Device for limiting short-circuit currents in on-load tap changers and on-load tap changer with said device

Abstract

The invention relates to a device for limiting short-circuit currents in a load tap changer, in particular in a load transfer switch of a load tap changer, comprising a first sensor for measuring a current in a first current line of the load tap changer, an interrupting element, a control device and a current limiting element, wherein the interrupting element is arranged in the first current line of the load tap changer, the current limiting element is arranged in parallel to the interrupting element, the first sensor is configured to transmit a first measurement signal M1 representing the measured current in the first current line of the load tap changer to the control device, the interrupting element can be actuated by the control device such that the interrupting element can interrupt the current guidance in the first current line of the load tap changer, thereby diverting the guided current onto the current limiting element.

Description

Technical Field

[0001] The present invention relates to a device for limiting short-circuit current in an on-load tap changer, particularly an on-load transfer switch of an on-load tap changer, and an on-load tap changer including a device for limiting short-circuit current in the on-load tap changer. Background Technology

[0002] On-load tap changers are known to be used for uninterrupted switching between different taps of the regulating winding of a tap changer, and thereby for voltage regulation. An on-load tap changer typically consists of a selector and an on-load transfer switch. The selector is used for no-power pre-selection of the tap to which the tap changer should be switched, and the transfer switch is used for actual uninterrupted switching from the currently connected tap to the new pre-selected tap. For no-power pre-selection of the tap, the selector typically has two movable selector contacts that connect the tap. The on-load transfer switch for actual load switching typically has switch contacts and a resistor. The switch contacts are arranged in the main load branch of the on-load transfer switch and are used to directly connect the tap connected by the corresponding selector contact to the load lead via the main load branch. The resistor is used to limit the circulating current flowing in the on-load transfer switch for short periods during the switching process and is also called a transition resistor.

[0003] Non-compliant operation of the on-load tap changer can lead to functional failure. One possible functional failure is a short circuit in the on-load tap changer, more precisely, a short circuit in the on-load transfer switch, triggered by arcing between the two main load branches. Since the two main load branches are electrically connected to the regulating winding taps via selector contacts, this results in a tap short circuit. Specifically, this means that short-circuit current flows through the main load branches and the selector contacts, passing through the regulating stage of the tap changer's regulating winding.

[0004] To protect transformers from significant damage or destruction in the event of a short circuit, power switches are installed in the transmission network. These power switches are designed to reliably interrupt high currents in the event of a fault. However, this requires a relatively long time, such as 50 ms. During this duration, the short-circuit current flows unrestricted through the conductive components of the tap changer and the transformer, which can lead to significant damage to the on-load tap changer and the regulating winding of the transformer. This is to be avoided. Summary of the Invention

[0005] Against this backdrop, the present invention proposes a device for limiting short-circuit current in an on-load tap changer, an on-load tap changer for uninterrupted switching between the taps of the windings of a tap changer transformer, and a method for limiting short-circuit current in an on-load tap changer, according to the present invention.

[0006] The improved solution is based on the idea of ​​providing a device that can identify a short circuit in the on-load transfer switch of an on-load tap changer quickly enough and also commutate the rising short-circuit current to a resistor before reaching a critical value. The resistor limits the current to an allowable value until an upstream protection system, such as a power switch, is triggered and disconnects the transformer from the transmission network.

[0007] According to a first aspect, the present invention provides a device for limiting short-circuit current in an on-load tap changer, particularly in an on-load transfer switch of an on-load tap changer. The device includes a first sensor for measuring current in a first current line of the on-load tap changer, an interrupting element, a control device, and a current limiting element. The interrupting element is arranged in the first current line of the on-load tap changer. The current limiting element is arranged in a parallel path connected in parallel with the interrupting element, i.e., in parallel with the first current line. The first sensor is configured to transmit a first measurement signal to the control device, the first measurement signal representing the measured current in the first current line of the on-load tap changer. The current measurement and the transmission of the measurement signal can be performed continuously or uninterrupted in time, preferably at a sampling rate of less than one microsecond. The transmission of the measurement signal to the control unit can be achieved via radio, via an optical waveguide, or preferably via a wire, particularly preferably via a shielded wire.

[0008] The sensor is preferably constructed as a current transformer. However, in principle, any type of sensor capable of continuously measuring the time-varying curve of the current in the line and further transmitting it to the control unit in the form of a measurement signal can be used to implement the solution according to the invention.

[0009] The control device is preferably configured to detect and / or obtain a time-varying curve of a measurement signal representing the measured current.

[0010] The first sensor can be preferably located outside the housing of the corresponding transformer (the voltage of which is regulated by an on-load tap changer), on the cover of the transformer housing, or inside the transformer housing.

[0011] The interrupting element can be manipulated by the control device to interrupt the current flow in the first current line of the on-load tap changer, so that the current flow in the first current line is diverted to, i.e., transmitted to, a parallel path connected in parallel with the current limiting element and limited by the current limiting element.

[0012] According to an advantageous embodiment, the first current line electrically connects the selector, preferably the first movable selector contact, and the first main load branch of the on-load transfer switch, preferably the on-load tap changer, to each other.

[0013] According to the implementation method, the interrupting element is arranged in a section of the first current line, which is outside the on-load tap changer, that is, outside the selector and the on-load transfer switch.

[0014] According to another embodiment, the interrupting element has a switching time of less than 1.0 ms, preferably less than 0.5 ms, and particularly preferably less than 0.1 ms for interrupting current guidance. Due to the short response time of the interrupting element, the rising short-circuit current is switched to the current limiting element before the short-circuit current reaches a critical value.

[0015] Interruption elements can be placed outside the transformer housing, preferably on the cover, or inside the transformer housing.

[0016] According to another embodiment, the interrupting element is configured as a semiconductor switching element, or as an explosive or dynamite, or as a mechanical contact assembly with an electric actuator.

[0017] Semiconductor switching elements can be configured as IGBTs and / or thyristors, for example. Explosives or explosives used to separate electrical connections, such as cables or rails, are well known in the prior art. Suitable separation devices are, in particular, cutting fillers or detonators, such as those described in EP 0052521 A1, for example, in medium-voltage applications, such as the so-called "I..." s The term "limiter" has been used for decades. Mechanical contact components with electric actuators can be constructed, for example, in the form of a contact ring system as described in DE 199 53 551 C1, and can also be possible devices for interrupting current flow in the first current line.

[0018] All these interrupt elements have the advantage of having extremely short switching or manipulation times in the range of 0.1 to 1.0 ms.

[0019] According to a preferred embodiment, the current limiting element is designed to a current intensity corresponding to a multiple of the rated current, for example, twice the rated current of an on-load tap changer. The rated current, also referred to in relevant standards as the rated current-through current, is the rated current of an on-load tap changer in continuous operation. Accordingly, according to this preferred embodiment of the invention, the current limiting element of an on-load tap changer having a rated current of 800 A is designed such that the element can temporarily limit the short-circuit current to 1600 A, for example, within a time period of 50 ms.

[0020] The current limiting element can be constructed as a resistor, such as an ohmic resistor, a cold conductor, a fuse with a fusible conductor, or as an inductor, especially as a coil. Preferably, as a resistor for the device, one of the transition resistors in the on-load transfer switch of the on-load tap changer can be connected in parallel with the first current line.

[0021] According to a preferred embodiment, the device for limiting the current includes, in addition to the first sensor, a second sensor for measuring the current in the second current line of the on-load tap changer. The second sensor is configured to transmit a second measurement signal to the control device, the second measurement signal representing the measured current in the second current line of the on-load tap changer. The second current line preferably electrically connects a selector, preferably a second movable selector contact, to the on-load transfer switch, preferably a second main load branch of the on-load transfer switch. The second sensor is preferably constructed similarly to the first sensor, and the second measurement signal is preferably constructed similarly to the first measurement signal. The second sensor can be arranged outside the transformer housing, particularly on a cover, or inside the transformer housing.

[0022] According to the embodiment, the control device is configured to operate the interruption element when both the first measurement signal and the second measurement signal are greater than or equal to a predetermined limit value.

[0023] The control device determines, based on the first and second measurement signals, whether the measured current in the first current line and the measured current in the second current line have both reached or exceeded the limit value, and if so, manipulates the interrupting element.

[0024] According to an embodiment of the invention, the specified limit value is the maximum current value, which is several times the rated current of the on-load tap changer. Therefore, according to this embodiment of the invention, in an on-load tap changer having a rated current of, for example, 800 A, the limit value is determined to be a maximum current value of 1600 A. This specifically means that when a current of at least 1600 A is measured not only in the first current line but also in the second current line, the interrupting element is operated by the control device.

[0025] According to another embodiment, the specified limit value is the maximum change in current within a predetermined time period. For example, according to this embodiment, in an on-load tap changer designed with a rated current of 800 A, the limit value is 1.2 A / μs. This specifically means that when the current measured in the first and second current lines increases by 1.2 A or more within one microsecond, the interrupting element is actuated by the control device. This has the advantage that any short-circuit current that occurs can be identified more quickly, for example, within one microsecond, because the abnormally rapid increase in current is detected earlier by the sensors and control device.

[0026] According to a second aspect, the present invention provides an on-load tap changer for uninterrupted switching between winding taps of a tap changer transformer. The on-load tap changer includes a selector for pre-selecting a selected winding tap without power, an on-load transfer switch for actual load switching from the current winding tap to the pre-selected winding tap, and a first current line electrically connecting the selector to the on-load transfer switch, preferably a first selector arm, and a first main load branch. Furthermore, the on-load tap changer according to the invention includes means for limiting short-circuit current in the on-load tap changer, particularly in the on-load transfer switch of the on-load tap changer, which is constructed according to the first aspect of the invention. Regarding the means, reference is made to the foregoing description, preferred features, and / or advantages in a manner similar to that already set forth with respect to the first aspect of the invention or an advantageous embodiment thereof.

[0027] According to a preferred embodiment, the on-load tap changer includes a second current line that electrically connects the selector to the on-load transfer switch, preferably a second selector arm, and a second main load branch. Furthermore, in this embodiment, the device includes a second sensor for measuring the current in the second current line. The second sensor is configured to transmit a second measurement signal to the control device, the second measurement signal representing the measured current in the second current line of the on-load tap changer.

[0028] According to a third aspect, the present invention proposes a method for limiting short-circuit current in an on-load tap changer, particularly in an on-load transfer switch of an on-load tap changer, wherein the on-load tap changer is constructed according to a second aspect of the invention and includes devices constructed according to a first aspect of the invention. The method comprises the following steps: measuring the current in a first current line of the on-load tap changer using a first sensor; transmitting a first measurement signal from the first sensor to a control device, the first measurement signal representing the measured current in the first current line of the on-load tap changer; and actuating an interrupting element arranged in the first current line of the on-load tap changer such that current guidance in the first current 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 with the interrupting element, particularly in a current path parallel to the first current line.

[0029] The steps of this method correspond to the features of the device according to the first aspect of the invention and the features of the on-load tap changer according to the second aspect of the invention. Therefore, for the method according to the third aspect of the invention, reference is made to advantageous descriptions, preferred features, and / or advantages in a manner similar to that already described for the device and on-load tap changer according to the second and third aspects of the invention.

[0030] According to a preferred embodiment of the method, the method includes additional steps, according to which, in addition to measuring the current in the first current line, the current in the second current line of the on-load tap changer is measured by means of a second sensor; in addition to transmitting the first measurement signal, a second measurement signal is transmitted from the second sensor to the control device, the second measurement signal representing the measured current in the second current line of the on-load tap changer; furthermore, the first and second measurement signals are compared with predetermined limit values ​​by means of the control device, and the interrupting element is actuated when both the first and second measurement signals are greater than or equal to the predetermined limit values. This preferred embodiment of the method is described with reference to a similar manner to that described for corresponding advantageous designs of the device, highlighting preferred features and / or advantages.

[0031] Other design and implementation methods of this method are directly derived from different design methods of the device.

[0032] The invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments. Here, all described and / or illustrated features, in themselves and in any combination, form the subject matter of the invention. Identical or functionally identical or having the same effect components may be provided with the same reference numerals. Identical components or components having the same function may be explained only with reference to the drawings in which they first appear. This explanation is not necessarily repeated in subsequent drawings. Attached Figure Description

[0033] Here it is shown: Figure 1 An exemplary embodiment of an on-load tap changer is illustrated schematically. Figure 2 A first embodiment of the device is illustrated in schematic diagram; Figure 3 A second embodiment of the device is illustrated in schematic diagram; Figure 4 A third embodiment of the device is illustrated in the schematic diagram; Figure 5 A first embodiment of a method for limiting short-circuit current is illustrated in schematic diagram; Figure 6 A second embodiment of the method is illustrated in the diagram. Detailed Implementation

[0034] exist Figure 1 The diagram schematically illustrates an exemplary embodiment of an on-load tap changer 2 for a tap transformer 20. The tap transformer 20 has a main winding 25 and taps N1, ..., N2 with different winding taps. J ..., NN The regulating winding 21 has its taps connected or disconnected via an on-load tap changer 2. For this purpose, the on-load tap changer 2 includes a selector 11 and an on-load changeover switch 8. The selector, via two movable selector contacts, can contact different winding taps N1, ..., N2 of the regulating winding 21. J ..., N N The on-load transfer switch performs the actual load transfer from the currently connected winding tap to a new pre-selected winding tap. Figure 1 In the position of the on-load transfer switch 8 shown, the load current flows from the currently connected winding tap N. J+1 The current flows to the load lead 12 through the corresponding selector contacts and on-load transfer switch 8.

[0035] exist Figure 2 The diagram illustrates a first embodiment of the device according to the invention. Device 1 is used to limit short-circuit current in the event of a fault in the on-load tap changer 2, particularly the on-load transfer switch 8. The on-load transfer switch 8 has multiple switching contacts and resistors for switching. However, the specific circuit arrangement of the on-load transfer switch is not important for the implementation of the invention, and therefore will not be discussed in more detail. The on-load tap changer 2 includes a selector 11 with two movable selector arms, which respectively contact the winding tap N of the regulating winding of a tap changer transformer (not shown). J N J+1Device 1 includes a first sensor 3 arranged in a first current line 4 and a second sensor 9 arranged in a second current line 10. Sensors 3 and 9 are used to continuously measure the current flowing through the respective current lines 4 and 10 and to continuously transmit the measured current to control device 6 in the form of measurement signals M1 and M2. Sensors 3 and 9 can transmit measurement signals M1 and M2 to control device 6, for example, via signal connection 13. The first current line 4 connects the movable first selector contact of selector 11 to the on-load transfer switch 8 of on-load tap changer 2. Similarly, the second current line 10 connects the movable second selector contact of selector 11 to the on-load transfer switch 8. An interrupting element 5 is arranged in the first current line 4, which is configured as an IBGT switch 5 according to the first embodiment and is designed and operated such that the interrupting element can switch the short-circuit current that occurs in the event of a fault in the on-load transfer switch 8. The semiconductor switching element 5 is operated by control device 6 when not only the first measurement signal M1 but also the second measurement signal M2 is greater than or equal to a predetermined limit value. The current flow in the first current line 4 is then interrupted by the semiconductor switching element 5, causing the current to be diverted to the current limiting element 7. The current limiting element 7 is here configured, for example, as an ohmic resistor and arranged in parallel with the semiconductor switching element 5 or in the current path 14 in parallel with the first current line 4, and is designed such that the element can limit the rising short-circuit current for such a long time that an upstream protection system, such as a power switch, is actuated and the associated tap transformer, regulated by the on-load tap changer 2, is disconnected from the transmission network.

[0036] exist Figure 3 The diagram illustrates a second embodiment of the device according to the invention. Regarding... Figure 3 Device 1 in the middle is referenced in a similar manner to the device 1 in the middle. Figure 2 The previous explanation of the device in the text and the following discussion only involve... Figure 2 The differences between the devices. Figure 3 Device 1 has an interrupting element 5 and a current limiting element 7, which are constructed, for example, in the form of a current-limiting switching unit, as known for example from DE 199 53 551 C1. The switching unit includes a contact ring system with an electric actuator that interrupts current flow in the first current line 4 in the event of a short circuit. For current commutation, two parallel commutation paths are provided, wherein the commutation path to which the current is finally commutated has a PTC element 7, which functions as a current limiting element and is constructed such that it can limit the short-circuit current until an upstream protection system is activated.

[0037] exist Figure 4 The diagram illustrates a third embodiment of the device according to the invention. Figure 4An exemplary spatial arrangement of the device 1 according to the invention is shown in particular. Regarding... Figure 4 Device 1 in the middle is referenced in a similar manner to the device 1 in the middle. Figure 3 and Figure 4 The previous description of device 1 will now only discuss the differences and supplementary features. In the event of a failure of the on-load tap changer 2, device 1 limits the short-circuit current, which regulates the voltage ratio of the tap changer 20. The tap changer 20 has a housing 23 with a cover 24, particularly the tank. The on-load tap changer 2 is arranged below the cover 24 of the transformer, wherein the selector 11 is spatially located below the on-load transfer switch 8. The first sensor 3, arranged in the first current line 4, and the interrupting element 5 are mounted on the cover 24 outside the transformer housing 23. The interrupting element is exemplarily constructed here as an explosive in the form of a detonator. The first current line 4 starts from the contact winding tap N. J The first selector contact (not shown) is guided from the inside of the housing 23 outwards or from the outside inwards via a through-hole 22, and finally into the on-load transfer switch 8. The sensor 3 and the interrupting element 5 are arranged between the through-holes 22. The through-holes 22 can be, for example, standard through-holes constructed according to DIN standards for applications in the 4 kV range. A resistor 7 is arranged in parallel with the first current line 4, located within the transformer housing 23. Alternatively, one of the transition resistors in the on-load transfer switch 8 can also serve as the current limiting element 7 and be connected in parallel with the first current line 4. A second sensor 9 is arranged in the second current line 10 in the section outside the on-load transfer switch 8 and the selector 11, the second current line being connected by a contact winding tap N. J +1 The second selector contact (not shown) leads to the on-load transfer switch 8. The second sensor 9 is therefore located inside the transformer housing 23. However, it is also possible to mount the sensor 9 outside the transformer housing 23, for example, on the cover 24, and the second current line 10 is thus guided from the inside to the outside or from the outside to the inside of the housing 23 via the through-hole 22. The load current is transmitted from the on-load transfer switch 8 from the inside to the outside via another through-hole 22 to the load lead 12.

[0038] exist Figure 5 The diagram illustrates a first embodiment of a method for limiting short-circuit current. In this embodiment, device 1 includes a first sensor 3, an interrupting element 5, a current limiting element 7, and a control device 6. The method exemplarily has steps 100, 200, and 500 that are sequentially arranged.

[0039] In step 100, the current in the first current line of the on-load tap changer is measured using a first sensor. In the next step 200, a first measurement signal representing the measured current in the first current line of the on-load tap changer is transmitted from the first sensor to the control device. In a further subsequent step 500, an interrupting element arranged in the first current line of the on-load tap changer is manipulated by the control device to interrupt the current flow in the first current line of the on-load tap changer and redirect the current to a current limiting element.

[0040] exist Figure 6 A second embodiment of the method is schematically illustrated. In this embodiment, device 1 additionally includes a second sensor 9. The method exemplarily includes steps 100, 101, 200, 201, 300, 301, and 400, wherein steps 100 and 200 are related to... Figure 5 Steps 100 and 200 are constructed in the same way. Figure 6 The method additionally includes step 101, according to which, in addition to measuring the current in the first current line in step 100, the current in the second current line of the on-load tap changer is measured by means of a second sensor. In step 201, following step 101, in addition to the transmission of the first measurement signal in step 200, a second measurement signal, representing the measured current in the second current line of the on-load tap changer, is transmitted from the second sensor to the control device. In a further step 300 following step 200, the first measurement signal is compared with a predetermined limit value by means of the control device. When the first measurement signal is equal to or greater than the predetermined limit value ( Figure 6 (Indicated by "Yes"), in step 301, the second measurement signal is also compared with a predetermined limit value using a control device. When the second measurement signal is also greater than or equal to the predetermined limit value (in... Figure 6 (In the next step 400, the interrupt element is manipulated by the control device, indicated by "Yes").

[0041] In step 300, when it is determined that the first measurement signal is below a specified limit value (in... Figure 6 If the condition is indicated by "No", then steps 100 and 101 are repeated. The interrupt element is not manipulated.

[0042] In step 301, when it is determined that the second measurement signal is below a specified limit value (in... Figure 6 If the condition is indicated by "No", then steps 100 and 101 are repeated. The interrupt element is not manipulated.

[0043] As an alternative to step 301 being performed after step 300, the second measurement signal may be compared with the limit value first, and then the first measurement signal may be compared with the limit value.

[0044] List of reference numerals

[0045] 1 Equipment

[0046] 2 On-load tap changer

[0047] 3 First Sensor

[0048] 4 First Current Circuit

[0049] 5 Interrupt Components

[0050] 6. Control device

[0051] 7 Current limiting element

[0052] 8 On-load transfer switch

[0053] 9 Second sensor

[0054] 10 Second Current Circuit

[0055] 11 Selector

[0056] 12 Load Leads

[0057] 13 Signal Connection

[0058] 14 Current Path

[0059] 20 tap changer

[0060] 21 Adjusting winding

[0061] 22 Pass-through part

[0062] 23 The shell of 20

[0063] 24 The cover of 20

[0064] 25 Main winding

[0065] (N1, ..., N) J ..., N N Winding taps

[0066] M1, M2 measurement signals

[0067] 100 Methods and Steps

[0068] 101 Methods and Steps

[0069] 200 Methods and Steps

[0070] 201 Method and Steps

[0071] 300 Methods and Steps

[0072] 301 Method and Steps

[0073] 400 Methods and Steps

[0074] 500 Methods and Steps

Claims

1. A device (1) for limiting short-circuit current in an on-load tap changer (2), the device comprising: - A first sensor (3) for measuring the current in the first current line (4) of the on-load tap changer (2). - Interrupt element (5) - Control device (6), and - Current limiting element (7) in, - The interrupting element (5) is arranged in the first current line (4) of the on-load tap changer (2). - The current limiting element (7) and the interrupting element (5) are arranged in parallel. - The first sensor (3) is configured to transmit a first measurement signal M1 to the control device (6), the first measurement signal representing the measured current in the first current line (4) of the on-load tap changer (2). - The interrupting element (5) can be manipulated by the control device (6) so that the interrupting element can interrupt the current conduction in the first current line (4) of the on-load tap changer (2), thereby diverting the conducted current to the current limiting element (7). in, The device (1) has a second sensor (9) for measuring the current in the second current line (10), the second sensor being configured to transmit a second measurement signal M2 to the control device (6), the second measurement signal representing the measured current in the second current line (10). Its features are, - The control device (6) is configured to operate the interruption element (5) when both the first measurement signal M1 and the second measurement signal M2 are greater than or equal to a predetermined limit value.

2. The device (1) according to claim 1, wherein, The device is used to limit the short-circuit current in the on-load transfer switch (8) of the on-load tap changer (2).

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

4. The device (1) according to any one of claims 1 to 3, wherein, The interrupting element (5) is configured as a semiconductor switching element, or the interrupting element is configured as an explosive or dynamite, or the interrupting element is configured as a mechanical contact assembly with an electric actuator.

5. The device (1) according to claim 1, wherein, The current limiting element (7) is designed to have a current intensity that is multiple times the rated current of the on-load tap changer (2).

6. The device (1) according to claim 5, wherein, The current limiting element (7) is constructed as a resistor, or the current limiting element is constructed as an inductor.

7. The device (1) according to claim 6, wherein, The current limiting element is constructed as a coil.

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

9. The device (1) according to claim 1, wherein, The specified limit value is the maximum change in current within a predetermined time period.

10. A method for tapping the windings (N1, ... N) of a tap transformer (20). J ..., N N An on-load tap changer (2) that allows for uninterrupted switching between different on-load taps, the on-load tap changer comprising: - Selector (11) for powerless pre-selection to the selected winding tap (N J )superior, - On-load transfer switch (8) for switching from the current winding tap (N) J-1 ) to the pre-selected winding tap (N) J Actual load switching - A first current line (4) and a second current line (10) electrically connect the selector (11) and the on-load transfer switch (8) to each other. - The device (1) according to claim 1.

11. A method for limiting short-circuit current in an on-load tap changer (2), said on-load tap changer being the on-load tap changer according to claim 10, and said on-load tap changer comprising the device (1) according to any one of claims 1 to 9, said method comprising the following steps: - 100: The current in the first current line (4) of the on-load tap changer (2) is measured by means of the first sensor (3). - 200: Transmit the first measurement signal M1 from the first sensor (3) to the control device (6), the first measurement signal representing the measured current in the first current line (4) of the on-load tap changer (2), - 500: Manipulate the interrupting element (5) arranged in the first current line (4) of the on-load tap changer (2) to interrupt the current flow in the first current line (4) of the on-load tap changer (2) and to switch the current to the current limiting element (7).

12. The method according to claim 11, wherein, The method is used to limit the short-circuit current in the on-load transfer switch (8) of the on-load tap changer (2).

13. The method according to claim 11 or 12, wherein, - In step (101), in addition to measuring the current in the first current line (4), the current in the second current line (10) of the on-load tap changer (2) is also measured by means of the second sensor (9). - In step (201), in addition to transmitting the first measurement signal M1, the second sensor (9) also transmits a second measurement signal M2 to the control device (6). The second measurement signal represents the measured current in the second current line (10) of the on-load tap changer (2). - In step (300), the first measurement signal M1 is compared with a predetermined limit value by means of the control device (6). - In step (301), the second measurement signal M2 is compared with a predetermined limit value by means of the control device (6). - In step (400), when both the first measurement signal M1 and the second measurement signal M2 are greater than or equal to the specified limit value, the interruption element (5) is manipulated.

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