inductance, in particular as a coil. The installation resistor, preferably one of a plurality of transition resistors in a changeover switch of the on-load tap changer, may be connected in parallel to the first power line.

[0022] According to a preferred embodiment, the arrangement for limiting the current comprises, in addition to the first sensor, a second sensor for measuring the current in a second power line of the on-load tap changer. This second sensor is configured to transmit a second measurement signal indicative of the measured current in the second power line of the on-load tap changer to the control device. The second power line electrically connects in particular a selector, preferably a second movable selector contact, and a diverter switch, in particular a second main load branch of a diverter switch. The second sensor is preferably configured similarly to the first sensor and the second measurement signal is preferably configured similarly to the first measurement signal. The second sensor can be arranged outside the housing of the transformer, in particular on a lid, or inside the housing of the transformer.

[0023] According to an embodiment, the control device is configured to operate the blocking element if both the first measurement signal and the second measurement signal are above a predetermined limit value.

[0024] The controller determines, based on the first measurement signal and the second measurement signal, whether both the measured current in the first power line and the measured current in the second power line have reached or exceeded the limit value, and operates the interruption element if the limit value has been reached or exceeded.

[0025] According to one embodiment of the invention, the predefined limit value is a maximum value of current which is a multiple of the rated current of the on-load tap changer (2). Thus, according to this embodiment of the invention, for example, for an on-load tap changer with a rated current of 800 A, the limit value is established at a maximum value of current of 1600 A. This means that the interruption element is measured by the control device when a current of at least 1600 A is measured on both the first power line and the second power line.

[0026] According to another embodiment, the predefined limit value is the maximum change within a preset period of time. For example, a limit value according to this embodiment for an on-load tap changer designed for a rated current of 800 A is 1.2 A / μs. This means that the interruption element is operated by the control device when the current measured in the first power line and in the second power line increases by a value of 1.2 A or more within 1 microsecond. This has the advantage that an occurring short-circuit current can be recognized quickly, for example within 1 microsecond, because a faster increase in the current is detected early by the sensor and the control device.

[0027] According to a second aspect, the invention proposes an on-load tap changer for switching between a number of winding taps of a tap transformer without interruptions, the on-load tap changer comprising a selector for preselecting in a current-free state to a selected winding tap, a changeover switch for the actual changeover from the previous winding tap to the preselected winding tap, and a first power line electrically connecting the selector and the changeover switch to each other, preferably electrically connecting a first selector arm and a first main load branch to each other. Furthermore, the on-load tap changer of the invention comprises an on-load tap changer configured according to the first aspect of the invention for limiting short-circuit currents in the on-load tap changer, in particular in a changeover switch of the on-load tap changer. With regard to the installation, reference is made to the above description, preferably features and / or advantages as already explained for the first aspect of the invention or the corresponding preferred embodiments.

[0028] According to a preferred embodiment, the on-load tap changer comprises a second power line electrically connecting the selector and the diverter switch, preferably electrically connecting a second selector arm and a second main load branch. Furthermore, in this embodiment, the installation comprises a second sensor for measuring the current in the second power line. The second sensor is configured to transmit a second measurement signal indicative of the measured current in the second power line of the on-load tap changer to a control device.

[0029] According to a third aspect, the invention proposes a method for limiting short-circuit currents in an on-load tap changer, in particular in a changer switch of the on-load tap changer, the on-load tap changer being configured according to the second aspect of the invention and comprising an installation configured according to the first aspect of the invention. The method comprises the steps of: measuring the current in a first power line of the on-load tap changer by means of a first sensor, transmitting a first measurement signal indicative of the measured current in the first power line of the on-load tap changer from the first sensor to a control device, and operating a blocking element arranged in the first power line of the on-load tap changer such that the current flow in the first power line of the on-load tap changer is interrupted and the current is diverted to a current limiting element. The current limiting element is arranged in parallel to the blocking element, in particular in a current path parallel to the first power line.

[0030] These steps of the method correspond to the features of the installation according to the first aspect of the invention and to the features of the on-load tap changer according to the second aspect of the invention. Therefore, with regard to the method according to the third aspect of the invention, reference is made to the above descriptions, preferably features and / or advantages as already explained for the installation and on-load tap changer according to the second and third aspects of the invention.

[0031] According to a preferred embodiment of the method, the method comprises further steps, according to which in addition to measuring the current in the first power line, the current in the second power line of the on-load tap changer is measured by a second sensor and in addition to transmitting the first measurement signal, a second measurement signal indicative of the measured current in the second power line of the on-load tap changer is transmitted from the second sensor to the control device. Furthermore, the first and second measurement signals are compared by the control device with predefined limit values ​​and the interruption element is operated if both the first and the second measurement signals are equal to or greater than predefined limit values. With regard to this preferred embodiment of the method, reference is made to the above description, preferably to features and / or advantages as already explained for the corresponding preferred configuration of the installation.

[0032] Other configurations and steps of the method follow directly from the various configurations of the equipment.

[0033] The present invention will be described in detail below on the basis of representative embodiments with reference to the drawings, in which all the individual features described and / or all the individual features shown and any combination thereof constitute the subject matter of the present invention independently of the features described in the individual claims or the dependent claims of the individual claims. Components that are identical or functionally identical or have the same effect may be indicated with the same reference numerals. Components that are identical or have the same function are described only for the drawing in which they possibly first appear. The description is not necessarily repeated in the subsequent figures. [Brief description of the drawings]

[0034] [Figure 1] FIG. 1 is a schematic diagram of an exemplary embodiment of an on-load tap changer. [Diagram 2] FIG. 1 is a schematic diagram of a first embodiment of the installation. [Diagram 3] FIG. 2 is a schematic diagram of a second embodiment of the installation. [Figure 4] FIG. 2 is a schematic diagram of a second embodiment of the installation. [Diagram 5] 1 is a first embodiment of a method for limiting a short circuit current; [Figure 6] FIG. 4 is a schematic diagram of a second embodiment of the method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] 1 shows a schematic representation of an exemplary embodiment of an on-load tap changer 2 for a tap changer 20. The tap changer 20 comprises a main winding 25 and a number of different winding taps N1,...,N2 which are connected or disconnected by the on-load tap changer 2. J ,...,N N For this reason, the on-load tap changer 2 is provided with two movable selector contacts for selecting different winding taps N1, ..., N J ,...,N N 1, and a changeover switch 8 for switching from the actually connected winding tap to a preselected new winding tap. In the position of the changeover switch 8 shown in FIG. J+1 from the load conductor 12 via the respective selector contact and the change-over switch 8.

[0036] In Fig. 2 a first embodiment of the installation according to the invention is shown diagrammatically. The installation 1 is used for limiting short-circuit currents in an on-load tap changer 2, in particular a diverter switch 8, in the event of a fault. The diverter switch 8 has a number of changeover contacts and a number of resistors for said changeover. However, the specific circuit arrangement of the diverter switch 8 is not essential to the implementation of the invention. It will therefore not be described in detail. The on-load tap changer 2 is connected to each one of the winding taps N of a control winding of a tap transformer (not shown). J,J+1The installation 1 comprises a selector 11 having two movable selector arms contacting the on-load tap changer 2 and the on-load tap changer 3. The installation 1 comprises a first sensor 3 arranged on the first power line 4 and a second sensor 9 arranged on the second power line 10. The sensors 3, 9 are used to continuously measure the currents flowing in the respective power lines 4, 10 and to continuously transmit the measured currents as measurement signals M1, M2 to the control device 6. The sensors 3, 9 transmit the measurement signals M1, M2 to the control device 6, for example via a signal connection 13. The first power line 4 connects a first movable selector contact of the selector 11 to a changeover switch 8 of the on-load tap changer 2. Similarly, the second power line 10 connects a second movable selector contact of the selector 11 to the changeover switch 8. A disconnecting element 5 is arranged on the first power line 4. The interrupting element 5 is configured as an IGBT switch according to the first embodiment, which is designed and operable in such a way that it is able to divert a short-circuit current occurring in the diverter switch 8 in the event of a fault. The semiconductor switching element 5 is operated by the control device 6 when both the first measurement signal M1 and the second measurement signal M2 are above a predefined limit value. The current flow in the first power line 4 is then interrupted by the semiconductor switching element 5. This current is then diverted to the current limiting element 7. Here, the current limiting element 7 is configured, for example, as an ohmic resistor and is arranged in parallel to the semiconductor switching element 5 or in a current path 14 parallel to the first power line 4 and is designed in such a way that it is able to limit the increasing short-circuit current until a higher-level protection system, for example a power switch, is activated and the corresponding tap transformer controlled by the on-load tap changer 2 is isolated from the grid.

[0037] In Fig. 3, a second embodiment of the installation according to the invention is shown diagrammatically. The above description of the installation according to Fig. 2 applies analogously to the installation according to Fig. 3, and only the differences from the installation according to Fig. 2 will be described below. The installation 1 according to Fig. 3 comprises a interrupting element 5 and a current limiting element 7, which are configured, for example, as current limiting switching devices, as known, for example, from DE 19953551 A1. The switching device comprises an electrically driven contact system which interrupts the current flow in the first power line 4. For example, two parallel diversion paths are provided for diverting the current. In this case, the diversion path through which the current is diverted last comprises the PTC element 7. The PTC element 7 is used as a current limiting element and is configured in such a way that it can limit the short-circuit current until the higher-level protection system is tripped.

[0038] A third embodiment of the inventive installation is shown diagrammatically in Fig. 4. Fig. 4 shows in particular a representative three-dimensional arrangement of the inventive installation 1. The above description of the installation according to Fig. 4 applies analogously to the installations according to Figs. 3 and 4, and in the following only the differences and additional features will be described. The installation 1 limits short-circuit currents in the event of a fault in an on-load tap changer 2, which controls the voltage behavior of a tap transformer 20. The tap transformer 20 has a housing 23, in particular an oil tank, with a lid 24. The on-load tap changer 2 is arranged below the transformer lid 24. In this case, the selector 11 is fixed to the underside of the diverter switch 8. A first sensor 3 arranged on the power line 4 and a disconnecting element 5, which here is configured as a detonator, for example an industrial detonator, are mounted on the outer lid 20 of the transformer housing 23. The first power line 4 is connected to a winding tap N (not shown) via a winding tap N. j2, the current limiting element 7 extends from the inside to the outside of the housing 23 via a bushing 22, or from the outside to the inside, of the housing 23, and finally into the change-over switch 8. The sensor 3 and the interrupting element 5 are arranged between the bushings 22. The bushings 22 may be standard bushings for use in the range of 4 kV, for example constructed according to German Industrial Standards. A resistor 7 present in the housing 23 of the transformer is arranged in parallel to the first power line 4. Alternatively, one of the transition resistors in the change-over switch 8 may be used as the current limiting element 7 and connected in parallel to the first power line 4. A winding tap N (not shown) J+1 A second sensor 9 is arranged in a second power line 10 extending into the change-over switch 8 from a second selector contact which contacts the second selector contact 11. The second sensor 9 is therefore located in the housing 23 of the transformer. However, it is equally possible to mount the sensor 9 outside the housing 23 of the transformer, for example on the lid 24, and for this purpose to run the second power line 10 through these bushings 22 from the inside to the outside of the housing 23 or from the outside to the inside. The load current is conducted from the change-over switch 8 through another bushing 22 from the inside to the outside to the load conductor 12.

[0039] 5 shows a schematic representation of a first embodiment of a method for limiting short circuit currents. In this embodiment, an installation 1 comprises a first sensor 3, a shutoff element 5, a current limiting element 7 and a control device 6. The method comprises, for example, the successive steps 100, 200 and 500.

[0040] In step 100, the current in a first power line of an on-load tap changer is measured by a first sensor. In a next step 200, a first measurement signal indicative of the measured current in the first power line of the on-load tap changer is transmitted from the first sensor to a control device. In another next step 500, a disconnecting element arranged in the first power line of the on-load tap changer is operated by the control device to interrupt the current flow in the first power line of the on-load tap changer, and the current is diverted to a current limiting element.

[0041] In Fig. 6, a second embodiment of the method is shown diagrammatically. In this embodiment, the installation 1 further comprises a second sensor 9. In this case, the method comprises, for example, steps 100, 101, 200, 201, 300, 301 and 400. In this case, steps 100 and 200 are configured the same as steps 100 and 200 according to Fig. 5. The method according to Fig. 6 further comprises step 101, according to which, in addition to the measurement of the current in the first power line in step 100, the current in the second power line of the on-load tap changer is measured by a second sensor. In the next step 201, which follows step 101, in addition to the transmission of the first measurement signal in step 200, a second measurement signal indicative of the measured current in the second power line of the on-load tap changer is transmitted from the second sensor to the control device. Step 200 is followed by step 300, in which the first measurement signal is compared by the control device with a predefined limit value. If the first measurement signal is greater than or equal to the predetermined limit value (indicated by "yes" in FIG. 6), then the second measurement signal is likewise compared to the predetermined limit value by the control device in step 301. If the second measurement signal is also greater than or equal to the predetermined limit value (indicated by "yes" in FIG. 6), then in a next step 400 a shut-off element is operated by the control device.

[0042] If in step 300 it is determined that the first measurement signal is below the predefined limit value (indicated by "No" in FIG. 6), steps 100 and 101 are executed again. The blocking element is not operated.

[0043] If in step 301 it is determined that the second measurement signal is below the predefined limit value (indicated by "No" in FIG. 6), steps 100 and 101 are executed again. The blocking element is not operated.

[0044] Instead of the above sequence in which step 301 is followed by step 300, first the second measurement signal may be compared with the limit value and subsequently the second measurement signal may be compared with the limit value. The present application relates to the invention described in the claims, but may also include the following configurations as other aspects. 1. a first sensor (3) for measuring the current in a first power line (4) of the on-load tap changer (2); a blocking element (5), a control device (6), - a current limiting element (7), An installation (1) for limiting a short circuit current in an on-load tap changer (2), in particular in a changeover switch (8) of the on-load tap changer (2), comprising: the interruption element (5) is arranged in the first power line (4) of the on-load tap changer (2), - the current limiting element (7) is arranged in parallel with the interrupting element (5), the first sensor (3) is configured to transmit a first measurement signal (M1) indicative of the measured current in the first power line (4) of the on-load tap changer (2) to the control device (6), the installation (1), wherein the interrupting element (5) is operable by the control device (6) such that the interrupting element (5) is capable of interrupting the current flow in the first power line (4) of the on-load tap changer (2) so that the current flow is diverted to the current limiting element (7). 2. 2. The installation (1) according to claim 1, wherein the interrupting element (5) has a switching time of less than 1 millisecond for interrupting the passage of current. 3. 3. The installation (1) according to claim 1 or 2, wherein the interrupting element (5) is configured as a semiconductor element, or as a non-electrical or electric detonator, or as a mechanical contact device with an electric drive. 4. 2. The installation (1) according to claim 1, wherein the current limiting element (7) is designed for a current strength corresponding to a multiple of the rated current of the on-load tap changer (2). 5. 5. The installation (1) according to claim 4, wherein the current limiting element (7) is configured as a resistor or as an inductor, in particular as a coil. 6. 6. The installation (1) according to any one of 1 to 5 above, wherein the installation (1) comprises a second sensor (9) for measuring a current in a second power line (10) of the on-load tap changer (2), the second sensor (9) being configured to transmit a second measurement signal (M2) indicative of the measured current in the second power line (10) of the on-load tap changer (2) to the control device (6). 7. The installation (1) described in claim 6, wherein the control device (6) is configured to operate the shut-off element (5) when both the first measurement signal (M1) and the second measurement signal (M2) are above a predetermined limit value. 8. 8. The installation (1) according to claim 7, wherein the predetermined limit value is a maximum value of current which is a multiple of the rated current of the on-load tap changer (2). 9. The facility (1) according to the above-mentioned item 7, wherein the predetermined limit value is a maximum amount of change within a preset period of time. 10. -Selected winding tap (N j ) in a no-current state, and a selector (11) for preselecting the first winding tap (Nj-1 ) preselected winding taps (N j A change-over switch (8) for actually switching to the a first power line (4) electrically connecting the selector (11) and the change-over switch (8) to each other; - an installation (1) configured according to paragraph 1 above, A plurality of winding taps (N 1 ,...,N J ,...,N N ) without interruption. 11. - the on-load tap changer (2) includes a second power line (10) electrically connecting the selector (11) and the diverter switch (8) to each other, The on-load tap changer (2) according to claim 10, wherein the installation (1) comprises a second sensor (9) for measuring the current in a second power line (10), the second sensor (9) being configured to transmit to the control device (6) a second measurement signal (M2) indicative of the measured current in the second power line (10) of the on-load tap changer (2). 12. below, -100: measuring a current in a first power line (4) of the on-load tap changer (2) by a first sensor (3); -200: transmitting a first measurement signal (M1) indicative of the measured current in the first power line (4) of the on-load tap changer (2) from the first sensor (3) to a control device (6); -500: operating a disconnecting element (5) arranged in the first power line (4) of the on-load tap changer (2) such that the current in the first power line (4) of the on-load tap changer (2) is interrupted and the current is diverted to a current limiting element (7); A method for limiting a short-circuit current in an on-load tap changer (2), in particular in a diverter switch (8) of the on-load tap changer (2), comprising: 13. - in step (101), in addition to measuring the current in the first power line (4), the current in a second power line (10) of the on-load tap changer (2) is measured by a second sensor (9), - in step (201), in addition to transmitting the first measurement signal (M1), a second measurement signal (M2) indicative of the measured current in the second power line (10) of the on-load tap changer (2) is transmitted from the second sensor (9) to the control device (6), - in step (300), said first measurement signal (M1) is compared by said control device (6) with a predetermined limit value, - in step (301), said second measurement signal (M2) is compared by said control device (6) with a predetermined limit value, 13. The method according to claim 12, wherein in step (400), the blocking element (5) is operated if both the first measurement signal (M1) and the second measurement signal (M2) are greater than or equal to a predefined limit value. [Explanation of symbols]

[0045] 1 equipment 2 On-load tap changer 3 First Sensor 4. First Power Line 5. Blocking Elements 6. Control device 7 Current-limiting element 8 Switch switch 9 Second Sensor 10 Second Power Line 11 Selector 12 Load conductor 13 Signal connection wire 14 Current Path 20 tap transformer 21 Control Winding 22 Bushing 23 Tap Transformer Housing 24 Tap Transformer Cover 25 Main Winding (N1,...,N J ,...,N N ) Winding tap M1,M2 measurement signal 100 Method Steps 101 Method Steps 200 Method Steps 201 Method Steps 300 Method Steps 301 Method Steps 400 Method Steps 500 method steps

Claims

1. a first sensor (3) for measuring the current in a first power line (4) of the on-load tap changer (2); - a blocking element (5), a control device (6), - a current limiting element (7), An installation (1) for limiting a short circuit current in the on-load tap changer (2) or in a changeover switch (8) of the on-load tap changer (2), comprising: the interruption element (5) is arranged in the first power line (4) of the on-load tap changer (2), - the current limiting element (7) is arranged in parallel to the interrupting element (5), the first sensor (3) is configured to transmit a first measurement signal (M1) indicative of the measured current in the first power line (4) of the on-load tap changer (2) to the control device (6), the interruption element (5) is operable by the control device (6) such that the interruption element (5) is capable of interrupting the passage of current in the first power line (4) of the on-load tap changer (2) such that the conducted current is diverted to the current limiting element (7); The installation (1) comprises a second sensor (9) for measuring a current in a second power line (10) of the on-load tap changer (2), the second sensor (9) being configured to transmit a second measurement signal (M2) indicative of the measured current in the second power line (10) of the on-load tap changer (2) to the control device (6), The control device (6) is configured to operate the shut-off element (5) when both the first measurement signal (M1) and the second measurement signal (M2) are above a predetermined limit value.

2. 2. The installation (1) according to claim 1, wherein the interrupting element (5) has a switching time of less than 1 millisecond for interrupting the current flow.

3. 3. The installation (1) according to claim 1 or 2, wherein the interrupting element (5) is configured as a semiconductor element, or as a non-electrical or electric detonator, or as a mechanical contact device with an electric drive.

4. 2. The installation (1) according to claim 1, wherein the current limiting element (7) is designed for a current strength corresponding to a multiple of the rated current of the on-load tap changer (2).

5. 5. The installation (1) according to claim 4, characterized in that the current limiting element (7) is configured as a resistor or as an inductor or as a coil.

6. 2. The installation (1) according to claim 1, wherein the predetermined limit value is a maximum value of current which is a multiple of the rated current of the on-load tap changer (2).

7. 2. The installation (1) according to claim 1, wherein the predetermined limit value is a maximum change within a preset period of time.

8. - Selected winding tap (N ｊ ) in a no-current state, and a selector (11) for preselecting the first winding tap (N ｊ－１ ) preselected winding taps (N ｊ A change-over switch (8) for actually switching to the - a first power line (4) and a second power line (10) electrically connecting said selector (11) and said change-over switch (8) to each other; - an installation (1) constructed according to claim 1, A plurality of winding taps (N １ , . . . , N Ｊ , . . . , N Ｎ ) without interruption.

9. below, -100: measuring the current in a first power line (4) of the on-load tap changer (2) by a first sensor (3); -200: transmitting a first measurement signal (M1) indicative of the measured current in the first power line (4) of the on-load tap changer (2) from the first sensor (3) to a control device (6); -500: operating a disconnecting element (5) arranged in the first power line (4) of the on-load tap changer (2) such that the current in the first power line (4) of the on-load tap changer (2) is interrupted and the current is diverted to a current limiting element (7); A method for limiting a short circuit current in an on-load tap changer (2) or in a changeover switch (8) of an on-load tap changer (2) configured according to claim 8 and having an installation (1) configured according to any one of claims 1 to 7, comprising:

10. - in step (101), in addition to measuring the current in said first power line (4), the current in a second power line (10) of said on-load tap changer (2) is measured by a second sensor (9), - in step (201), in addition to transmitting the first measurement signal (M1), a second measurement signal (M2) representative of the measured current in the second power line (10) of the on-load tap changer (2) is transmitted from the second sensor (9) to the control device (6), - in step (300), said first measurement signal (M1) is compared by said control device (6) with predefined limit values, - in step (301), said second measurement signal (M2) is compared by said control device (6) with a predefined limit value, 10. The method according to claim 9, wherein in step (400), the shut-off element (5) is actuated if both the first measurement signal (M1) and the second measurement signal (M2) are greater than or equal to a predefined limit value.

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