Current measuring resistor and related manufacturing method

Abstract

The invention relates to a current measuring resistor (1) for measuring current, in particular current in the kA range in a high-voltage network. The current measuring resistor (1) according to the invention comprises two connection parts (2, 3) for respectively introducing and removing current and a resistor element (4) made of a low-resistance resistance material. The resistor element (4) is arranged between the two connection parts (2, 3) in the direction of current flow and is joined to the two connection parts (2, 3) so that the current to be measured flows through the resistor element (4) during operation and generates a voltage drop across the resistor element (4). According to the invention, the connection parts (2, 3) and the resistor element (4) each have a substantially rounded cross section, in particular a substantially circular cross section, in a section perpendicular to the direction of current flow.

Description

Technical Field

[0001] The invention relates to a current measuring resistor for measuring currents, in particular currents in the kA range in high-voltage networks. The invention also relates to a corresponding production method for such a current network resistor. Background Art

[0002] Low-resistance current measuring resistors (e.g., EP 0 605 800 A1) are known from the prior art, which are capable of current measurement according to the known four-wire technique. In the process, the current to be measured flows through the low-resistance current measuring resistor, and the voltage drop across the current measuring resistor is measured. According to Ohm's law, the voltage drop across the current measuring resistor is a measure of the current flowing through the current measuring resistor. The known current measuring resistors according to EP 0 605 800 A1 are usually cut from a composite material strip and therefore have a rectangular cross-section at right angles to the direction of current flow in the profile. However, these known current measuring resistors are not suitable for current measurement of alternating currents in the kA range in high-voltage networks. The rectangular shape of the resistor leads to a highly positional and frequency-dependent distribution of amplitude and phase, especially in the case of alternating current. Summary of the invention

[0003] The invention is therefore based on the object of specifying a correspondingly improved current measuring resistor and a method for producing the same.

[0004] This object is achieved by the current measuring resistor according to the invention and the corresponding production method according to the invention.

[0005] Firstly, in accordance with the known current measuring resistor mentioned at the outset, the current measuring resistor according to the invention has two connecting parts made of a conductive material (for example copper) for respectively conducting the current to be measured into the current measuring resistor and out of the current measuring resistor.

[0006] Furthermore, according to the prior art, the current measuring resistor according to the present invention includes a resistor made of a low-resistance resistor material (e.g. CuMnNi 25-10 ) is arranged between two connecting parts in the direction of current flow and joined to the two connecting parts, so that in operation, the current to be measured flows through the resistor element and produces a voltage drop across the resistor element, thereby forming a measure of the current to be measured.

[0007] The current measuring resistor according to the invention now differs from the known current measuring resistors described at the outset in that the two connecting parts and the resistor element each have a substantially rounded cross section, in particular a substantially circular cross section, in a section plane at right angles to the current flow direction. This advantageously enables the design of a current measuring resistor for measuring high alternating currents in the kA range in high-voltage networks.

[0008] The concept of a rounded cross section used in the context of the present invention is not limited to a circular cross section that is exact in the mathematical-geometric sense. Rather, the cross section can also be reproduced by a polygon with a plurality of angles (e.g. 16 angles). However, in any case, the current measuring resistor according to the present invention differs from the known current measuring resistors with square and rectangular cross sections described at the beginning. In a preferred embodiment, the cross section of the connecting part and the resistor element is substantially circular and has only flat portions, which will facilitate the manufacturing process or enable the installation of the guide plate, as will be described in detail.

[0009] In a preferred embodiment of the invention, the outer diameter of the rounded resistor element is larger than the outer diameters of the two rounded connecting parts, and the resistor element is arranged centrally between the two connecting parts with respect to the current flow direction. Here, the current measuring resistor has a transition profile between the two outer connecting parts with the smaller outer diameter and the central resistor element with the larger outer diameter, which transition profile can be smooth and kink-free to achieve a uniform current distribution. For example, the transition profile can also have a concave section.

[0010] Furthermore, with regard to the transition profile, it should be mentioned that the transition profile is preferably only located in the connecting part, while the outer diameter of the resistor element is substantially constant along its length. However, alternatively, the transition profile may also extend into the resistor element or be arranged only in the resistor element.

[0011] It has already been mentioned above that the connecting part is joined to the resistor element, which is essentially also the case with the known current measuring resistor described at the outset.

[0012] In a variant of the invention, this connection between the resistor element and the connecting part is made by electron beam welding, as is also disclosed in the patent application EP 0 605 800 A1 already mentioned at the outset. However, when producing such an electron beam welding joint, the electron beam must extend from the outer surface to the center of the current measuring resistor. However, due to the relatively large outer diameter of the current measuring resistor according to the invention, this is relatively difficult, which is why an electron beam welding joint is not optimal.

[0013] Therefore, in another preferred variant of the invention, the connection between the resistor element and the connecting part is carried out by brazing (for example vacuum brazing), which is preferably carried out in a furnace with appropriate heating power, which is able to heat the workpieces (resistor element and connecting part) uniformly and subject them to a specific temperature distribution curve over time. Here, the cooling gradient and the cooling time also contribute to the quality of the brazed joint. Usually, brazing also requires a certain pressure to be applied to the joint. However, in the case of the current measuring resistor according to the invention, the workpieces to be connected (resistor element and connecting part) have a relatively high inherent weight, so that it is usually not necessary to apply additional external pressure to the workpieces.

[0014] Preferably, brazing is performed as part of a vacuum brazing process, although such a process is known per se in the prior art and will therefore not be described in detail.

[0015] Furthermore, it should be mentioned that the resistance material of the resistor element may contain manganese, which makes it difficult to achieve a good brazing joint. Therefore, preferably, the joining surface of the resistor element has a layer-like surface hardening before joining (brazing), which can, for example, have nickel, nickel-phosphorus (NiP), gold or silver as components. The composition of the alloy or the nickel additive is crucial for the brazing joint. The higher the quality of the nickel alloy, the faster the passivation forms, which in turn makes brazing more difficult. This surface refinement can still achieve a good brazing joint despite the use of manganese-containing resistance materials.

[0016] In the current measuring resistor according to the present invention, a printed circuit board is preferably mounted on the outer surface of the current measuring resistor in order to measure the voltage drop across the resistor element. The printed circuit board is preferably a flexible printed circuit board (flexible circuit board) which can be bent or folded in the circumferential direction according to the outer contour of the current measuring resistor.

[0017] The printed circuit board is preferably connected to the current measuring resistor by a fusion welding joint, for example by an ultrasonic fusion welding joint or a laser fusion welding joint. The fusion welding connection can, for example, be located only in the region of the connecting part in order to also electrically and mechanically connect the voltage tap inside the printed circuit board to the connecting part there. However, alternatively, the fusion welding connection between the printed circuit board and the current measuring resistor can also be located only in the region of the resistor element in order to arrange the voltage tap inside the resistor element. In addition, the fusion welding connection may also extend over the connecting part and the resistor element. Alternatively, the printed circuit board can also be connected to the current measuring resistor by a soldering connection.

[0018] With regard to the printed circuit board, it should also be mentioned that the printed circuit board is preferably at least two-layered so as to be accessible from both sides.

[0019] Furthermore, the printed circuit board can also carry a temperature sensor for measuring the temperature of the resistor element, in particular an NTC resistor (NTC: negative temperature coefficient) or a PTC resistor (PTC: positive temperature coefficient). Alternatively, a chip temperature sensor (Pt100, Pt1000, Ptx, 1-Wire, etc.) can also be used as a temperature sensor.

[0020] In a preferred embodiment of the present invention, instead of providing only a single pair of voltage taps to measure the voltage drop across the resistor element, a plurality of pairs of voltage taps are preferably provided, which are arranged at different positions on the current measuring resistor, each pair providing a corresponding voltage reading. The paired voltage taps are preferably arranged to be distributed on the circumference of the current measuring resistor, preferably equidistantly distributed. For example, the number of pairs of voltage taps may be greater than 2, 4, 8, 12 or 14, and in a preferred embodiment of the present invention, exactly 16 pairs of voltage taps are provided.

[0021] For example, the voltage tap can be attached directly to the printed circuit board and rest directly on the lateral surface of the connection part. The voltage tap can then be attached to the side of the printed circuit board facing the current measuring resistor and brought into contact with the connection part after welding the printed circuit board. Preferably, however, the voltage tap is accessible by plating on both sides of the printed circuit board.

[0022] It has already been briefly mentioned above that each pair of voltage taps provides a voltage measurement value. For example, an average value can then be derived from the individual voltage measurements, which then forms a measure for the current flowing through the current measuring resistor. However, preferably, weighting resistors are provided to weight the individual voltage measurements, so that the resulting measurement value is determined from the weighted voltage measurements. These weighting resistors can also be arranged on a printed circuit board.

[0023] The paired voltage taps are preferably connected to a measuring circuit for determining the voltage drop across the resistor element, which preferably calculates the voltage drop across the resistor element from the weighted voltage measurements. The measuring circuit is preferably not arranged on the printed circuit board itself, but on at least one separate measuring card which is connected to the printed circuit board via lines.

[0024] The measuring circuit can also be connected to a data interface in order to transmit the measured value of the voltage drop to an external analysis and evaluation unit. Preferably, the data interface is an electro-optical data interface, which transmits the measured value to the external analysis and evaluation unit via an optical fiber.

[0025] In order to create redundancy in the measurement, preferably at least two measuring boards are provided, each having a measuring circuit, the two measuring circuits being connected to the printed circuit board on the input side and receiving the voltage measurement values ​​of the respective pair of voltage taps.

[0026] Each measurement circuit can have at least two or at least three measurement paths, each measurement path receives the measured value of the voltage drop on the resistor element from the printed circuit board. In the case of three measurement paths, for example, the first two measurement paths can have the same signal amplification, while the third measurement path can have a lower signal amplification.

[0027] It has already been briefly mentioned above that the outer contour of the current measuring resistor does not have to be exactly rounded, but can have flattened sections on the lateral surfaces in order to mount the printed circuit board on the flattened sections in a plane-parallel manner.

[0028] In a preferred embodiment of the invention, a plurality of flat portions distributed on the circumference of the current measuring resistor are arranged in the lateral surface of the current measuring resistor, and preferably more than 2, 4, 6, 8, 10, 12 or 14 flat portions. In a preferred embodiment, the current measuring resistor is a polygon with 16 flat portions in cross section. Here, the printed circuit board is bent multiple times according to the number of flat portions in the current measuring resistor, and contains flat printed circuit board sections between the bends, each flat printed circuit board section being mounted on a corresponding one of the flat portions in a plane-parallel manner. In an embodiment of the current measuring resistor according to the invention, there are 16 flat portions on the lateral surface of the current measuring resistor, and the printed circuit board has corresponding 16 flat printed circuit board sections, which are then respectively located on one of the flat portions in a plane-parallel manner.

[0029] It should be mentioned here that the flat portion preferably extends in the axial direction from the region of the resistor element into the region of the adjacent connecting component.

[0030] The above-mentioned measuring circuit and other electronic components of the current measuring resistor require a power supply during operation, which in principle can be provided in a conventional manner in the case of the current measuring resistor according to the present invention. However, in a preferred embodiment of the present invention, the current measuring resistor has at least one coil for collecting energy from the magnetic field of the current measuring resistor by energy collection. In operation, the current flowing through the current measuring resistor generates a magnetic field passing through the energy collection coil, thereby achieving energy collection. The coil can then provide the electrical energy required to operate the sensing circuit alone or by an additional energy supply. Preferably, the coil has at least 20, 50, 100 or 140 windings, and exactly 150 windings are provided in a preferred embodiment of the present invention. In addition, the coil preferably includes a magnetic core that surrounds the connecting part in an annular shape and is wound by the coil. In a preferred embodiment of the present invention, a plurality of coils are provided, each coil respectively and correspondingly annularly surrounding one of the two connecting parts.

[0031] Furthermore, the current storage device can also be integrated in the current measuring resistor, in particular at least one so-called power cap, whose capacitance is at least 10 mF, 50 mF, 100 mF, 500 mF or at least 1000 mF.

[0032] Photovoltaic cells can also be integrated in the current measuring resistor for separate or auxiliary power supply.

[0033] The conductor material is preferably copper or a copper alloy, but other conductor materials are possible within the scope of the invention. However, the conductor material of the connecting part should have a lower resistivity than the resistor material of the resistor element.

[0034] For example, the resistive material of the resistor element may be a copper-manganese-nickel alloy, in particular with 25% by weight manganese, 10% by weight nickel and the balance copper or with 12% by weight manganese, 2% by weight nickel and the balance copper.

[0035] The resistive material of the resistor element preferably has a resistivity of less than 1,000 μΩcm, 500 μΩcm, 250 μΩcm, 100 μΩcm or 50 μΩcm.

[0036] On the other hand, the conductor material of the connection part preferably has a resistivity of less than 20 μΩcm, 10 μΩcm, 5 μΩcm or 2 μΩcm.

[0037] Furthermore, it should be mentioned that the resistor element, the first connection part and / or the second connection part are preferably solid structures without cavities. On the one hand, this is advantageous, since cavities in the current measuring resistor could allow water to penetrate. On the other hand, a solid design of the current measuring resistor is also advantageous, since the current measuring resistor according to the invention must have a large mass in order to have a sufficient short-circuit resistance so that the thermal power losses generated in the event of a short circuit can be buffered without significantly changing the resistance value.

[0038] It should also be mentioned that the connecting parts can each have an axially extending longitudinal groove in their lateral surfaces, said longitudinal groove starting from the end face of the connecting part. These longitudinal grooves advantageously achieve an anti-rotation protection.

[0039] Furthermore, the two connecting parts can each have an axially extending blind hole in their end faces, in particular with an internal thread, the blind hole being preferably arranged centrally and coaxially. For example, the blind hole can be connected to a cable.

[0040] Additionally, the connecting parts can each have at least one radially extending blind hole in their lateral surfaces for housing assembly, wherein the blind hole can be located, for example, in a transition contour of a current measuring resistor.

[0041] It has already been mentioned above that the current measuring resistor is formed with a polygonal cross section in the region of the resistor element in order to be able to mount a PCB that has been folded several times. Therefore, preferably, corresponding annular grooves are provided in the connecting part, which have a polygonal cross section with the same orientation in the circumferential direction. These annular grooves with a polygonal cross section then serve as a trimming aid in the automated assembly of printed circuit boards.

[0042] The current measuring resistor according to the invention also differs from the known current measuring resistors described at the outset in that it has larger dimensions, which are suitable for current measurement in the kA range. Thus, the outer diameter of the rolled resistor element may be at least 6 cm, 7 cm, 8 cm or 9 cm, and in a preferred embodiment of the invention the outer diameter of the rolled resistor element is substantially 10 cm. On the other hand, the outer diameter of the rolled connecting part is preferably at least 2 cm, 3 cm, 4 cm or 5 cm and is therefore significantly smaller than the outer diameter of the rolled resistor element.

[0043] On the other hand, in the axial direction the current measuring resistor according to the invention preferably has a relatively large length of at least 10 cm, 20 cm, 30 cm, 40 cm, 50 cm or 60 cm, wherein in a preferred embodiment the length of the current measuring resistor is substantially 64 cm.

[0044] On the other hand, a single resistor element preferably has an axial length in the current flow direction of at least 1 cm, 2 cm, 3 cm, 4 cm, 5 cm or 6 cm, wherein in a preferred embodiment the length of the resistor element is substantially 7 cm.

[0045] Therefore, the axial length of each connecting member in the current flow direction is preferably at least 10 cm, 20 cm, 25 cm or 30 cm. In a preferred embodiment of the present invention, the axial length of each connecting member is substantially 31 cm.

[0046] In order to allow sufficient current carrying capacity and short-circuit strength, in the current measuring resistor according to the invention, the mass of the connecting parts and the resistor elements is preferably also significantly greater than in the known current measuring resistors described at the beginning. Therefore, each connecting part preferably has a mass of at least 1 kg, 2 kg, 5 kg, 10 kg, 15 kg or 20 kg, and in a preferred embodiment substantially 22 kg. On the other hand, the resistor elements preferably have a mass of at least 0.5 kg, 1 kg, 1.5 kg or 2 kg, and in a preferred embodiment substantially 2 kg.

[0047] The current measuring resistor according to the invention also differs from known current measuring resistors in that it has a very high continuous current carrying capacity of at least 1 kA, 5 kA, 10 kA, 15 kA, 50 kA, 75 kA, 95 kA or even at least 100 kA for alternating current.

[0048] Furthermore, the current measuring resistor is also designed for relatively high voltage levels and is suitable for voltages of at least 1 kV, 5 kV, 10 kV, 50 kV, 110 kV, 220 kV or at least 380 kV for alternating current.

[0049] Furthermore, it should be mentioned that the present invention not only requires the protection of the current measuring resistor according to the present invention as an individual component. Rather, the present invention also requires the protection of the corresponding manufacturing process. The individual process steps of the manufacturing process according to the present invention have already been derived from the above description, so that a separate description of the manufacturing process according to the present invention can be omitted. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Other advantageous further embodiments of the present invention are indicated in the technical solution of the present invention or explained in more detail below with reference to the accompanying drawings in conjunction with the description of the preferred embodiments of the present invention. The accompanying drawings show:

[0051] Figure 1 is a side view of a current measuring resistor according to the present invention,

[0052] Figure 2 yes Figure 1 Another side view of the current measuring resistor according to the present invention,

[0053] Figure 3 is based on Figure 2 The cross-sectional view of section AA in

[0054] FIG. 4 is a detailed view of the detail area Z in FIG. 3 ,

[0055] FIG. 5 is a detailed view of the detail area X in FIG. 3 ,

[0056] Figure 6 is an exploded perspective view of a current measuring resistor according to the present invention,

[0057] Figure 7 The manufacturing process according to the present invention is shown in the form of a flow chart. DETAILED DESCRIPTION

[0058] The figures show an embodiment of a current measuring resistor 1 according to the invention which can be used for current measurement in the kA range in a high voltage network, for example 220 kV AC.

[0059] The current measuring resistor 1 originally has two connecting parts 2, 3 made of copper, which are used to connect the current I to be measured. AC Introduced into the current measuring resistor 1 and led out from the current measuring resistor 1 .

[0060] In the direction of current flow between the two connecting parts 2, 3, there is a connection made of a resistive material (e.g. CuMnNi 25-10 ) made of resistor element 4.

[0061] The resistor element 4 is joined at its two end faces to the two connection parts 2, 3 by a brazing joint. In order to achieve this brazing process, the resistor element 4 has a layer-like surface treatment 5, 6 of nickel phosphorus (NiP) on both joining surfaces, despite the interference of the manganese content in the resistor material. However, the surface treatment 5, 6 is applied before the brazing connection to enable or promote the subsequent brazing process, regardless of the manganese content in the resistor element 4.

[0062] The connecting parts 2, 3 and the resistor element 4 have essentially a substantially circular cross section with a smaller outer diameter d1 in the region of the connecting parts 2, 3 and a larger outer diameter d2 in the region of the resistor element 4. For the diameter matching between the two outer diameters d1, d2, the connecting part 2 has a transition profile 7 and the other connecting part 3 has a corresponding transition profile 8. The two transition profiles 7, 8 form the transition from the small outer diameter d1 of the connecting parts 2, 3 to the larger outer diameter d2 of the resistor element 4. It should be mentioned here that the two transition profiles 7, 8 each have a concave section to ensure that the current density is as uniform as possible even in the transition profiles 7, 8.

[0063] On the end faces of the two connecting parts 2 , 3 there are respectively coaxial, central blind holes 9 , 10 with an internal thread, which in each case allow a cable to be connected.

[0064] Furthermore, both connection parts 2 , 3 have longitudinal grooves 11 , 12 in their lateral surfaces, which enable anti-rotation.

[0065] Furthermore, in the transition profiles 7 , 8 of the two connecting parts 2 , 3 there are several radially extending blind holes 13 , 14 , 15 and 16 , which enable the housing assembly, as will be described in detail below.

[0066] The cross section of the resistor element 4 and the adjacent areas of the two connecting parts 2, 3 is not exactly circular. Instead, the current measuring resistor 1 has a total of sixteen flat portions 17 in the center, which are equidistantly distributed on the circumference. The resistor element 4 therefore has a polygonal cross section with sixteen corners in a section at right angles to the current flow direction. The flat portions 17 are used to mount a flexible printed circuit board 18, which is bent several times according to the number of flat portions 17. Between the individual bends of the printed circuit board 18, there are flat printed circuit board sections, each of which rests on a corresponding one of the flat portions 17 in a plane-parallel manner.

[0067] On its inner side facing the connection elements 2 , 3 , the printed circuit board 18 has sixteen pairs of voltage taps 19 , 20 , which are plated through and rest against the connection elements 2 , 3 and thus measure the voltage drop across the resistor elements in pairs in each case.

[0068] A printed circuit board 18 with voltage taps 19 , 20 is connected to the connection parts 2 , 3 by means of an ultrasonic welding connection.

[0069] In the two connecting parts 2, 3, there are two annular grooves 21, 22, which also have a polygonal cross section with sixteen corners. This polygonal cross section of the annular grooves 21, 22 enables precise angular alignment during automated manufacturing and serves as a manufacturing aid during assembly of the printed circuit board 18.

[0070] As already mentioned above, the current measuring resistor 1 is used for high current measurement in high-voltage networks. In order to obtain sufficient current carrying capacity and a correspondingly high short-circuit strength, the current measuring resistor 1 has large dimensions and a relatively large mass. Therefore, the total axial length of the current measuring resistor 1 is 640 mm. The mass of the connecting parts 2, 3 is approximately 18-22 kg respectively, while the mass of the resistor element 4 is approximately 2.5 kg. The outer diameter d2 is approximately 10 cm, while the outer diameter d1 of the connecting parts 2, 3 is correspondingly smaller.

[0071] Figure 6 The exploded view in FIG. 1 further shows that the connection parts 2 , 3 are respectively surrounded by energy harvesting coils 23 , 24 , which harvest electrical energy from the magnetic field of the current measuring resistor 1 to operate the measuring circuit.

[0072] The measuring circuits are redundantly arranged on two measuring cards 25 , 26 , which are connected to the lead board 18 via lines.

[0073] Furthermore, it should be mentioned that the printed circuit board 18 carries weighting resistors in addition to the voltage taps 19, 20 in order to weight the voltage measurement values ​​of each pair of voltage taps 19, 20. The weighted voltage measurement values ​​are then transmitted from the printed circuit board 18 via lines to the two measuring cards 25, 26, where they are processed.

[0074] The measuring cards 25, 26 also have an electro-optical data interface for transmitting the measuring data to an external analysis and evaluation unit via optical fiber.

[0075] Furthermore, it can be seen from the exploded view that the current measuring resistor 1 has two housing parts 27 , 28 which can be attached to the blind holes 13 - 16 in the current measuring resistor 1 .

[0076] The housing part 28 here forms a slide-in compartment 29 for the two measuring cards 25 , 26 , wherein the slide-in compartment 29 can be closed by a cover 30 .

[0077] In the following, reference is made to Figure 7 The flowchart describes the manufacturing process according to the present invention.

[0078] In a first step S1, two connecting parts 2, 3 made of copper and The resistor element 4 is produced as a rounded blank.

[0079] In a further step S2 , the blank is then turned and / or milled.

[0080] In the following step S3 , the surface of the resistor element is then subjected to surface modification on the bonding surface in order to provide the surface modified portions 5 , 6 .

[0081] After this surface tempering, the brazing process can then be started in step S4 in order to join the resistor element 4 to the connection parts 2 , 3 .

[0082] In the next step S5 , the current measuring resistor 1 is then stabilized and cleaned.

[0083] Then, in step S6 , the current measuring resistor 1 is turned to obtain a desired outer contour with outer diameters d1 , d2 .

[0084] In a further step S7 , a flat portion 17 is then milled onto the rounded outer surface of the current measuring resistor 1 .

[0085] Then, in step S8 , the printed circuit board 18 is attached to the outer surface of the current measuring resistor 1 by ultrasonic welding.

[0086] In step S9 , the housing consisting of the two housing parts 27 , 28 is then mounted.

[0087] Then, in step S10 , the two measuring cards 25 , 26 are inserted into the slide-in compartment 29 .

[0088] Then, in step S11 , the energy collection coils 23 , 24 are assembled.

[0089] Finally, in step S12 , the housing cover is then assembled.

[0090] The invention is not limited to the preferred embodiments described above. On the contrary, a large number of variants and variations are possible, which also exploit the idea of ​​the invention and therefore fall within the scope of protection. In particular, the invention also claims the subject matter and features of the dependent claims, independently of the individual claims cited and without the features of the main claim. The invention therefore comprises various aspects that enjoy protection independently of each other. For example, many aspects of the invention can also be used for current measuring resistors that do not have a rounded cross section.

[0091] Reference numerals list

[0092] 1 Current measurement resistor

[0093] 2, 3 Connection parts, used to introduce or remove the current to be measured

[0094] 4 Resistor elements

[0095] 5, 6 Surface treatment portion on the bonding surface of the resistor element

[0096] 7, 8 Transition profile between connecting parts and resistor elements

[0097] 9, 10 Axial blind hole in the end face of the connection component

[0098] 11, 12 Longitudinal grooves in connecting parts

[0099] 13-16 Blind holes for housing assembly

[0100] 17 Flat part

[0101] 18 Flexible Printed Circuit Board

[0102] 19, 20 voltage taps

[0103] 21, 22 Annular groove in connecting part

[0104] 23, 24 Energy harvesting coils for energy recovery through energy harvesting

[0105] 25, 26 measurement card

[0106] 27, 28 Shell part

[0107] 29 Slide-in compartments

[0108] 30 Slide-in compartment cover

[0109] d1 External diameter of the area of ​​the connecting parts

[0110] d2 outer diameter of the resistor element area

Claims

1. A method for measuring current (I AC ) of a current measuring resistor (1) having a) a first connecting member (2) made of a conductive material, used to transfer the current (I AC ) introduces a current measuring resistor (1), b) a second connecting member (3) made of a conductive material, for transferring the current (I AC ) is derived from the current measuring resistor (1), and c) a resistor element (4) made of a low-resistance resistive material, the resistor element (4) being arranged between the first connecting member (2) and the second connecting member (3) in the current flow direction and being joined to the two connecting members (2, 3) so as to make the current (I AC ) flows through the resistor element (4) during operation and generates a voltage drop (U MESS ), d) A printed circuit board (18) is attached to the outer surface of the current measuring resistor (1) in order to measure the voltage drop (U MESS ), e) the first connecting member (2), the second connecting member (3) and the resistor element (4) are connected to the current (I AC ) have rounded cross sections in the cross sections at right angles to the flow direction, It is characterized in that f) the printed circuit board (18) is a flexible printed circuit board (18) that is bent or folded in the circumferential direction according to the outer contour of the current measuring resistor (1), The printed circuit board (18) is arranged in the axial direction in the region of the resistor element (4) and extends on both sides in the axial direction to the outer surfaces of the two connecting parts (2, 3).

2. The current measuring resistor (1) according to claim 1, characterized in that a) the outer diameter (d2) of the rounded resistor element (4) is larger than the outer diameter (d1) of the two rounded connecting parts (2, 3), and / or b) the resistor element (4) is arranged centrally between the two connection parts (2, 3) with respect to the direction of current flow, and / or c) the current measuring resistor (1) has a transition contour (7, 8) between two outer connecting parts (2, 3) with a smaller outer diameter (d1) and a central resistor element (4) with a larger outer diameter (d2), d) To obtain a uniform current distribution, the transition profiles (7, 8) are smooth and kink-free, e) the transition profiles (7, 8) are located only in the connecting parts (2, 3), and / or f) The transition profile (7, 8) is at least partially concave.

3. The current measuring resistor (1) according to any one of the preceding claims, characterized in that The resistor element (4) is joined to the first connection part (2) and the second connection part (3) by one of the following connection types: a) Brazing connection, b) Fusion welding connection.

4. The current measuring resistor (1) according to claim 1 or 2, characterized in that The resistor element (4) has a layered surface-treated portion (5, 6) at the joint with the two connecting components (2, 3).

5. The current measuring resistor (1) according to claim 1 or 2, It is characterized in that a) The printed circuit board (18) is connected to the current measuring resistor (1) via a solder joint or a weld joint, and / or b) the welded joint of the printed circuit board (18) is located in the region of the connecting components (2, 3) and / or in the region of the resistor element (4), and / or c) the printed circuit board (18) has at least two printed circuit board layers, and / or d) The printed circuit board (18) also carries a temperature sensor for measuring the temperature of the resistor material.

6. The current measuring resistor (1) according to claim 5, characterized in that a) providing a plurality of pairs of voltage taps (19, 20), each pair of voltage taps (19, 20) measuring a voltage drop (U MESS ) and provide the corresponding voltage reading, and / or b) pairs of voltage taps (19, 20) are arranged distributed on the circumference of the current measuring resistor (1) so as to measure the voltage drop (U) across the resistor element (4) at a plurality of different points distributed on the circumference of the current measuring resistor (1) MESS ), c) the number of pairs of voltage taps (19, 20) is greater than 2, 4, 8, 12, 14, and / or d) the voltage tap is attached directly to the printed circuit board (18) and rests directly on the outer surface of the connection part (2, 3), and / or e) the paired voltage taps (19, 20) are respectively connected to weighted resistors so as to weight the individual voltage measurements according to the resistance values ​​of the weighted resistors, and / or f) The weighted resistors are arranged on a printed circuit board (18).

7. The current measuring resistor (1) according to claim 6, It is characterized in that a) The pair of voltage taps (19, 20) is connected to a measuring circuit which determines the voltage drop (U) across the resistor element (4) from the measured value MESS ), and / or b) The measuring circuit calculates the voltage drop (U) across the resistor element (4) from the weighted voltage measurements. MESS ), and / or c) the measuring circuit is not arranged on the printed circuit board (18), but on at least one separate measuring card (25, 26), said measuring card (25, 26) being connected to the printed circuit board (18) via lines, and / or d) The measuring circuit is connected to the data interface to measure the voltage drop (U MESS ) is transmitted to an external analysis and evaluation unit, e) the data interface is an electro-optical data interface for transmitting the measured values ​​to an external evaluation unit via an optical waveguide, and / or f) in order to create redundancy in the measurement, two measuring cards (25, 26) are provided, each measuring card (25, 26) having a measuring circuit, and / or g) the measuring circuit has at least two or at least three measuring paths, wherein each measuring path receives a measured value of the voltage drop across the resistor element (4) from the printed circuit board (18), and / or h) The first measurement path and the second measurement path have the same signal amplification, while the third measurement path has a lower signal amplification.

8. The current measuring resistor (1) according to claim 5, It is characterized in that a) the rounded outer contour of the current measuring resistor (1) has at least one flat flat portion (17) on the lateral surface of the current measuring resistor (1) so that a printed circuit board (18) can be mounted on the flat portion (17) in a plane-parallel manner, and / or b) on the lateral surface of the current measuring resistor (1), a plurality of flat portions (17) are distributed on the circumference of the current measuring resistor (1), and / or c) the flat portion (17) is located in the outer surface of the resistor element (4), and / or d) the flat portion (17) extends into the connecting parts (2, 3) on both sides in the direction of current flow, and / or e) The printed circuit board (18) is bent a number of times according to the number of the flat portions (17) and has a plurality of flat printed circuit board sections, each of which is mounted on a corresponding one of the flat portions (17) in a plane-parallel manner.

9. The current measuring resistor (1) according to any one of claims 1-2 and 6-8, It is characterized in that a) providing at least one coil (23, 24) for collecting energy from the magnetic field of the current measuring resistor (1) by energy harvesting, and / or b) the coils (23, 24) provide the electrical energy required to operate the measuring circuit, and / or c) the coil (23, 24) has at least 20, 50, 100, 140 windings, and / or d) the coil (23, 24) comprises a magnetic core, and / or e) for energy collection, a plurality of coils (23, 24) are provided, each coil being annularly surrounding a respective one of the two connection parts (2, 3), and / or f) integrating a current storage device into the current measuring resistor (1), and / or g) Integrate a photovoltaic cell into the current measuring resistor (1) for sole or auxiliary power supply.

10. The current measuring resistor (1) according to any one of claims 1-2 and 6-8, It is characterized in that a) The conductor material is copper or copper alloy, and / or b) the conductor material of the connection parts (2, 3) has a lower resistivity than the resistor material of the resistor element (4), and / or c) the resistance material of the resistor element (4) is a copper-manganese-nickel alloy, and / or d) the resistor material of the resistor element (4) has a resistivity of less than 1000 μΩcm, 500 μΩcm, 250 μΩcm, 100 μΩcm or 50 μΩcm, and / or e) the conductor material has a resistivity of less than 20 μΩcm, 10 μΩcm, 5 μΩcm or 2 μΩcm, and / or f) the resistor element (4), the first connecting part and / or the second connecting part are solid structures without cavities, and / or g) the connecting parts (2, 3) have axially extending longitudinal grooves (11, 12) on their lateral surfaces, respectively, the longitudinal grooves starting from the end faces of the connecting parts (2, 3), and / or h) the two connecting parts (2, 3) have at least one radially extending blind hole (13-16) on their lateral surfaces, respectively, for housing assembly, and / or i) The two connecting parts (2, 3) have axially extending blind holes (9, 10) on their end faces, and / or j) the two connecting parts (2, 3) have on their lateral surfaces respectively a circumferential annular groove (21, 22), said circumferential annular groove (21, 22) having a polygonal cross section as a manufacturing aid, and / or k) the outer diameter (d2) of the rounded resistor element (4) is at least 6 cm, 7 cm, 8 cm or 9 cm, and / or l) the outer diameter (d1) of the rounded connecting parts (2, 3) is at least 2 cm, 3 cm, 4 cm or 5 cm, and / or m) the current measuring resistor (1) has an axial length in the direction of current flow of at least 10 cm, 20 cm, 30 cm, 40 cm, 50 cm or 60 cm, and / or n) the resistor element (4) has an axial length in the direction of current flow of at least 1 cm, 2 cm, 3 cm, 4 cm, 5 cm or 6 cm, and / or o) the two connecting parts (2, 3) each have an axial length of at least 10 cm, 20 cm, 25 cm or 30 cm in the direction of current flow, and / or p) the two connecting parts (2, 3) each have a mass of at least 1 kg, 2 kg, 5 kg, 10 kg, 15 kg or 20 kg, and / or q) the resistor element (4) has a mass of at least 0.5 kg, 1 kg, 1.5 kg or 2 kg, and / or r) the current measuring resistor (1) has a continuous current carrying capacity of at least 1 kA, 5 kA, 10 kA, 25 kA, 50 kA, 75 kA, 95 kA or at least 100 kA for alternating current, and / or s) the current measuring resistor (1) is suitable for a voltage level of at least 1 kV, 5 kV, 10 kV, 50 kV, 110 kV, 220 kV or at least 380 kV for alternating current, and / or t) the first connection member, the second connection member and / or the resistor element (4) are connected to the current (I AC ) have a polygonal cross-section with at least 12, 14 or 16 corners in a cross-section at right angles to the flow direction of the liquid to form a rounded cross-section.

11. The current measuring resistor (1) according to claim 1, It is characterized in that The current (I AC ) is the current in the kA range in the high voltage network (I AC ), the first connecting member (2), the second connecting member (3) and the resistor element (4) are connected to the current (I AC ) have a circular cross-section in a cross-section at right angles to the flow direction.

12. The current measuring resistor (1) according to claim 3, It is characterized in that The soldered connection comprises a brazed connection and the welded connection comprises an electron beam welded connection.

13. The current measuring resistor (1) according to claim 3, It is characterized in that The soldered connection comprises a vacuum brazed connection.

14. The current measuring resistor (1) according to claim 4, characterized in that The surface modified parts (5, 6) contain nickel, nickel-phosphorus, gold or silver as components.

15. The current measuring resistor (1) according to claim 5, It is characterized in that b) The printed circuit board (18) is connected to the current measuring resistor (1) by: d1) Ultrasonic welding, or d2) Laser welding connection, and / or e) The printed circuit board (18) also carries an NTC resistor or a PTC resistor for measuring the temperature of the resistive material.

16. The current measuring resistor (1) according to claim 6, characterized in that c) There are exactly 16 pairs of voltage taps (19, 20).

17. The current measuring resistor (1) according to claim 8, It is characterized in that b) The plurality of flat portions (17) comprises at least 2, 4, 6, 8, 10, 12 or 14 flat portions.

18. The current measuring resistor (1) according to claim 8, It is characterized in that b) The plurality of flat portions (17) are exactly 16 flat portions.

19. The current measuring resistor (1) according to claim 9, It is characterized in that b) the coils (23, 24) alone or together with an additional power supply provide the power required to operate the measuring circuit, and / or c) the coils (23, 24) have exactly 150 windings, and / or f) the current storage device is at least one power cap having a capacitance of at least 10 mF, 50 mF, 100 mF, 500 mF or at least 1,000 mF.

20. The current measuring resistor (1) according to claim 10, It is characterized in that c) the resistance material of the resistor element (4) is a copper-manganese-nickel alloy, c1) containing 25% by weight of manganese, 10% by weight of nickel and the balance copper, or c2) containing 12% by weight of manganese, 2% by weight of nickel and the balance copper, and / or h) the two connecting parts (2, 3) each have at least one radially extending blind hole (13-16) in the transition profile (7, 8) for housing assembly, and / or i) the blind holes (9, 10) are blind holes with internal threads, and / or k) the outer diameter (d2) of the rounded resistor element (4) is 10 cm, and / or m) the current measuring resistor (1) has an axial length of 64 cm in the direction of current flow, and / or n) the resistor element (4) has an axial length of 7 cm in the direction of current flow, and / or o) the two connecting parts (2, 3) each have an axial length of 31 cm in the direction of current flow, and / or p) the two connecting parts (2, 3) each have a mass of 22 kg, and / or q) The resistor element (4) has a mass of 2.5 kg.

21. The current measuring resistor (1) according to claim 10, It is characterized in that i) The blind holes (9, 10) are centrally and coaxially positioned blind holes.

22. A method for manufacturing a current measuring resistor (1) according to any one of the preceding claims, comprising the following steps: a) providing a first connecting member (2) made of a conductive material for transferring the current (I AC ) is introduced into the current measuring resistor (1), b) providing a second connecting member (3) made of a conductive material for transferring the current (I AC ) is derived from the current measuring resistor (1), c) providing a resistor element (4) made of a resistor material having a low resistance, d) joining a resistor element (4) to two connection parts (2, 3) to form a current measuring resistor (1), so that the resistor element (4) is arranged between the first connection part (2) and the second connection part (3) in the current flow direction, and the current to be measured (I AC ) flows through the resistor element (4) during operation and generates a voltage drop (U MESS ), e) A printed circuit board (18) is attached to the outer surface of the current measuring resistor (1) in order to measure the voltage drop (U MESS ), f) the first connection member (2), the second connection member (3) and the resistor element (4) each have a rounded cross section in a section perpendicular to the current flow direction, It is characterized in that g) the printed circuit board (18) is a flexible printed circuit board (18) that is bent or folded in the circumferential direction according to the outer contour of the current measuring resistor (1), wherein the printed circuit board (18) is arranged in the axial direction in the region of the resistor element (4), And it extends to the outer surfaces of the two connecting parts (2, 3) on both sides in the axial direction.

23. The manufacturing method according to claim 22, characterized in that: The resistor element (4) is joined to the two connection parts (2, 3) by one of the following joining methods: a) Brazing, b) Fusion welding.

24. The manufacturing method according to claim 23, characterized in that: Before joining the resistor element (4) to the two connection parts (2, 3), the following steps are performed: Surface conditioning of the joining surfaces.

25. The manufacturing method according to any one of claims 22 to 24, characterized in that: After joining the resistor element (4) to the two connection parts (2, 3), the following steps are performed: a) shaping the outer contour of the current measuring resistor (1), and / or b) forming at least one flat portion (17) on a lateral surface of the current measuring resistor (1) to mount a printed circuit board (18) on the flat portion (17) in a plane-parallel manner.

26. The manufacturing method according to any one of claims 22 to 24, characterized in that: The manufacturing method comprises the following steps: a) mounting a printed circuit board (18) for measuring the voltage drop across the resistor element (4) on the outer surface of the resistor element (4), and / or b) mounting a housing (27, 28) on the current measuring resistor (1), said housing surrounding the resistor element (4), and / or c) inserting at least one measuring card (25, 26) into the housing (27, 28), said measuring card (25, 26) measuring the voltage drop (U MESS ), and / or d) installing at least one coil (23, 24) for collecting energy from the magnetic field of the current measuring resistor (1) by energy harvesting, and / or e) Fit the housing cover onto the current measuring resistor (1).

27. The manufacturing method according to claim 22, It is characterized in that The current measuring resistor (1) is used for current measurement in the kA range in a high voltage network, wherein a first connecting part (2), a second connecting part (3) and a resistor element (4) are connected to the current (I AC ) have a circular cross-section in a cross-section at right angles to the flow direction.

28. The manufacturing method according to claim 23, characterized in that: The soldering includes brazing, and the welding includes electron beam welding.

29. The manufacturing method according to claim 23, characterized in that: The brazing includes vacuum brazing.

30. The manufacturing method according to claim 24, characterized in that: Before joining the resistor element (4) to the two connection parts (2, 3), the following steps are performed: The joining surfaces are surface-treated by a coating (5, 6) having nickel, nickel-phosphorus, gold and / or silver as components.

31. The manufacturing method according to claim 25, characterized in that: After joining the resistor element (4) to the two connection parts (2, 3), the following steps are performed: a) shaping the outer contour of the current measuring resistor (1) by turning or milling, a1) making the central resistor element (4) have a larger outer diameter (d2) than the outer connecting parts (2, 3), a2) having a transition contour (7, 8) between the two outer connecting parts (2, 3) with the smaller outer diameter (d1) and the central resistor element (4) with the larger outer diameter (d2), and / or b) Among them, b1) a plurality of flat portions (17) distributed on the circumference of the current measuring resistor (1) are formed on the outer surface of the current measuring resistor (1), and b2) the printed circuit board (18) is bent a number of times according to the number of flat portions (17) and has a plurality of flat printed circuit board sections, and b3) Each flat printed circuit board section is mounted in a plane-parallel manner on a respective one of the flat parts (17) of the current measuring resistor (1).

32. The manufacturing method according to claim 26, characterized in that: The manufacturing method comprises the following steps: a) A printed circuit board (18) for measuring the voltage drop across the resistor element (4) is mounted on the outer surface of the resistor element (4) by means of a fusion welding joint.

Images