Measurement circuit for measuring a voltage pulse, a forming system and a method for measuring an electrical arc-over in a vacuum interrupter

Abstract

The present invention relates to a measurement circuit (10) for measuring a voltage pulse (14) in a voltage-carrying conductor of a line branch (6, 6') of a high-voltage forming system, insulated with an SF6, SF6-N2 gas mixture or a clean air gas (1), and an associated method for treating a surface of an electrical contact (2) in an electrical vacuum interrupter (3). The line branch (6, 6') is designed to conduct a high voltage from a working voltage source (4) to a vacuum interrupter (3). A partial-discharge measuring unit (8) is designed to measure the electrical voltage pulse (14) in the voltage-carrying conductor caused by an electrical arc-over (21) in the vacuum interrupter (3). For this purpose, the partial-discharge measuring unit (8) is electrically connected via an electrical impedance (11) at a low-voltage potential to a capacitive coating (9) of the line branch (6, 6'), in particular to a component of the line branch (6, 6') which is electrically coupled to the voltage-carrying conductor via its electric field.

Description

[0001] 2023PF12234 1 Description Measuring circuit for measuring a voltage pulse, a forming system and a method for measuring an electrical flashover in a vacuum interrupter The present invention relates to a measuring circuit for measuring a voltage pulse in a live conductor of a line branch of a forming system, the gas-insulated forming system, preferably insulated with SF6, SF6-N2 gas mixture and / or clean air, and a method for measuring an electrical flashover in a vacuum interrupter. In order to make interrupters, in particular vacuum interrupters, more voltage-resistant, they are conditioned with high voltage so that a surface of the contacts or tube shields is “polished”. This is done by applying high voltage to the contacts of the interrupter until a flashover occurs, in which electrons are released from the anode and impact the cathode.This impact causes the surface to become finer and finer. A key parameter for production monitoring is the arcing frequency of the interrupter tube. Robust and fast measurement technology is required to detect arcing. High voltage is typically applied to one or both ends of the interrupter tube, and current pulses are measured in the current path of the high-voltage transformers or via an antenna mounted close to the interrupter tube. However, these measurements are not very accurate and are highly susceptible to interference. On the one hand, when measuring in the current path of the high-voltage transformers, the current or current peaks are severely limited, flattened, and filtered by the high damping impedances.On the other hand, measurement via the antenna is susceptible to interference, and not only are the arcings between the contacts of the interrupter counted, but external interference is also falsely registered as arcings. 2023PF12234 2 Based on the known prior art, it is an object of the present invention to provide an improved measuring technology for pulse or arcing counting in forming systems. The present invention relates to the forming system itself insulated with SF6, SF6-N2 gas mixture and / or clean air, as well as to a measuring circuit for pulse counting in a forming system for vacuum interrupters. This also includes adapting the measuring circuit so that forming pulses measured by means of the measuring circuit can be recorded via the input of a partial discharge measuring device according to the IEC 60270 standard.The number of pulses can be fed to the process control of a forming system (e.g. PLC) via an interface of this measuring device. The software required to control the system, in which so-called forming recipes are stored, is not part of the invention. This object is achieved by a measuring circuit having the features of claim 1, which can be installed in particular in a forming system. Advantageous further developments emerge from the subclaims, the description, and the figures. Accordingly, a measuring circuit is proposed for measuring a voltage pulse in a live conductor of a line branch, which is designed to conduct a high voltage, in particular from a working voltage source to a vacuum interrupter.The measuring circuit comprises a partial discharge measuring unit, which is designed to measure the electrical voltage pulse in the live conductor caused by an electrical flashover in the vacuum interrupter. According to the invention, the partial discharge measuring unit is electrically connected to a capacitive coating of the line branch via an electrical impedance at a low-voltage potential. 2023PF12234 3 In other words, the capacitive coating can be electrically coupled to a live conductor of the line branch via its electrical field. "Electrically coupled" can mean "galvanically coupled" and / or "capacitively coupled," so that an electrical influence of a current and / or voltage change in the current-carrying conductor of the line branch is transferred to the capacitive coating.The high voltage can in particular be a high or extra-high voltage, whereas the low voltage can be a voltage below 1 ^^ ^^. Additionally or alternatively, the partial discharge measuring unit can be designed to measure a current pulse in the current-carrying conductor of the line branch. The impedance can have an electrical resistance and an electrical inductance, in particular an inductance connected in parallel with the resistance. The electrical resistance of the impedance can be 50 Ω, for example. The impedance can be designed to attenuate the voltage pulse from the capacitive coating. The impedance can be electrically connected between the partial discharge measuring unit and the capacitive coating. The capacitive coating and the impedance can form a voltage divider which reduces the high voltage, in particular by a factor of at least 1,000.This has the advantage that the influence of external disturbances on a measurement of the frequency of current flashovers is improved and signal noise is reduced. The measurement via the capacitive coating can thus be more accurate than a direct measurement in the earth path of the feeding power transformer and / or than a measurement using an antenna / probe arranged near the vacuum interrupter. The measuring circuit also includes embodiments which result in further advantages. 2023PF12234 4 One embodiment provides that the capacitive coating comprises a component of the line branch which is electrically coupled to the live conductor via its electric field, wherein the component is in particular electrically ungrounded.In other words, the component, in particular a metal component, which is coupled to the live conductor of the line branch via its electric field or is capacitively coupled to the live conductor, can be connected in series with the impedance at low voltage potential. The component can be arranged in an influence region around the live conductor of the line branch, so that in the event of a voltage pulse in the live conductor, a change in the charge state can occur in the component due to the electrical coupling via its electric field. For this purpose, the component can be ungrounded and / or electrically insulated. This offers the advantage that the voltage pulse in the live conductor can be coupled out with comparatively less signal distortion.One embodiment provides that the line branch is gas-insulated, wherein in particular the component is arranged in a gas-insulated region of the line branch. In other words, the live conductor of the line branch can be metal-encapsulated and optionally gas-insulated. The capacitive coating and / or the component can be arranged around the live conductor within the metallic encapsulation of the line branch, in which the gas-insulated region in particular can be located. For example, the line branch can be designed as a tubular conductor, in particular as a gas-insulated tubular conductor. Here, the component can be, for example, a current-carrying and ungrounded or electrically insulated and in particular metallic inner tube of the tubular conductor, which surrounds the live conductor and is additionally capacitively coupled to it.The component can be a component bent around the voltage-carrying conductor, in particular a metallic component. The inner tube can be electrically insulated from an outer tube of the tubular conductor. As a result, a voltage pulse in the current-carrying conductor of the line branch, which occurs during a flashover in the vacuum interrupter, is transmitted by the electrical coupling via its electric field to the capacitive coating, in particular the component, whereby a charge state of the capacitive coating, in particular of the component of the capacitive coating, is changed. This results in the advantage that a spatial extent of the line branch is reduced and / or the line branch can be arranged indoors. One embodiment provides that the component forms a capacitor, in particular with the current-carrying conductor.In other words, the component can form a coaxial capacitor with the live conductor, which can be capacitively coupled to the live conductor of the line branch, in particular via its electric field. The component can be non-current-carrying. The capacitor can be designed as an electrical capacitance-based high-voltage divider, which is connected in series with the impedance at low-voltage potential. This achieves a divider ratio in the range of several thousand in order to reduce the signal level to a measurable / meaningful level. One embodiment provides for the capacitor to be designed as a high-voltage capacitor, which is particularly capable of high frequencies. In other words, the high-voltage capacitor can be designed as a robust, low-loss, and high-frequency-capable capacitor.The capacitor should not have a solid-state or liquid dielectric. This offers the advantage that the capacitor is stable against sudden current or voltage changes in the high and extra-high voltage range and can couple them out without distortion. 2023PF12234 6 One embodiment provides that an attenuator and / or a frequency filter, in particular a high-pass filter or a band-pass filter, is electrically connected between the electrical impedance and the partial discharge measuring unit. In other words, the attenuator can be electrically arranged between the partial discharge measuring unit and the impedance and optionally be designed to further attenuate the voltage pulse and / or the current pulse with no or relatively low signal distortion.By connecting the impedance and the attenuator in series, the voltage pulse from the capacitive coating, in particular from the capacitor, is attenuated with relatively little signal distortion. Additionally, a frequency filter, which can be designed as a high-pass or a band-pass filter, can be electrically connected between the partial discharge measuring unit and the attenuator. The frequency filter can be designed to filter out a frequency of the alternating current from the voltage pulse. This has the advantage that the voltage pulse from the capacitor is attenuated with relatively little signal distortion to a level that prevents damage to the partial discharge measuring device. One embodiment provides that the partial discharge measuring unit is designed to determine the presence of a flashover between the contacts of the vacuum interrupter based on the measured voltage pulse.In other words, the partial discharge measuring unit can be designed as a voltage and / or current measuring device and, in particular, can be configured to perform a current and / or voltage measurement of the voltage pulse emanating from the capacitive coating relative to a reference potential. The reference potential can be at the low-voltage potential or an electrical ground. For example, the partial discharge measuring unit can be configured to determine the presence of a flashover in the vacuum interrupter when a voltage threshold value, in particular 2023PF12234 7, of the voltage pulse emanating from the capacitive coating is exceeded, and optionally to count the voltage pulses, in particular the flashovers.In addition, the partial discharge measuring unit can be designed to measure at least two voltage pulses at a time, in particular of the respective capacitive coating of at least two line branches. For example, the partial discharge measuring unit can be designed to determine the presence of a flashover in the vacuum interrupter if a voltage pulse with the same time stamp is measured at at least two inputs of the partial discharge measuring unit. In addition, the partial discharge measuring unit can be designed to perform a plausibility check of the voltage pulses measured at a time. In this case, the partial discharge measuring unit and / or a control unit data-linked to the partial discharge measuring unit can be designed to determine the presence of a flashover only if the plausibility check has been passed.In addition, the plausibility check can include a signal comparison, in particular a comparison of the amplitudes, and / or a time stamp comparison. For example, the presence of a flashover in the vacuum interrupter can be determined if the amplitudes and / or time stamps of both signals, each comprising the voltage pulse, are the same and / or a difference falls below a voltage threshold. This has the advantage that the frequency of flashovers in the vacuum interrupter can be determined more precisely and that the influence of external disturbances on a measurement of the frequency of flashovers is improved and signal noise is reduced. The measurement via the capacitive coating can therefore be more accurate than a direct measurement in the ground path of the feeding power transformer and / or a measurement using an antenna / probe arranged near the interrupter.The above-mentioned object is also achieved by a forming system, preferably insulated with an SF6, SF6-N2 gas mixture and / or a clean-air gas, with the features of claim 8. Advantageous developments of the forming system emerge from the subclaims of the measuring circuit described above as well as the present description and the figures. The said measuring circuit, in particular the line branch, can be comprised by a forming system, preferably insulated with an SF6 and / or an SF6-N2 gas mixture or a clean-air gas, for processing a surface of an electrical contact in an electrical vacuum interrupter, in particular can be arranged in or on the forming system. The forming system can be gas-insulated and / or metal-encapsulated and can be designed in particular as a high-voltage forming system.The forming system can comprise a working voltage source for providing a working voltage to a receiving device, which is designed to electrically contact at least one contact of the vacuum interrupter and additionally to adjust a distance between the contacts of the vacuum interrupter, wherein the respective contact of the vacuum interrupter is electrically connected to the working voltage source by means of the line branch between the receiving device and the working voltage source. According to the invention, a partial discharge measuring unit for measuring a voltage pulse in the live conductor of the line branch due to an electrical flashover caused by the working voltage between the contacts of the vacuum interrupter is electrically connected to a capacitive coating of the line branch via an electrical impedance at a low-voltage potential.In other words, the capacitive coating of the line branch, which is coupled to the live conductor of the system via its electrical 2023PF12234 9 field, can be connected in series with the partial discharge measuring unit via an impedance at low-voltage potential. The clean air gas can be a dry air gas or synthetic air (a mixture of pure oxygen and pure nitrogen). The forming system can also comprise the embodiments of the measuring circuit described above, and vice versa. The above-mentioned object is further achieved by a method for processing a surface of an electrical contact in an electrical vacuum interrupter, in particular by means of a forming system with the features of claim 9. Advantageous developments of the method emerge from the subclaims as well as the present description and the figures.Accordingly, a method is proposed for machining a surface of an electrical contact in a vacuum interrupter by means of an electrical flashover caused by a working voltage between the contacts of the vacuum interrupter. The working voltage is provided by a working voltage source, which is electrically connected via a line branch to a receiving device for the vacuum interrupter for electrically contacting the contacts of the vacuum interrupter. To count the flashovers in the vacuum interrupter, a measurement of a voltage pulse in a live conductor of the line branch is carried out using a partial discharge measuring unit. According to the invention, the partial discharge measuring unit is electrically connected to a capacitive coating of the line branch via an electrical impedance at a low-voltage potential.In other words, by means of the partial discharge measuring unit, a partial discharge measurement can be carried out at a measuring tap which is electrically connected to the capacitive coating of the line branch, in particular to a capacitor formed by the capacitive coating. The capacitive coating can comprise an ungrounded and in particular metallic component of the line branch, which is capacitively coupled to the live conductor of the line branch, so that the capacitor is formed. The capacitive coating can thus be or comprise an ungrounded component of the line branch which is capacitively coupled to the live conductor of the line branch and which is additionally non-live or live. The component can be designed to be exposed to an electrical influence effect of the live conductor of the line branch.For example, the component can be a non-current-carrying and electrically insulated inner tube of a metal-encapsulated and / or gas-insulated line branch, which surrounds a live conductor and is additionally electrically insulated from a grounded outer tube. A count of the current flashovers between the contacts of the interrupter can be performed based on the measurement of a partial discharge across the capacitive coating, in particular the component and / or the capacitor. A voltage pulse and / or a current pulse on an output side of the capacitive coating, in particular the capacitor, to the partial discharge measuring unit can correlate with a voltage pulse in the live conductor during a flashover between the contacts in the vacuum interrupter.This results in the advantage that, by measuring a partial discharge across the capacitive coating, a flashover between the contacts in the vacuum interrupter can be determined more precisely and without interference. This makes it possible to improve a production process in the manufacture of the vacuum interrupter, in particular a machining or polishing process for the surface of the contacts. The method also includes embodiments which result in further advantages. 2023PF12234 11 One embodiment provides that, based on the voltage pulse measured by means of the partial discharge measuring unit, the presence of a flashover between the contacts of the vacuum interrupter is determined. In other words, by measuring the partial discharge, in particular the voltage pulse, the presence of a current flashover between the contacts in the interrupter is registered.For example, a current flashover can be determined or registered if a partial discharge, in particular a voltage pulse, is measured or registered with the same time stamp at at least two inputs of the partial discharge measuring unit. This has the advantage that the number of flashovers can be determined more precisely, thereby improving the setting of an optimal operating point, in particular a working voltage and / or a distance between the contacts of the interrupter. For example, the control unit and / or the partial discharge measuring unit can count the flashovers between the contacts of the vacuum interrupter and, in addition, the working voltage can be set using the working voltage source and / or a distance between the contacts of the vacuum interrupter can be set using the recording device of the forming system based on the number of flashovers over a unit of time, in particular over one second.The partial discharge measuring unit and / or the control unit counts the number of flashovers, particularly over a time unit, in order to determine the flashover frequency. The time unit can be, for example, one second, one tenth of a second, or one hundredth of a second. For example, the partial discharge measuring unit and / or the control unit can determine the flashover frequency as the number of flashovers per second and, based on this, additionally adjust, in particular regulate, the working voltage and / or the distance between the contacts. This has the advantage of improving the adjustment, in particular the control or regulation, of the forming system to a required working voltage and / or distance between the contacts in the vacuum interrupter. For this purpose, a connected controller can read the signals via a 2023PF12234 12 interface with the partial discharge measuring device and feed them to further process control.This allows the number of arcing cycles required for surface processing to be determined more precisely, which improves the surface processing process overall. The method can have structural features of the measuring circuit and / or the forming system described above, and vice versa. To avoid repetition, reference is made to the relevant sections above regarding the method features corresponding to the measuring circuit and / or the forming system. The invention also encompasses implementations that combine the features of several of the described embodiments. Preferred further embodiments of the invention are explained in more detail in the following description of the figures.In the drawings: Figure 1 shows a schematic representation of the relationship between a voltage and / or current pulse in the line branch and the occurrence of a flashover between the contacts in the vacuum interrupter; Figure 2 shows a schematic circuit diagram of the forming system for processing the contacts of the vacuum interrupter by generating the flashovers between the contacts; and Figure 3 shows a schematic circuit diagram of the measuring circuit for measuring and counting the flashovers using a voltage or current pulse in the live conductor of the line branch. Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the different figures are provided with identical reference numerals, and a repeated description of these elements is sometimes omitted to avoid redundancy.Figure 1 shows schematically the time course of the working voltage ^^. ^ , the current ^^, and the arcing 21 between the contacts in the vacuum interrupter. The vacuum interrupter is generally used as a medium-, high-, and extra-high-voltage circuit breaker. For improved electrical isolating capability, the surface of the contacts of the vacuum interrupter is machined using arcing 21, which melts and smoothes a surface relief. The arcing 21 is an electrical discharge between the contacts in the vacuum interrupter, in particular a metal vapor arc discharge. For this purpose, the vacuum interrupter is inserted into a forming system, shown in more detail in Figure 2, which forms the arcing 21 at the contacts by applying a working voltage ^^ ^to the contacts of the vacuum interrupter. A voltage pulse 14 occurs with each arcing event 21. Analogous to the voltage pulse 14, a current pulse 15 occurs simultaneously between the working voltage source and the vacuum interrupter. The arcing events 21 become the voltage pulse 14 of the working voltage ^^ ^ and / or the current pulse 15 of a current ^^is recorded in parallel. This number ^^of flashovers 21 is an important parameter for the processing of the surface of the contacts. The flashover frequency as the number ^^of flashovers 21 per unit of time, such as per second, is an important criterion for the processing, in particular the polishing, of the surface of the contacts in the vacuum interrupter. Figure 2 shows a schematic circuit diagram of the forming system 1 for processing the contacts 2 in the vacuum interrupter 3. The forming system 1 has a working voltage source 4 for providing the working voltage ^^^ in the receiving device 5, to which it is electrically connected by means of the line branches 6, 6'. The working voltage source 4 can be designed as an interface to an electrical network and can comprise, in the respective line branch 6, 6', a transformer 18, in particular a power transformer, and a damping impedance 18 for current and voltage conversion relative to the electrical network. The working voltage ^^ ^is a high voltage, in particular an extra-high voltage. The receiving device 5 is designed to receive the vacuum interrupter 3 to be processed and to electrically contact the respective contact 2 with the working voltage source 4 via the respective line branch 6, 6', so that both contacts 2 of the vacuum interrupter 3 are electrically connected to the working voltage source 4 by means of the receiving device 5 via the respective line branch 6, 6'. In addition, the receiving device 5 is designed to adjust a distance ^^between the contacts 2. For this purpose, the receiving device 5 can comprise a corresponding actuator (not shown!). The forming system can have a control unit 16, which is designed to, based on the working voltage ^^ ^and / or the distance ^^of the contacts 2 to set a number ^^of arcing events 21 per unit of time for processing the surface of the contacts 2. To register the arcing event 21 between the contacts 2 of the vacuum interrupter 3, a partial discharge, in particular a voltage pulse 14 and / or a current pulse 15, can be measured in at least one of the line branches 6 and / or 6' by means of the partial discharge measuring unit 8. Since a high voltage, in particular an extra-high voltage, is present in the line branches 6 and 6', the partial discharge measuring unit 8 cannot be electrically connected directly to the current-carrying components of the respective line branch 6, 6' with the measuring tap 7.2023PF12234 15 For this purpose, a measuring tap 7 of the partial discharge measuring unit 8 is electrically connected to a capacitive coating 9 of the respective line branch 6, 6' via an impedance 11 at a low-voltage potential, in particular to an ungrounded component of the line branch 6, 6', which is electrically coupled to the live conductor of the line branch 6, 6' via its electric field. For example, the capacitive coating 9, in particular the component with the live conductor, can form a capacitor. For this purpose, the component is capacitively coupled to the live conductor and is ungrounded or electrically insulated. The component is also non-current-carrying.For example, the line branch 6, 6' can be designed as a tubular conductor with a live inner conductor, wherein the component can be an ungrounded inner tube surrounding the live inner conductor, which is additionally electrically insulated from a grounded outer tube. The measuring tap 7 of the partial discharge measuring unit 8 is thus electrically connected to the capacitor. The capacitor, formed in particular by the component and the live conductor, is designed as a high-voltage capacitor and additionally designed to withstand a high-voltage pulse. For example, a capacitor insulated by oil paper should not be used. A measuring circuit 10 is also arranged between the capacitor and the partial discharge measuring unit 8, in particular between the measuring tap 7 and the partial discharge measuring unit 8.The measuring circuit 10 is designed to attenuate the partial discharge from the capacitive coating 9, in particular the resulting voltage pulse 14 and / or current pulse 15, without changing a signal characteristic of the partial discharge, in particular of the voltage pulse 14 and / or current pulse 15. The measuring circuit 10 is shown in more detail in Figure 3. 2023PF12234 16 The partial discharge measuring unit 8 is designed to measure the partial discharge, in particular the voltage pulse 14 and / or current pulse 15, on the capacitive coating 9, in particular of the live conductor of the line branch 6, 6', and thus to register a flashover 21 between the contacts 2 of the vacuum interrupter 3.In addition, the partial discharge measuring unit and / or a control unit 8, which is connected to the partial discharge measuring unit 8 via a data connection, can be designed to determine the presence of a flashover 21 in the event of a partial discharge measured or registered by the partial discharge measuring unit 8, in particular the voltage pulse 14 and / or the current pulse 15. Furthermore, the partial discharge measuring unit 8 and / or the control unit 16 can be designed to count the flashovers 21 and to determine a flashover frequency as a number ^^ of flashovers 21 per unit of time. In addition, the control unit 16 can be designed to measure the working voltage ^^. ^and / or to set, in particular to regulate, the distance ^^of the contacts 2 based on the number of arcings 21 to a desired value. For this purpose, the partial discharge measuring unit 8 can be designed to transmit a signal comprising the presence of a arcing 21 and / or comprising the number ^^ of arcings 21 per unit of time to the control unit 16 via the data connection. Figure 3 shows a schematic circuit diagram of the measuring circuit 10 between the capacitive coating 9 and the partial discharge measuring unit 8. The partial discharge measuring unit 8 is electrically connected via the plugs 19 and the branch 20 to the capacitive coating 9 of the line branches 6, 6' at both contacts 2 of the vacuum interrupter 3. As a result, the partial discharge measuring unit 8 measures a voltage pulse 14 and / or a current pulse 15 on the capacitive coating 9 of the respective line branch 6, 6' at both contacts 2 of the vacuum interrupter 3.Alternatively, the partial discharge measuring unit 8 can be electrically connected via the measuring circuit 10 only to a capacitive coating 9 on a line branch 6, 6' between the 2023PF12234 17 working voltage source 4 and the recording device 5. The measuring circuit 10 comprises an impedance 11 and an attenuator 12 and optionally a frequency filter 13. The impedance 11 can comprise an electrical resistance ^^and an electrical inductance ^^. The attenuator 12, on the other hand, is designed to attenuate the voltage pulse 14 and / or the current pulse 15 and, in addition, to maintain a signal shape of the voltage pulse 14 and / or current pulse 15 or to distort it relatively little. Here, the impedance 11 is arranged electrically between the attenuator 12 and the capacitive coating 9, in particular the capacitor.Furthermore, the attenuator 12 and optionally the frequency filter 13 are electrically arranged between the impedance 11 and the partial discharge measuring unit 8. This protects the partial discharge measuring unit 8 from damage caused by the voltage pulse 14 and / or the current pulse 15, while a measurement signal is relatively little distorted by the attenuation. The partial discharge measuring unit 8 and / or the control unit 16 can be configured to measure the partial discharge, in particular the voltage pulse 14 and / or the current pulse 15, of both line branches 6, 6' and, in addition to registering a flashover 21, to compare the respective measured values ​​from both line branches 6, 6' with each other for a plausibility check. For example, a flashover 21 can be registered if a partial discharge, in particular a voltage pulse 14 and / or a current pulse 15, is measured in parallel at at least two inputs.In addition, the partial discharges, in particular voltage pulses 14 and / or current pulses 15, can have the same amplitude and / or the same time stamp at the inputs, or a difference in the amplitudes and / or the time stamp can fall below a threshold value. 2023PF12234 18 The partial discharge measuring unit 8 and / or the control unit 16 are designed to register and count the respective registered flashover 21 and to determine a flashover frequency as the number of flashovers 21 per unit of time, for example, one second. Figure 4 shows a schematic method for the partial discharge measuring unit 8 and / or the control device 16 for controlling or regulating the forming system 1. In a first step S1, a partial discharge, in particular a voltage pulse 14 and / or a current pulse 15, of the capacitive coating 9 and / or the capacitor is additionally measured against a reference potential.In a second step S2, the presence of a flashover 21 between the contacts 2 of the vacuum interrupter 3 is determined based on the measured partial discharge, in particular the measured voltage pulse 14 and / or the measured current pulse 15, in particular by means of the aforementioned measuring circuit 10. In addition, the presence of the flashover 21 is determined based on a plausibility check. The plausibility check may include an amplitude comparison and / or a timestamp comparison of the received measurement signals.For example, the presence of a flashover 21 can be determined if a partial discharge, in particular a voltage pulse 14 and / or a current pulse 15, is measured at at least two inputs of the partial discharge measuring unit 8, each with an identical time stamp and / or an identical amplitude, and / or a difference between the time stamps and / or the amplitudes between the inputs of the partial discharge measuring unit 8 falls below a threshold value. In a third step S3, a counter comprising a number ^^ of flashovers 21, in particular over a time unit, is incremented, and a flashover frequency of the flashovers 21 is determined as a number ^^ of flashovers 21 over the time unit. In a fourth step S4, a deviation of the flashover frequency from a target frequency is determined.2023PF12234 19 In a fifth step S5, based on the deviation, a control and regulation signal is sent to the working voltage source 4 and / or the receiving device 5 for setting a working voltage ^^. ^ and / or a distance ^^of the contacts 2 in the vacuum interrupter 3 to a nominal working voltage ^^ ௌ^^^ and / or a target distance ^^ ௌ^^^ calculated and output to the working voltage source 4 and / or to the receiving device 5. Where applicable, all individual features presented in the exemplary embodiments can be combined and / or exchanged with one another without departing from the scope of the invention.

[0002] 2023PF12234 20 List of reference symbols 1 Forming system 2 Contact 3 Switching tube 4 Working voltage source 5 Holding device d Distance 6 Line branch 7 Measuring tap 8 Partial discharge measuring h eit9 capacitive coating 10 measuring circuit 11 impedance 12 attenuator 13 frequency filter 14 voltage pulse 15 current pulse 16 control unit 17 transformer 18 damping resistor 19 connector 20 branching 21 flashover Z ählung Working voltage Time Distance Target working voltage Target distance S1 First step S2 Second step S3 Third step S4 Fourth step S5 Fifth step

Claims

2023PF12234 21 patent claims 1. Measuring circuit (10) for measuring a voltage pulse (14) in a live conductor of a line branch (6, 6'), which is designed to conduct a high voltage, in particular from a working voltage source (4) to a vacuum interrupter (3), comprising a partial discharge measuring unit (8) which is designed to measure the electrical voltage pulse (14) in the live conductor caused by an electrical flashover (21) in the vacuum interrupter (3), characterized in that the partial discharge measuring unit (8) is electrically connected to a capacitive coating (9) of the line branch (6, 6') via an electrical impedance (11) at a low-voltage potential. 2.Measuring circuit (10) according to claim 1, characterized in that the capacitive coating (9) comprises a component of the line branch (6, 6') which is electrically coupled to the live conductor via its electric field, wherein the component is in particular electrically ungrounded.

3. Measuring circuit (10) according to one of the preceding claims, characterized in that the line branch (6, 6') is gas-insulated, wherein in particular the component is arranged in a gas-insulated region of the line branch (6, 6').

4. Measuring circuit (10) according to one of the preceding claims, characterized in that the component forms a capacitor, in particular with the current-carrying conductor.

5. Measuring circuit (10) according to claim 4, characterized in that the capacitor is designed as a high-voltage capacitor, which is in particular high-frequency capable. 2023PF12234 22 6. Measuring circuit (10) according to one of the preceding claims, characterized in that an attenuation element (12) and / or a frequency filter (13), in particular a high-pass filter or a band-pass filter, is electrically connected between the electrical impedance (11) and the partial discharge measuring unit (8).

7. Measuring circuit (10) according to one of the preceding claims, characterized in that the partial discharge measuring unit (8) is designed to determine the presence of a flashover (21) between the contacts (2) of the vacuum interrupter (3) based on the measured voltage pulse (14).

8. Forming system (1), preferably insulated with an SF6 and / or an SF6-N2 gas mixture or a clean air gas, in particular a high-voltage forming system, for machining a surface of an electrical contact (2) in a vacuum interrupter (3) by means of a working voltage ( ^^ ^) caused electrical arcing (21) between the contacts (2) of the vacuum interrupter (3) comprising the measuring circuit (10) according to one of claims 1 to 7.

9. Method for machining a surface of an electrical contact (2) in a vacuum interrupter (3) by means of a working voltage ( ^^ ^ ) caused electrical flashover (21) between the contacts (2) of the vacuum interrupter (3), whereby the working voltage ( ^^ ^ ) is provided by a working voltage source (4) which is electrically connected via a line branch (6, 6') to a receiving device (5) for the vacuum interrupter (3) for electrically contacting the contacts (2) of the vacuum interrupter (3), wherein for counting the arcings (21) in the vacuum interrupter (3) a measurement of a voltage pulse (14) in a live conductor of the line branch (6, 6') is carried out by means of a partial discharge measuring unit (8), 2023PF12234 23 characterized in that the partial discharge measuring unit (8) is electrically connected to a capacitive coating (9) of the line branch (6, 6') via an electrical impedance (11) located at a low-voltage potential.

10. The method according to claim 9, characterized in that the capacitive coating (9) comprises a component of the line branch (6, 6') which is electrically coupled to the live conductor via its electrical field, wherein the component is in particular electrically ungrounded.

11. The method according to claim 9 or 10, characterized in that the line branch (6, 6') is gas-insulated, wherein in particular the component is arranged in a gas-insulated region of the line branch (6, 6').

12. Method according to one of claims 9 to 11, characterized in that the component forms a capacitor, in particular with the current-carrying conductor. 13.Method according to one of claims 9 to 12, characterized in that the capacitor is designed as a high-voltage capacitor, which is in particular capable of high frequencies.

14. Method according to one of claims 9 to 13, characterized in that an attenuation element (12) and / or a frequency filter (13), in particular a high-pass filter or a band-pass filter, is electrically connected between the electrical impedance (11) and the partial discharge measuring unit (8).

15. Method according to one of claims 9 to 14, characterized in that based on the voltage pulse measured by means of the partial discharge measuring unit (8). 2023PF12234 24 (14) the presence of a flashover (21) between the contacts (2) of the vacuum interrupter (3) is determined.

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