CN115443514A - Device for limiting short-circuit current in an on-load tap changer and on-load tap changer with said device - Google Patents

Abstract

The invention relates to a device (1) for limiting short-circuit currents in an on-load tap-changer (2), in particular in an on-load change-over switch (8) of the on-load tap-changer (2), comprising A first sensor (3), an interruption element (5), a control device (6) and a current limiting element (7) for measuring the current in the first current line (4) of the on-load tap-changer (2), wherein , the interrupting element (5) is arranged in the first current 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 In order to transmit the first measurement signal M representing the current measured in the first current line (4) of the on-load tap-changer (2) to the control device (6), the interruption element (5) can be passed through the control device (6 ) is actuated such that the interrupting element can interrupt the current conduction in the first current line (4) of the on-load tap changer (2), so that the conducted current is commutated to the current limiting element (7).

Description

Devices for limiting short-circuit currents in on-load tap-changers and devices with said on-load tap-changer

technical field

The invention relates to a device for limiting short-circuit currents in on-load tap-changers, in particular in on-load change-over switches of on-load tap-changers, and to an on-load tap-changer comprising Device for limiting short-circuit current in on-load tap-changers.

Background technique

On-load tap-changers are used in a known manner for uninterrupted switching between different winding taps of a control winding of a tap-changing transformer and thus for voltage regulation. An on-load tap-changer usually consists of a selector for power-free preselection of the winding tap of the tap-changer to be switched to, and an on-load change-over switch for practically uninterrupted switching from The previously connected winding tap is switched to the new preselected winding tap. For powerless preselection of winding taps, the selector usually has two movable selector contacts, which switch the winding taps. On-load transfer switches typically have switch contacts and resistors for the actual load transfer. The switching contacts are arranged in the main load branch of the on-load changeover switch and serve to directly connect the winding taps contacted by the corresponding selector with the load leads via the main load branch. The resistor serves to limit the circulating current that briefly flows in the on-load changeover switch during the switching process and is also referred to as a transition resistor.

Inappropriate operation of the on-load tap-changer can lead to malfunctions of the on-load change-over switch. One possible malfunction is a short circuit in the on-load tap-changer, more precisely in the on-load transfer switch, triggered by an arc between the two main load branches. Since the two main load branches are each electrically connected via a selector contact to a winding tap of the regulating winding, this leads to a tap short circuit. Specifically, this means that the short-circuit current flows via the regulating stage of the regulating winding of the tap transformer via the main load branch and the selector contacts.

In order to protect transformers against greater damage or destruction in the event of a short circuit, power switches are provided in the transmission network which are designed to reliably switch off high currents in the event of a fault. For this, however, they require a relatively long time, for example 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 considerable damage to the regulating winding of the on-load tap changer and the transformer. This is to be avoided.

Contents of the invention

Against this background, the present invention presents the subject-matter of the independent claims. Advantageous embodiments of the invention are described in the dependent claims.

The improved solution is based on the idea of providing a device which, in the event of a short circuit in an on-load changeover switch of an on-load tap-changer, detects the short circuit sufficiently quickly and also switches the rising The short-circuit current is commutated to a resistor, which limits the current to a permissible value until a higher-level protection system, such as a power switch, triggers and separates the transformer from the transmission network.

According to a first aspect, the invention proposes a device for limiting short-circuit currents in an on-load tap changer, in particular in an on-load changeover switch of the on-load tap changer. The device has a first sensor for measuring the current in a first current line of the on-load tap changer, an interruption element, a control device and a current limiting element. The interruption element is arranged in the first current line of the on-load tap-changer. The current limiting element is arranged in a parallel path parallel to the interrupting element, ie parallel to the first current line. The first sensor is designed 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 take place continuously or without interruption in time, preferably with a sampling rate of less than one microsecond. The transmission of the measurement signal to the control unit can take place via radio, via an optical waveguide or preferably via a line, particularly preferably via a shielded line.

The sensors are preferably designed as current transformers. In principle, however, any type of sensor which is able to continuously measure the temporal profile of the current in the line and transmit it further to the control unit in the form of a measurement signal can be used to implement the solution according to the invention.

The control device is preferably designed to detect and/or determine the temporal profile of the measurement signal representing the measured current.

The first sensor can be arranged outside the housing of the respective transformer whose voltage is regulated via the on-load tap changer, preferably on a cover of the transformer housing or inside the transformer housing.

The interrupting element can be actuated by the control device in such a way that the interrupting element can interrupt the conduction of current in the first current line of the on-load tap-changer, so that the current conducted in the first current line is commutated, ie passed on, to a parallel path parallel to the current limiting element and is limited by the current limiting element.

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 changeover switch, preferably the on-load tap changer, to one another.

According to an embodiment, the interrupting element is arranged in a section of the first current line which is outside the on-load tap changer, ie outside the selector and the on-load change-over switch.

According to a further embodiment, the interruption element has a switching time for interruption of the current conduction of less than 1.0 ms, preferably of less than 0.5 ms and particularly preferably of less than 0.1 ms. Due to the short reaction time of the interrupting element, the rising short-circuit current is commutated to the current-limiting element before the short-circuit current reaches a critical value.

The interruption element can be arranged outside the transformer housing, preferably on the cover, or inside the transformer housing.

According to further embodiments, the interruption element is designed as a semiconductor switching element or as an explosive or explosive charge or as a mechanical contact assembly with an electric drive.

The semiconductor switching elements can be designed, for example, as IGBTs and/or thyristors. Explosives or explosives for separating electrical connections, such as cables or rails, are sufficiently known from the prior art. Suitable separation devices are in particular pyrotechnic cutting charges or detonators such as those described in EP 0052521 A1, as they have been used for decades in medium-voltage applications, for example in so-called "I _s limiters". A mechanical contact assembly with an electric drive can be designed, for example, as described in DE 199 53 551 C1 in the form of a contact ring system and can likewise be a possible device for interrupting the current conduction in the first current line.

All these interrupt elements have the advantage that they have extremely short switching or actuation times in the range of 0.1 to 1.0 ms.

According to a preferred embodiment, the current limiting element is designed for a current strength which corresponds to a multiple of the rated current, for example twice the rated current of the on-load tap changer. The rated current, also called the rated through current in the relevant standards, is the rated current of the on-load tap-changer in continuous operation. Accordingly, according to this preferred embodiment of the invention, the current limiting element of the on-load tap-changer with a rated current of 800 A is designed such that the element can be switched off briefly, for example within a period of 50 ms. The short circuit current is limited to 1600A.

The current limiting element can be designed as a resistor, for example an ohmic resistor, a cold conductor, a fuse with a fusible conductor or as an inductor, in particular as a coil. Preferably, one of the transition resistors in the on-load changeover switch of the on-load tap changer can also be connected in parallel to the first current line as a resistor for the device.

According to a preferred embodiment, the device for limiting the current comprises, in addition to the first sensor, a second sensor for measuring the current in a second current line of the on-load tap-changer. The second sensor is designed 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 the selector, preferably the second movable selector contact, and the on-load changeover switch, preferably the second main load branch of the on-load changeover switch, to one another. 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 transformer housing, in particular on the cover, or inside the transformer housing.

According to an embodiment, the control device is configured to actuate the interrupt element when both the first and the second measurement signal are greater than or equal to a defined limit value.

The control device determines on the basis of the first measurement signal and the second measurement signal whether the measured current in the first current line and the measured current in the second current line have both reached or exceeded a limit value, and if this is the case, The interrupt element is then actuated.

According to an embodiment of the invention, the prescribed limit value is a maximum value of the current which is a multiple of the rated current of the on-load tap-changer. Therefore, according to this embodiment of the invention, in an on-load tap-changer with a rated current of eg 800A, the limit value is determined as a current maximum value of 1600A. This means in particular that the interruption element is actuated by the control device when a current of at least 1600 A is measured both in the first current line and in the second current line.

According to a further embodiment, the prescribed limit value is the maximum change in current within a predetermined time period. For example, in an on-load tap-changer designed for a rated current of 800 A according to this embodiment, the limit value is 1.2 A/μs. This means in particular that the interruption element is actuated by the control device when the measured currents in the first and second current lines increase within one microsecond by a value of 1.2 A or more. This has the advantage that an occurring short-circuit current can be detected faster, for example within a microsecond, since an abnormally rapid increase in the current is detected early by the sensor and the control device.

According to a second aspect, the invention proposes an on-load tap changer for uninterrupted switching between winding taps of a tap transformer. The on-load tap-changer has a selector for power-free preselection to the selected winding tap, an on-load changeover switch for actual load changeover from the previous winding tap to the preselected winding tap, and a first A current line electrically connects the selector and the on-load changeover switch, preferably the first selector arm and the first main load branch, to one another. Furthermore, the on-load tap-changer according to the invention comprises a device for limiting short-circuit currents in the on-load tap-changer, in particular in an on-load change-over switch of the on-load tap-changer, which device is designed according to the first aspect of the invention . With regard to the device, reference is made to the preceding explanations, preferred features and/or advantages in a manner similar to that already explained for the first aspect of the invention or for one of the associated advantageous embodiments.

According to a preferred embodiment, the on-load tap-changer comprises a second current line which electrically connects the selector and the on-load changeover switch, preferably the second selector arm and the second main load branch, to one another. Furthermore, in this embodiment the device comprises a second sensor for measuring the current in the second current line. The second sensor is designed 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.

According to a third aspect, the invention proposes a method for limiting short-circuit currents in an on-load tap-changer, in particular in an on-load change-over switch of an on-load tap-changer, wherein the on-load tap-changer Apparatus constructed in accordance with the second aspect of the invention and comprising apparatus constructed in accordance with the first aspect of the invention. The method comprises the following method steps: Measuring the current in the first current line of the on-load tap-changer by means of a first sensor, transmitting a first measurement signal from the first sensor to the control device, the first measurement signal representing The measured current in the first current line of the on-load tap-changer actuates an interrupting element arranged in the first current line of the on-load tap-changer such that in The current conduction in the first current line of the on-load tap-changer is interrupted and the current is commutated to the current limiting element. The current limiting element is arranged parallel to the interruption element, in particular in a current path parallel to the first current line.

The steps of the 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 the advantageous explanations, preferred features and/or advantage.

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 current line, the current in the second The current in the two current lines, in addition to transmitting the first measurement signal, also transmits a second measurement signal from the second sensor to the control device, the second measurement signal representing the The measured current in the second current line, furthermore, the first and second measurement signals are compared with prescribed limit values by means of the control device, and when not only the first measurement signal but also the second measurement The interruption element is actuated when the signals are greater than or equal to a defined limit value. For this preferred embodiment of the method, reference is made to the explanations, preferred features and/or advantages in a manner analogous to what has already been explained for the corresponding advantageous embodiment of the device.

Further configurations and implementations of the method result directly from different configurations of the device.

The invention will be explained in more detail below by means of exemplary embodiments with reference to the drawings. Here, all described and/or illustrated features also form the subject matter of the invention per se and in any combination, independently of their composition in the individual claims or their reference. Components that are identical or functionally identical or have the same effect can be provided with the same reference symbols. The same components or components having the same function may only be explained with reference to the drawing in which they first appear. This explanation is not necessarily repeated in subsequent figures.

Description of drawings

Here, it is shown:

FIG. 1 shows an exemplary embodiment of an on-load tap-changer in a schematic diagram;

FIG. 2 shows a schematic diagram of a first embodiment of the device;

Figure 3 shows a second embodiment of the device in a schematic diagram;

FIG. 4 shows a schematic diagram of a third embodiment of the device;

FIG. 5 schematically shows a first embodiment of a method for limiting short-circuit current;

FIG. 6 shows a schematic diagram of a second embodiment of the method.

detailed description

An exemplary embodiment of an on-load tap changer 2 for a tap transformer 20 is schematically shown in FIG. 1 . The tap transformer 20 has a main winding 25 and a regulating winding 21 with different winding taps N ₁ , . . . , _{N J} , . open. For this purpose, the on-load tap-changer 2 comprises a selector 11 and an on-load changeover switch 8 , which can contact different winding taps N ₁ , . . . , of the regulating winding 21 by means of two movable selector contacts. N _J , . . . , N _N , the on-load changeover switch performs the actual load changeover from the currently switched winding tap to a new preselected winding tap. In the position of the on-load changeover switch 8 shown in FIG. 1 , the load current flows from the currently switched winding tap N _J+1 via the corresponding selector contact and the on-load changeover switch 8 to the load lead 12 .

A first embodiment of the device according to the invention is schematically shown in FIG. 2 . The device 1 serves to limit the short-circuit current in the event of a fault in the on-load tap-changer 2 , in particular the on-load change-over switch 8 . The on-load changeover switch 8 has a plurality of switching contacts and resistors for switching. However, the specific circuit arrangement of the on-load changeover switch is not critical to the practice of the invention, so this will not be discussed in more detail. The on-load tap changer 2 comprises a selector 11 with two movable selector arms, which each contact a winding tap N _J , N _J+1 of a regulating winding of a tap changer (not shown). The device 1 comprises a first sensor 3 arranged in a first current line 4 and a second sensor 9 arranged in a second current line 10 . The sensors 3 , 9 serve to continuously measure the current flowing through the respective current line 4 , 10 and to continuously transmit the measured current in the form of measurement signals M1 , M2 to the control device 6 . The sensors 3 , 9 can transmit measurement signals M1 , M2 to the control device 6 , for example via a signal connection 13 . The first current line 4 connects a first movable selector contact of the selector 11 to the on-load changeover switch 8 of the on-load tap changer 2 . Similarly, a second current line 10 connects a second movable selector contact of the selector 11 to the on-load changeover switch 8 . Arranged in the first current line 4 is an interrupting element 5 which, according to the first embodiment, is designed as an IBGT switch 5 and is designed and operated in such a way that it can be reversed in the event of a fault in the on-load changeover switch 8 . The short-circuit current that occurs. The semiconductor switching element 5 is actuated by the control device 6 when both the first measurement signal M1 and the second measurement signal M2 are greater than or equal to a predetermined limit value. The current conduction in the first current line 4 is then interrupted by the semiconductor switching element 5 , so that the current is commutated to the current limiting element 7 . The current limiting element 7 is designed here, for example, as an ohmic resistor and is arranged in parallel to the semiconductor switching element 5 or in the current path 14 in parallel to the first current line 4 and is designed such that it can limit the rising current for such a long time. Short-circuit current until a higher-level protective system, such as a power switch, is actuated and the associated tap-changer regulated by the on-load tap-changer 2 is disconnected from the transmission network.

A second embodiment of the device according to the invention is schematically shown in FIG. 3 . With respect to the device 1 in FIG. 3 , reference is made in an analogous manner to the previous explanation of the device in FIG. 2 and only the differences from the device in FIG. 2 are discussed below. The device 1 in FIG. 3 has an interruption element 5 and a current limiting element 7 , which are designed, for example, in the form of current-limiting switching cells, as they are known, for example, from DE 199 53 551 C1. The switching unit comprises a contact ring system with an electric drive, which interrupts the current conduction in the first current line 4 in the event of a short circuit. For the commutation of the current, two parallel commutation paths are provided by way of example, wherein the commutation path into which the current is commutated last has a PTC element 7 which serves as a current limiting element and is designed such that The PTC element is able to limit the short-circuit current until the higher-level protection system takes effect.

A third embodiment of the device according to the invention is schematically shown in FIG. 4 . FIG. 4 shows in particular an exemplary spatial arrangement of the device 1 according to the invention. With regard to the device 1 in FIG. 4 , reference is made in an analogous manner to the previous explanations for the devices 1 in FIGS. 3 and 4 and only the differences and supplementary features will be discussed below. In the event of a fault of the on-load tap-changer 2 , which regulates the voltage ratio of the tap-changer 20 , the device 1 limits the short-circuit current. The tap transformer 20 has a housing 23 , in particular an oil tank, with a cover 24 . The on-load tap changer 2 is arranged below the cover 24 of the transformer, wherein the selector 11 is located spatially below the on-load change-over switch 8 . The first sensor 3 , which is arranged in the first current line 4 , and the interruption element 5 , which is in the form of an explosive in the form of a detonator here by way of example, are mounted on the cover 20 outside the transformer housing 23 . The first current line 4 leads from the first selector contact contacting the winding tap N _J (not shown) via each feedthrough 22 from the inside of the housing 23 to the outside or from the outside to the inside and finally to the on-load switching Switch 8 in. The sensor 3 and the interruption element 5 are arranged between the perforations 22 . Feedthrough 22 can be, for example, a standard feedthrough configured according to DIN standards for use in the 4 kV range. Arranged in parallel to the first current line 4 is a resistor 7 which is located in the transformer housing 23 . Alternatively, one of the transition resistors in the on-load changeover switch 8 can also be used as current limiting element 7 and connected in parallel to the first current line 4 . The second sensor 9 is arranged in a section outside the on-load changeover switch 8 and the selector 11 in the second current line 10, which is connected by the second contact winding tap N _J+1 (not shown). The two selector contacts lead into the on-load changeover switch 8 . The second sensor 9 is thus located within the transformer housing 23 . However, it is also possible to arrange the sensor 9 outside the transformer housing 23 , for example on the cover 24 , and for this purpose the second current line 10 passes through the lead-through 22 from the inside of the housing 23 or from the outside. Inside boot. The load current is conveyed from the on-load changeover switch 8 via the further feedthrough 22 from the inside to the outside to the load conductor 12 .

A first specific embodiment of the method for limiting the short-circuit current is schematically shown in FIG. 5 . In this embodiment, the device 1 comprises a first sensor 3 , an interruption element 5 , a current limiting element 7 and a control device 6 . The method has, for example, successive steps 100 , 200 and 500 .

In step 100 , the current in a first current line of the on-load tap-changer is measured by means of a first sensor. In a next step 200 , a first measurement signal is transmitted from the first sensor to the control device, which first measurement signal represents the measured current in the first current line of the on-load tap-changer. In a further following step 500, the interrupting element arranged in the first current line of the on-load tap-changer is activated by the control device in such a way that the current conduction in the first current line of the on-load tap-changer is interrupted, And the current is commutated to the current limiting element.

A second embodiment of the method is shown schematically in FIG. 6 . In this embodiment, the device 1 additionally includes a second sensor 9 . The method has, for example, steps 100 , 101 , 200 , 201 , 300 , 301 and 400 , wherein steps 100 and 200 are configured identically to steps 100 and 200 in FIG. 5 . The method of FIG. 6 additionally includes a 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 also measured by means of a second sensor. In the next step 201 following step 101, in addition to the transmission of the first measurement signal in step 200, a second measurement signal is transmitted from the second sensor to the control device, which second measurement signal represents the The measured current in the second current line. In a further step 300 following step 200 , the first measurement signal is compared with a defined limit value by means of the control device. If the first measurement signal is equal to or greater than a predetermined limit value (indicated by “Yes” in FIG. 6 ), the second measurement signal is also compared with the predetermined limit value by means of the control device in step 301 . If the second measurement signal is also greater than or equal to the specified limit value (indicated by “Yes” in FIG. 6 ), in a next step 400 the interrupt element is actuated by the control device.

In the case where it was determined in step 300 that the first measurement signal is below a defined limit value (indicated by “No” in FIG. 6 ), steps 100 and 101 are carried out again. Interrupt elements are not manipulated.

In the event that in step 301 it was determined that the second measurement signal was below a defined limit value (indicated by “No” in FIG. 6 ), steps 100 and 101 are carried out again. Interrupt elements are not manipulated.

As an alternative to the sequence in which step 301 is carried out after step 300 , it is also possible first of all to compare the second measurement signal with a limit value and then to compare the first measurement signal with a limit value.

List of reference signs

1 device

2 On-load tap-changer

3 first sensor

4 First current line

5 interrupt elements

6 Controls

7 Current limiting element

8 On-load transfer switch

9 Second sensor

10 Second current line

11 selector

12 Load leads

13 Signal connections

14 Current path

20 tap transformer

21 Regulating winding

22 Feedthrough

23 The housing of 20

24 the cover of 20

25 main winding

(N ₁ ,…,N _J ,…,N _N ) winding taps

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 (13)

1. A device (1) for limiting short-circuit currents in an on-load tap-changer (2), in particular for limiting an on-load change-over switch (8) in an on-load tap-changer (2) ), the short-circuit current in which the equipment includes: - a first sensor (3) for measuring the current in the first current line (4) of the on-load tap-changer (2), - an interrupt element (5), - control means (6), and - current limiting element (7), in, - the interruption element (5) is arranged in the first current 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 designed to transmit to the control device (6) a first measurement signal M1 which represents a first current line (4) in the on-load tap-changer (2) ) in the measured current, - 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), so that the guided current changes to the current limiting element (7). 2. The device (1 ) according to the preceding claim, wherein the interrupting element (5) has a switching time for interrupting the current conduction of less than 1 millisecond. 3. The device (1) according to any one of the preceding claims, wherein the interrupting element (5) is configured as a semiconductor switching element, or the interrupting element is configured as an explosive or explosive, or the The interruption element is configured as a mechanical contact assembly with an electric drive. 4. The device (1) according to claim 1, wherein the current limiting element (7) is designed to an amperage equal to a multiple of the rated current of the on-load tap-changer (2) . 5. The device (1) according to the preceding claim, wherein the current limiting element (7) is configured as a resistor, or as an inductor, in particular as a coil . 6. The device (1) according to any one of the preceding claims, wherein the device (1) has a device for measuring the current in the second current line (10) of the on-load tap-changer (2) A second sensor (9) configured to transmit a second measurement signal M2 to the control device (6), said second measurement signal indicating that the on-load tap-changer (2) The measured current in the two current lines (10). 7. The device (1) according to the preceding claim, wherein the control device (6) is configured for, when not only the first measurement signal M1 but also the second measurement signal M2 is greater than or equal to a specified At the limit value, actuate the interrupt element (5). 8. The device (1) according to the preceding claim, wherein said prescribed limit value is a maximum value of said current which is a multiple of the rated current of the on-load tap-changer (2) times. 9. The device (1) according to claim 7, wherein said prescribed limit value is a maximum change in current within a predetermined time period. 10. An on-load tap changer (2) for uninterrupted switching between winding taps (N ₁ , ... N _J , ..., N _N ) of a tap transformer (20), The on-load tap-changer includes: - selector (11) for powerless preselection onto selected winding taps (N _J ), - on-load changeover switch (8) for actual load changeover from the winding tap (N _J-1 ) so far to the preselected winding tap (N _J ), - a first current line (4) electrically connecting the selector (11) and the on-load changeover switch (8) to each other, - Device (1) constructed according to claim 1. 11. On-load tap-changer (2) according to the preceding claim, wherein - the on-load tap-changer (2) comprises a second current line (10) electrically connecting the selector (11) and the on-load change-over switch (8) to each other, - the device (1) has a second sensor (9) for measuring the current in the second current line (10), the second sensor being designed to transmit a second measurement signal M2 to the control A device (6), the second measurement signal representing the measured current in a second current line (10) of the on-load tap-changer (2). 12. A method for limiting a short-circuit current in an on-load tap-changer (2), in particular for limiting a short-circuit current in an on-load changeover switch (8) of the on-load tap-changer (2) short-circuit current, the on-load tap-changer being an on-load tap-changer constructed according to any one of the preceding claims 10 or 11, and the on-load tap-changer comprising The device (1) constructed according to any one of the above, said method comprising the following method steps: -100: measuring the current in the first current line (4) of the on-load tap-changer (2) with the help of the first sensor (3), -200: Transmit a first measurement signal M1 from the first sensor (3) to the control device (6), said first measurement signal representing the current in the first current line (4) of the on-load tap-changer (2) the measured current, -500: actuate the interrupting element (5) arranged in the first current line (4) of the on-load tap-changer (2) such that the interruption is in the first current line (4) of the on-load tap-changer (2) The current directed and commutated to the current limiting element (7). 13. The method according to the preceding claim, wherein, - in a step (101), in addition to measuring the current in said first current line (4), a second current line in the on-load tap-changer (2) is also measured by means of a second sensor (9) The current in (10), - In step (201), in addition to the first measurement signal M1, a second measurement signal M2 is transmitted from the second sensor (9) to the control device (6), said second measurement signal representing the measured current in the second current line (10) of the switch (2), - in step (300), the first measurement signal M1 is compared with a prescribed limit value by means of the control device (6), - in step (301), the second measurement signal M2 is compared with a prescribed limit value by means of the control device (6), - In step (400), the interrupt element (5) is actuated when both the first measurement signal M1 and the second measurement signal M2 are greater than or equal to a defined limit value.

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