A shielded resistor voltage divider device

Abstract

This invention provides a shielded resistor voltage divider device, comprising: a measuring branch, a shielding branch, and an insulating housing; wherein the measuring branch and the shielding branch are connected in parallel; the measuring branch includes a plurality of high-voltage resistors for measurement and at least one set of low-voltage resistors for measurement connected in series; the shielding branch includes a plurality of high-voltage resistors for shielding and at least one low-voltage resistor for shielding connected in series; the measuring branch and the shielding branch are coaxially arranged inside the insulating housing, and the shielding branch is located outside the measuring branch. In this invention, by coaxially arranging the shielding branch outside the measuring branch, the stray capacitance to ground of the high-voltage resistors used in the measuring branch is greatly reduced, thereby helping to reduce the response time of the voltage divider device; due to the current shunting of the shielding branch, the current in the measuring branch is reduced, which can reduce the heating of the resistance wire and help improve the stability of the scale factor.

Description

Technical Field

[0001] This invention relates to the field of power technology, and more specifically, to a shielded resistor voltage divider device. Background Technology

[0002] Impulse voltage measuring devices are crucial for conducting impulse voltage withstand tests on electrical equipment. Their accuracy directly impacts the safety and economy of power equipment. An effective method to ensure the accuracy and consistency of measurement values ​​is traceability, which uses a continuous chain with specified uncertainty to trace measurement results back to national or international standards. In recent years, with the continuous development of metrology technology, the improvement of quality management systems, and the increasing export volume of measuring equipment from my country, enterprises and research institutes have placed greater emphasis on the traceability of peak and time parameters of impulse measuring equipment. Most equipment users require regular calibration, and quality certification requires verification / calibration certificates from national authoritative institutions. Therefore, establishing national standard measuring devices for impulse voltage in my country is an urgent issue that needs to be addressed.

[0003] Impulse high-voltage dividers are mainly classified into resistive voltage dividers and RC voltage dividers according to their operating principle. RC voltage dividers typically have a high-voltage response time of around 100 ns, which does not meet the high-frequency response characteristics requirements of IEC 60060.2. However, they possess extremely low temperature coefficients and good stability, making resistive voltage dividers more suitable for use as standard voltage divider devices. The high-voltage resistor in a resistive voltage divider is generally a wire-wound resistor. The main factor affecting the high-frequency response characteristics of a resistive voltage divider is stray capacitance to ground. The longer the high-voltage resistor, the larger the stray capacitance to ground, the larger the time constant of the voltage divider device, and the worse the high-frequency response characteristics of the high-voltage device. Therefore, to reduce the length of the high-voltage resistor in a resistive voltage divider, a compressed high-voltage resistor with transformer oil insulation is generally used. However, to maintain the external electric field of the equalizing resistor divider, the higher the voltage, the larger the outer diameter of the resistor divider. Therefore, when the rated voltage of the resistor divider exceeds 1000kV, a segmented resistor divider is generally used. Its high-voltage resistor runs the entire height of the divider, has a small diameter, and the voltage level limitation is mainly due to the insulation of the resistance wire itself. The disadvantage is the high height of the high-voltage resistor and the large stray capacitance to ground. Even with an equalizing ring added at the high-voltage end to compensate for the stray capacitance to ground, the high-frequency response characteristics still cannot meet the standard requirements. Alternatively, the high-voltage resistor can be segmented, with the resistance value gradually decreasing over the same length from the high-voltage end to the ground end, seeking a way to reduce the stray capacitance to ground. Therefore, centralized resistor dividers, due to the increased high-voltage resistor and its short length, have small stray capacitance to ground, and the stray parameter is mainly affected by stray inductance. The disadvantage is the large size of the divider and the high inter-turn voltage of the resistance wire. Distributed resistor dividers have long and thin resistance wires, mainly due to the large impact of stray capacitance to ground. The divider diameter is small, and the inter-turn resistance of the resistance wire is low. The disadvantage is the need to compensate for the impact of stray capacitance to ground. Summary of the Invention

[0004] In view of this, the present invention proposes a shielded resistor voltage divider device, which aims to solve the problem of long response time of existing shielded resistor voltage divider devices.

[0005] In one aspect, the present invention provides a shielded resistor voltage divider device, comprising: a measuring branch, a shielding branch, and an insulating housing; wherein,

[0006] The measuring branch and the shielding branch are connected in parallel;

[0007] The measurement branch includes a plurality of high-voltage resistors for measurement connected in series and at least one set of low-voltage resistors for measurement;

[0008] The shielding branch includes a plurality of high-voltage shielding resistors and at least one set of low-voltage shielding resistors connected in series.

[0009] The measuring branch and the shielding branch are coaxially arranged inside the insulating housing, and the shielding branch is located outside the measuring branch.

[0010] Furthermore, in the above-mentioned shielded resistor voltage divider device, the first end of the measuring high-voltage resistor and the shielding high-voltage resistor at the top is provided with a first connector; the end of the measuring branch high-voltage resistor at the bottom is provided with a second connector, and the end of the shielding high-voltage resistor at the bottom is provided with a third connector.

[0011] The two adjacent high-voltage resistors for measurement located in the middle are connected in series using a fourth connector; the two adjacent high-voltage resistors for shielding located in the middle are connected in series using a fifth connector.

[0012] Furthermore, in the above-mentioned shielded resistor voltage divider device, both the high-voltage resistor for measurement and the high-voltage resistor for shielding are wire-wound resistors, both of which are wound with the same resistance wire and have the same turn spacing.

[0013] Furthermore, in the above-mentioned shielded resistor voltage divider device, the high-voltage resistor for measurement and the high-voltage resistor for shielding are made of double-layer resistance wires, with the lower layer resistance wire wound clockwise and the upper layer resistance wire wound counterclockwise, and the lower layer resistance wire and the upper layer resistance wire are isolated by insulating paper.

[0014] Furthermore, in the aforementioned shielding resistor voltage divider device, the ratio of the high-voltage resistor used for shielding to the high-voltage resistor used for measuring is equal to the ratio of the outer diameter of the insulating support rod for the shielding branch to the outer diameter of the insulating support rod for the measuring branch.

[0015] Furthermore, the aforementioned shielded resistor voltage divider device further includes: a first voltage equalizing ring and multiple second voltage equalizing rings; wherein,

[0016] The first equalizing ring is disposed on the top of the insulating shell, and a second equalizing ring is disposed at the connection point of two adjacent shielding high voltage resistors.

[0017] Furthermore, in the aforementioned shielded resistor voltage divider device, a first insulating inner shell and a second insulating inner shell are also provided inside the insulating outer shell; wherein,

[0018] The first insulating inner shell and the second insulating inner shell are located in the lower region of the interior of the insulating outer shell. They are coaxial with the insulating outer shell, and the second insulating inner shell is located below the first insulating inner shell.

[0019] A low-voltage arm is provided in the first insulating inner shell, and a coaxial cable is provided in the second insulating inner shell.

[0020] Furthermore, in the aforementioned shielded resistor voltage divider device, the low-voltage arm includes: a metal casing and the measuring low-voltage resistor and the shielding low-voltage resistor disposed therein; wherein,

[0021] An insulating cover is provided on the top of the metal casing, and a sixth connector is provided on the top of the insulating cover. The insulating cover is connected to the bottom of the measuring high-voltage resistor through the sixth connector. An internal grounding flange is provided on the bottom of the metal casing.

[0022] Furthermore, the aforementioned shielded resistor voltage divider device also includes: a first flange and a second flange; wherein,

[0023] The first flange is disposed on the top of the insulating shell for crimping the measuring branch and the shielding branch from the top; a hollow columnar body is disposed at the bottom of the first flange, and a plurality of annular grooves are formed on the inner peripheral wall of the hollow columnar body along the axial direction.

[0024] The second flange is located at the bottom of the insulating housing to connect the measuring branch and the shielding branch to external equipment.

[0025] Furthermore, the aforementioned shielded resistor voltage divider device also includes: a damping resistor and a high-voltage conductor; wherein,

[0026] The high-voltage guide rod is disposed at the top inside the insulating shell, and the damping resistor is connected in sequence to the measuring high-voltage resistor and the shielding high-voltage resistor through the high-voltage lead and the high-voltage guide rod.

[0027] An insulating partition is provided between the bottom of the high-voltage guide rod and the top of the measuring branch and the shielding branch.

[0028] Furthermore, the aforementioned shielded resistor voltage divider device further includes: a first matching resistor; wherein,

[0029] One end of the first matching resistor is connected to the high-voltage end of the low-voltage resistor in the measuring circuit, and the other end is connected to the core wire of the coaxial cable inside the insulating shell.

[0030] Furthermore, the aforementioned shielded resistor voltage divider device further includes: a second matching resistor; wherein,

[0031] The second matching resistor is connected in parallel to the end of the coaxial cable inside the insulating housing.

[0032] The shielded resistor voltage divider device of this invention greatly reduces the stray capacitance to ground of the high voltage resistor used in the measurement branch by setting the shielded branch coaxially outside the measurement branch, thereby helping to reduce the response time of the voltage divider device; due to the current shunting of the shielded branch, the current in the measurement branch is reduced, which can reduce the heating of the resistance wire and help improve the stability of the scale factor. Attached Figure Description

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0034] Figure 1 This is a schematic diagram of the shielded resistor voltage divider device provided in an embodiment of the present invention;

[0035] Figure 2 This is another schematic diagram of the shielded resistor voltage divider device provided in an embodiment of the present invention;

[0036] Figure 3 The circuit diagram of the shielded resistor voltage divider device provided in the embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the high-frequency response characteristic test circuit of the shielded resistor voltage divider device provided in an embodiment of the present invention. Detailed Implementation

[0038] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] See Figure 1 The shielded resistor voltage divider device of this invention includes: a measuring branch, a shielding branch, and an insulating housing 1; wherein the measuring branch and the shielding branch are connected in parallel; the measuring branch includes a plurality of high-voltage measuring resistors 2 and at least one set of low-voltage measuring resistors 3 connected in series; the shielding branch includes a plurality of high-voltage shielding resistors 4 and at least one set of low-voltage shielding resistors 5 connected in series; the measuring branch and the shielding branch are coaxially disposed within the insulating housing 1, and the shielding branch is located outside the measuring branch.

[0040] Specifically, the insulating outer shell 1 can be a cylindrical structure, and its height and diameter can be determined according to actual conditions. For example, the height of the insulating outer shell 1 is determined by its rated voltage, which is no less than 3 meters for 1200kV. In this embodiment, the insulating outer shell 1 can be an epoxy fiberglass cylinder.

[0041] There is a gap between the insulating outer shell 1 and the shielded branch, which is filled with insulating oil to increase the insulation strength while dissipating heat.

[0042] Both the measuring branch and the shielding branch can be cylindrical structures. The shielding branch is installed outside the measuring branch, and the two are connected in parallel to form a voltage divider circuit. Theoretically, at the same physical height, the measuring branch and the shielding branch have the same potential, which helps to reduce the stray capacitance to ground of the high voltage resistor on the measuring branch, and thus helps to reduce the response time of the voltage divider device.

[0043] The resistance of the entire voltage divider is the parallel combination of the resistance values ​​of the shielded branch and the measuring branch. Due to the current shunting in the shielded branch, the current in the measuring branch is reduced, which can reduce the heating of the resistance wire. Therefore, the same response can increase the high-voltage resistance of the measuring branch, thereby increasing the rated voltage of the voltage divider. The rated voltage of the resistance voltage divider using this invention can be increased to 1500kV. Compared with the voltage dividers of the prior art with a rated voltage of 1000kV and below, the rated voltage is significantly increased, which can be used for the measurement of impulse steep waves, lightning chopped waves, and lightning full waves, and can be applied to more application scenarios.

[0044] The measurement branch includes multiple high-voltage resistors 2 and at least one low-voltage resistor 3. In this embodiment, there can be four high-voltage resistors 2 and four high-voltage resistors 4 for shielding. Each group of low-voltage resistors 3 and each group of low-voltage resistors 5 for shielding can be formed by multiple low-voltage resistors connected in parallel. The number of low-voltage resistors connected in parallel can be greater than three. For example, each group of low-voltage resistors 3 and each group of low-voltage resistors 5 can be arranged in a circular pattern with four low-voltage resistors spaced apart. The high-voltage resistors 2 and 4 for shielding are coaxially arranged on the upper side inside the insulating shell 1, and the low-voltage resistors 3 and 5 for shielding are coaxially arranged on the lower side inside the insulating shell 1. The multiple high-voltage resistors 2 can be wound sequentially from top to bottom or from bottom to top on the insulating support rod 6 for the measurement branch; the multiple high-voltage resistors 4 for shielding can be wound sequentially from top to bottom or from bottom to top on the insulating support rod 7 for the shielding branch. Each high-voltage resistor for measurement and each high-voltage resistor for shielding are formed by two wire-wound resistors with opposite winding directions connected in parallel. Preferably, the two wire-wound resistors have opposite winding directions, which can reduce stray inductance in the circuit. Multiple high-voltage shielding resistors 4 are sleeved outside the corresponding high-voltage measuring resistors 2, and the two are separated from each other and are not electrically connected.

[0045] The first end of the measuring high-voltage resistor 2 and the shielding high-voltage resistor 4 at the top is provided with a first connector 8; the end of the measuring branch high-voltage resistor at the bottom is provided with a second connector, and the end of the shielding high-voltage resistor 4 at the bottom is provided with a third connector; any two adjacent measuring high-voltage resistors 2 in the middle are connected in series with a fourth connector; any two adjacent shielding high-voltage resistors 4 in the middle are connected in series with a fifth connector.

[0046] Specifically, the first connector 8, the second connector 9, the third connector 10, the fourth connector 11, and the fifth connector 12 can all be copper connectors. The first connector 8 can be a cylindrical structure with an open bottom, and its top cover has several first connection holes circumferentially opened near the center for connecting to the high-voltage measuring resistor 2 via bolts; its lower part has several second connection holes circumferentially opened from the side wall for connecting to the high-voltage shielding resistor 4 via bolts.

[0047] The second connector 9 can be an open-top cylindrical structure with several bolt holes along its horizontal sidewalls and vertical bolt holes on its bottom plate. The second connector 10 can be an annular structure with a hollow column protruding axially upward from its inner ring. The diameter of the hollow column is approximately the same as the diameter of the shielding high-voltage resistor 4. Several vertical bolt holes and horizontal bolt holes are respectively provided on the outer ring edge of the third connector 10 and the circumference of the hollow column. The second connector 9 and the second connector 10 are coaxially arranged and do not contact each other.

[0048] The fourth connector 11 is a cylindrical structure with openings at both ends, and a circular connecting plate is provided inside the cylindrical structure. The fifth connector 12 can also be a cylindrical structure with openings at both ends. Several bolt holes are provided axially on the upper and lower sides of the side walls of the fourth connector 11 and the fifth connector 12. Similarly, the fourth connector 11 and the fifth connector 12 are coaxially arranged and do not contact each other.

[0049] Insulating support blocks 14 are provided at the bottom of the fourth connector 11 and the fifth connector 12. The insulating support rod 6 for the measuring branch and the insulating support rod 7 for the shielding branch are coaxially arranged. Preferably, the insulating shell 1, the insulating support rod 6 for the measuring branch, and the insulating support rod 7 for the shielding branch are coaxially arranged.

[0050] Preferably, the ratio of the high-voltage resistor 4 used for shielding to the high-voltage resistor 2 used for measuring is equal to the ratio of the outer diameter of the insulating support rod 7 used for shielding branch to the outer diameter of the insulating support rod 6 used for measuring branch.

[0051] More specifically, both the high-voltage resistor 2 for measurement and the high-voltage resistor 4 for shielding are wire-wound resistors, both wound with the same resistance wire and with consistent turn spacing. This structure ensures that the points at the same height of the inner and outer resistors are equal, thereby significantly reducing the stray capacitance to ground of the inner high-voltage resistor and improving the high-frequency response characteristics of the voltage conversion branch. An insulating layer is laid on the outside of the resistance wire, and the diameter of the entire resistance wire (including the conductor layer and the insulating layer) is 0.2 mm.

[0052] Furthermore, the high-voltage resistor 2 for measurement and the high-voltage resistor 4 for shielding are made of double-layered resistance wires, with the lower layer wound clockwise and the upper layer wound counterclockwise, and the lower layer and the upper layer are separated by insulating paper. The thickness of the insulating paper can be 0.02-1mm, preferably 0.06mm.

[0053] Multiple high-voltage resistors 2 are connected in series for voltage division, and multiple shields are connected in series for voltage division. When the resistance values ​​of the high-voltage resistors are the same, the heat generated by each resistance wire is lower than that of the resistance wire in an ordinary resistance voltage divider, which can improve the stability of the scale factor.

[0054] Furthermore, the length of the high-voltage resistor in the shielded resistor voltage divider device of the present invention does not need to be compressed, and air insulation or insulating oil insulation can be used. Compared with the compression resistor voltage divider in the prior art, the outer diameter of the device is greatly reduced, which is beneficial to reducing the volume and weight of the voltage divider device. Compared with the segmented resistor voltage divider, the size is almost the same, while the stray capacitance to ground of the measurement branch is reduced, thereby improving the high-frequency response characteristics of the voltage divider device.

[0055] This embodiment also includes: a first flange 15 and a second flange 16; wherein, the first flange 15 is disposed on the top of the insulating housing 1 for crimping the measuring branch and the shielding branch from the top; a hollow cylindrical body is disposed at the bottom of the first flange 15; a plurality of annular grooves are formed axially on the inner peripheral wall of the hollow cylindrical body; the second flange 16 is disposed at the bottom of the insulating housing 1 for connecting the measuring branch and the shielding branch to external equipment. The hollow cylindrical body can be welded to the bottom of the first flange 15. A spring contact finger 18 can be installed in the annular groove.

[0056] Preferably, the bottom of the second flange 16 is provided with several wheels 19 to facilitate moving the pressure-distributing device to the target work site.

[0057] In this embodiment, it may further include: a damping resistor 20 and a high-voltage guide rod 17; wherein, the high-voltage guide rod 17 is disposed at the top inside the insulating shell 1, and the damping resistor is connected to the measuring high-voltage resistor 2 and the shielding high-voltage resistor 4 in sequence through the high-voltage lead 21 and the high-voltage guide rod 17; an insulating partition 22 is disposed between the bottom of the high-voltage guide rod and the top of the measuring branch and the shielding branch.

[0058] Specifically, the diameter of the high-voltage guide rod 17 can be slightly smaller than the diameter of the hollow cylindrical body. The high-voltage guide rod is disposed within the hollow cylindrical body inside the first flange 15. Several spring contacts 18 are sleeved on the high-voltage guide rod, each spring contact being embedded in a corresponding annular groove of the first flange 15 to ensure a tight connection between the high-voltage guide rod and the first flange 15. For example, in this embodiment, two spring contacts are sleeved on the high-voltage guide rod, and the two spring contacts are spaced apart vertically on the high-voltage guide rod. The metal diameter of the spring contacts is determined by the current value, and the material of the spring contacts is a copper alloy with a silver-plated outer layer.

[0059] The insulating partition 22 can be made of epoxy insulating material and is pressed between the top of the high-voltage guide rod and the top of the measuring branch and the shielding branch. A screw is provided at the bottom of the high-voltage guide rod, and the screw passes through the insulating partition 22 to connect to the first connector 8. The insulating partition serves two purposes: firstly, it centers the position of the first connector and the high-voltage guide rod, facilitating the pressing of the high-voltage guide rod to the first flange 15; secondly, it effectively prevents eccentricity between the measuring high-voltage resistor 2 and the shielding high-voltage resistor 4 during installation.

[0060] The insulating partition can be a disc-shaped structure with a connecting hole in the center to facilitate the connection between the high-voltage conductor and the first connecting component. Several oil inlet holes 221 are provided around the circumference of the insulating partition for filling with insulating oil. In practice, the diameter of the insulating partition is slightly smaller than that of the insulating outer shell to facilitate installation.

[0061] See Figure 2 A coaxial cable 30 is also installed inside the insulating housing 1 to facilitate connection with external data acquisition devices. The coaxial cable is located inside the insulating housing, in the area below the low-voltage arm.

[0062] It is evident from the above that this embodiment, by coaxially setting a shielded branch on the outside of the measuring branch, greatly reduces the stray capacitance to ground of the high-voltage resistor used in the measuring branch, thereby helping to reduce the response time of the voltage divider device; due to the current shunting of the shielded branch, the current in the measuring branch is reduced, which can reduce the heating of the resistance wire and help improve the stability of the scale factor.

[0063] Continue reading Figure 1 In the above embodiment, it further includes: a first equalizing ring 23 and a plurality of second equalizing rings 24; wherein, the first equalizing ring 23 is disposed on the top of the insulating shell 1, and a second equalizing ring 24 is disposed at the connection of two adjacent shielding high voltage resistors 4.

[0064] Specifically, the upper end of the first equalizing ring 23 can be connected to the first flange 15. The first equalizing ring 23 is set up to even out the electric field of the voltage distribution device and to compensate for the stray capacitance to ground of the high-voltage resistor 2 for measurement and the high-voltage resistor 4 for shielding. The first equalizing ring 23 is a double-layer equalizing ring, with the outer diameter of the upper ring being smaller than that of the lower ring. For example, the outer diameter of the upper ring is 0.6m and the outer diameter of the lower ring is 1.5m. The vertical height between the two rings can be 0.5m.

[0065] Each second equalizing ring 24 is disposed inside the insulating shell 1, and each second equalizing ring 24 is connected between two adjacent shielding high voltage resistors 4 to equalize the electric field inside the insulating shell 1.

[0066] In the above embodiments, the insulating outer shell 1 is further provided with a first insulating inner shell 25 and a second insulating inner shell 26; wherein, the first insulating inner shell 25 and the second insulating inner shell 26 are located near the lower region inside the insulating outer shell 1, and are coaxial with the insulating outer shell 1 respectively, and the second insulating inner shell 26 is located below the first insulating inner shell 25; a low-voltage arm is provided in the first insulating inner shell 25, and a coaxial cable is provided in the second insulating inner shell 26.

[0067] Specifically, both the first insulating inner shell 25 and the second insulating inner shell 26 are cylindrical structures with equal outer diameters. The height of the first insulating inner shell 25 can be less than the height of the second insulating inner shell 26. A first internal connecting flange 251 is provided at the upper end of the first insulating inner shell 25 to connect the measuring low-voltage resistor 3 and the shielding low-voltage resistor 5 to the measuring branch high-voltage resistor and the shielding high-voltage resistor 4 located at the bottom. A second internal connecting flange 252 is provided at the connection between the bottom of the first insulating inner shell 25 and the second insulating inner shell 26.

[0068] It should be noted that the low-voltage arm 27 includes a metal housing 271 and the measuring low-voltage resistor 3 and the shielding low-voltage resistor 5 disposed therein. The measuring low-voltage resistor 3 and the shielding low-voltage resistor 5 are disposed in the first insulating inner housing 25, which helps to increase their mechanical strength. The measuring high-voltage resistor 2 and the shielding high-voltage resistor 4 are pressed between the measuring low-voltage resistor 3 and the shielding low-voltage resistor 5 and the first equalizing ring 23.

[0069] A coaxial cable is installed in the second insulating inner shell 26 for connecting to external measuring equipment. The installation of the second insulating inner shell 26 can effectively reduce the capacitance to ground of the high-voltage measuring resistor 2 and the high-voltage shielding resistor 4, and provide support for the upper high-voltage measuring resistor and the high-voltage shielding resistor, thereby reducing the pressure exerted by the upper high-voltage measuring resistor and the high-voltage shielding resistor on the low-voltage measuring resistor 3 and the low-voltage shielding resistor 5. On the other hand, by appropriately increasing the height of the high-voltage measuring resistor 2 and the high-voltage shielding resistor 4 from the ground, the stray capacitance to ground of the two resistors can be effectively reduced.

[0070] Furthermore, an insulating cover 28 is provided on the top of the metal casing 271 of the low-voltage arm 27, and a sixth connector 13 is provided on the top of the insulating cover 28. The insulating cover is connected to the bottom of the measuring high-voltage resistor 2 through the sixth connector 13; an internal grounding flange 253 is provided on the bottom of the metal casing.

[0071] Specifically, the sixth connector 13 can be a copper connector. It may include a central disc-shaped structure and two annular structures on either side. A vertical connecting post is located at the top of the disc-shaped structure; the top of the vertical connecting post is connected to the second connector 9. The disc-shaped structure and the annular structure are isolated from each other, coaxially arranged, and electrically independent. Both the disc-shaped structure and the annular structure have several bolt holes circumferentially arranged for connecting the high-voltage and low-voltage measuring resistors, as well as the high-voltage and low-voltage shielding resistors, respectively. A cable connector is provided at the first end of the coaxial cable 30 to connect the coaxial cable to the low-voltage arm 27. One end of the cable is connected to the grounding flange 253 of the low-voltage arm, which is connected above the second internal connecting flange 252. The other end of the cable is connected to the second flange 16. One end of the cable connector 31 is connected to a mounting bracket on the second internal connecting flange 252, and the other end of the cable connector 31 is connected to a mounting bracket on the second flange 16.

[0072] An insulating support block 14 is provided above the first internal connecting flange 251 at the upper end of the first insulating inner shell 25. The sixth connector 13 passes through the insulating support block 14 and is connected to the fourth connector.

[0073] In this embodiment, both the insulating support block 14 and the first internal flange 251 are made of insulating material, which can eliminate the high-frequency oscillations caused by the convergence of the metal conductors at the top of the low-voltage resistor. The third connector 10 and the sixth connector 13 are connected by bolts that pass sequentially through the insulating support block 14 and the first internal flange 251.

[0074] In the above embodiments, O-rings of different sizes are respectively provided at the connection between the insulating outer shell 1 and the first flange 15 and the second flange 16, between the second insulating inner shell 26 and the second flange 16, between the first insulating inner shell 25 and the second insulating inner shell 26, and between the internal grounding flange 253 and the second internal connecting flange 252, for sealing the insulating oil medium.

[0075] See Figure 2 The diagram shows the circuit schematic of a shielded resistor voltage divider. In this voltage divider circuit, the side of the high-voltage resistor is the high-voltage terminal, and the side closer to the low-voltage resistor is the low-voltage terminal. R d For damping resistors, the resistance R 11 R 12 、、R 13 and R 14 For measurement, use high-voltage resistor 2, R 31 For measurement, use low-voltage resistor 3, R 21 R 22 and R 23 and R 24 High-voltage resistor 4, R is used for shielding. 32The point where the low-voltage resistor 5 (for shielding) and the internal low-voltage resistor R21 are connected is the medium-voltage terminal. The low-voltage terminal is grounded; the damping resistor R... d Connected in series before the high-voltage end; the measuring device is connected to the measuring low-voltage resistor R. 31 The two ends.

[0076] Preferably, using coaxial cable to wrap the conductors of the measuring equipment and shielding the measuring equipment with a shielded enclosure can reduce external interference and increase measurement accuracy.

[0077] The above embodiment further includes a first matching resistor 29. One end of the first matching resistor is connected to the high-voltage end of the low-voltage resistor used in the measurement circuit, and the other end is connected to the core wire of the coaxial cable inside the insulating shell, in order to match the wave impedance of the cable and reduce waveform oscillations caused by internal reflections in the cable. In practice, one end of the first matching resistor is connected to the sixth connector 13, and the other end is connected to the coaxial cable 30. In this embodiment, when only the first matching resistor 29 is used, the low-voltage resistance of the shielded branch = the low-voltage resistance of the measurement branch × the ratio of the outer diameter of the insulating support rod for the shielded branch to the outer diameter of the insulating support rod for the measurement branch.

[0078] Preferably, the above embodiment may further include a second matching resistor 32, which is connected in parallel to the end of the coaxial cable inside the insulating shell, to further match the wave impedance of the cable and reduce waveform oscillations caused by internal reflections within the cable. In this embodiment, if the low-voltage resistance of the measuring branch is equal to the wave impedance of the cable, only the second matching resistor needs to be connected in parallel at the end of the cable. When only the second matching resistor 32 is present, the low-voltage resistance of the shielded branch = the parallel resistance of the low-voltage resistance of the measuring branch and the second matching resistor × the ratio of the outer diameter of the insulating support rod for the shielded branch to the outer diameter of the insulating support rod for the measuring branch.

[0079] As a preferred embodiment, this embodiment includes both a first matching resistor 29 and a second matching resistor 32, such as... Figure 3 As shown, the first matching resistor is R. M1 The second matching resistor is R M2 The low-voltage resistance of the shielded branch is equal to the ratio of the outer diameter of the insulating support rod for the shielded branch to the outer diameter of the insulating support rod for the measuring branch.

[0080] See Figure 4A step wave response test was conducted on the shielded resistor voltage divider device in this embodiment of the invention. A square wave source output a square wave voltage with a rise time of less than 5ns, which was connected to the first end of the voltage divider device. The ground of the square wave source and the ground of the voltage divider device were connected using a grounding copper foil. The output signal of the measurement cable of the voltage divider device was connected to a data acquisition device. The square wave response waveform of the voltage divider device was displayed on the data acquisition device. The high-frequency response characteristics of the voltage divider device could be obtained by calculating the parameters of the square wave response waveform. During the test, the overall equivalent resistance of the voltage divider device was the parallel connection of the shielding branch resistance and the measurement branch resistance. The equivalent capacitance was the first equalizing ring and the stray capacitance of the shielding branch to ground. The actual measurement showed that the response time was 85ns when only the test branch was used. After adding the shielding branch, the response time decreased to 25ns, indicating that adding the shielding branch greatly shortened the response time of the voltage divider device.

[0081] The specific implementation of the present invention is described using a 1200kV shielded resistor voltage divider device as an example.

[0082] The insulating outer shell 1 has a height of 3500mm and an outer diameter of 260mm, and the internal insulating medium is insulating oil.

[0083] The high-voltage resistor 2 for measuring the voltage divider and the high-voltage resistor 4 for shielding are made of 0.2mm Kamah wire. The insulating support rod for the measuring branch resistor is made of nylon, with each section being 700mm high and 45mm in outer diameter, and each resistor having a resistance of 3 kΩ. The insulating support rod for the shielding resistor is made of nylon, with each section being 700mm high and 75mm in outer diameter, and each resistor having a resistance of 5kΩ.

[0084] The measuring low-voltage resistor 3 and the shielding low-voltage resistor 5 are made of multiple non-inductive thick-film resistors connected in parallel. The measuring low-voltage resistor is 315Ω, the shielding low-voltage resistor is 525Ω, the first matching resistor is 35Ω, and the measurement is performed using a cable with a wave impedance of 50Ω.

[0085] The damping resistor is a wire-wound resistor with a resistance of 130Ω, a diameter of 24mm, and a length of 200mm.

[0086] The first connecting piece 8, the second connecting piece 9, the third connecting piece 10, the fourth connecting piece 11, the fifth connecting piece 12, and the sixth connecting piece 13 are made of brass. The metal connecting screws that pass through each connecting piece are brass countersunk screws. The connecting screws of the first flange 15 and the second flange 16 at the upper and lower ends of the insulating shell 1 are stainless steel internal hexagonal screws.

[0087] In summary, the shielded resistor voltage divider device provided by this invention significantly reduces the stray capacitance to ground of the high-voltage resistor in the measuring branch by coaxially arranging the shielded branch outside the measuring branch, thereby reducing the response time of the voltage divider device. Due to the current shunting in the shielded branch, the current in the measuring branch is reduced, which decreases the heating of the resistance wire and improves the stability of the calibration factor. The length of the high-voltage resistor in the shielded device does not need to be compressed; air insulation or insulating oil insulation can be used. Compared with the compression-type resistor voltage dividers in the prior art, the outer diameter of the device is significantly reduced, which helps to reduce the size and weight of the voltage divider device. Compared with the segmented resistor voltage divider, while maintaining similar dimensions, the stray capacitance to ground of the measuring branch is reduced, thereby improving the high-frequency response characteristics of the voltage divider device. The equivalent resistance of the voltage divider device is the parallel resistance of the measuring branch and the shielded branch resistances; therefore, for the same response, the high-voltage resistance of the measuring branch can be increased, thereby increasing the rated voltage of the voltage divider device.

[0088] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A shielded resistance voltage dividing device, characterized by comprising: include: Measurement branch, shielded branch, and insulating housing; among which, The measurement branch and the shielding branch are connected in parallel; The measurement branch includes a plurality of high-voltage resistors for measurement connected in series and at least one set of low-voltage resistors for measurement; The shielding branch includes a plurality of high-voltage shielding resistors and at least one set of low-voltage shielding resistors connected in series. The measuring branch and the shielding branch are coaxially arranged inside the insulating housing, and the shielding branch is located outside the measuring branch; The plurality of high-voltage resistors for measurement are wound sequentially from top to bottom or from bottom to top on the insulating support rod for the measurement branch; the high-voltage resistors for shielding are wound sequentially from top to bottom or from bottom to top on the insulating support rod for the shielding branch; the ratio of the plurality of high-voltage resistors for shielding to the high-voltage resistors for measurement is equal to the ratio of the outer diameter of the insulating support rod for the shielding branch to the outer diameter of the insulating support rod for the measurement branch. The first ends of the measuring high-voltage resistor and the shielding high-voltage resistor at the top are provided with a first connector; The top of the insulating shell is provided with a first flange, and the top of the interior of the insulating shell is provided with a high-voltage guide rod; the first flange is connected to the first connector through the high-voltage guide rod; an insulating partition is provided between the bottom of the high-voltage guide rod and the first connector.

2. The shielded resistor voltage divider device according to claim 1, characterized in that, A second connector is provided at the end of the high-voltage resistor of the measuring branch at the bottom, and a third connector is provided at the end of the high-voltage resistor for shielding at the bottom. The two adjacent high-voltage resistors for measurement located in the middle are connected in series using a fourth connector; the two adjacent high-voltage resistors for shielding located in the middle are connected in series using a fifth connector.

3. The shielded resistor voltage divider device according to claim 1, characterized in that, Both the high-voltage resistor used for measurement and the high-voltage resistor used for shielding are wire-wound resistors, both made with the same resistance wire and with the same turn spacing.

4. The shielded resistor voltage divider device according to claim 3, characterized in that, The high-voltage resistor for measurement and the high-voltage resistor for shielding are made of double-layered resistance wires, with the lower layer of resistance wire wound clockwise and the upper layer of resistance wire wound counterclockwise, and the lower layer of resistance wire and the upper layer of resistance wire are isolated by insulating paper.

5. The shielded resistor voltage divider device according to claim 1, characterized in that, Also includes: A first equalizing ring and multiple second equalizing rings; wherein... The first equalizing ring is disposed on the top of the insulating shell, and a second equalizing ring is disposed at the connection point of two adjacent shielding high voltage resistors.

6. The shielded resistor voltage divider device according to claim 1, characterized in that, The insulating outer shell also includes a first insulating inner shell and a second insulating inner shell; wherein... The first insulating inner shell and the second insulating inner shell are located in the lower region of the interior of the insulating outer shell. They are coaxial with the insulating outer shell, and the second insulating inner shell is located below the first insulating inner shell. A low-voltage arm is provided in the first insulating inner shell, and a coaxial cable is provided in the second insulating inner shell.

7. The shielded resistor voltage divider device according to claim 6, characterized in that, The low-voltage arm includes: a metal housing and the measuring low-voltage resistor and the shielding low-voltage resistor disposed therein; wherein, An insulating cover is provided on the top of the metal casing, and a sixth connector is provided on the top of the insulating cover. The insulating cover is connected to the bottom of the measuring high-voltage resistor through the sixth connector. An internal grounding flange is provided on the bottom of the metal casing.

8. The shielded resistor voltage divider device according to claim 1, characterized in that, Also includes: Second flange; among which, The first flange is disposed on the top of the insulating shell for crimping the measuring branch and the shielding branch from the top; a hollow columnar body is disposed at the bottom of the first flange, and several annular grooves are formed on the inner peripheral wall of the hollow columnar body along the axial direction. The second flange is located at the bottom of the insulating housing to connect the measuring branch and the shielding branch to external equipment.

9. The shielded resistor voltage divider device according to claim 1, characterized in that, Also includes: Damping resistor; where, The damping resistor is connected in sequence to the measuring high-voltage resistor and the shielding high-voltage resistor via a high-voltage lead and the high-voltage conductor.

10. The shielded resistor voltage divider device according to claim 1, characterized in that, Also includes: The first matching resistor; where, One end of the first matching resistor is connected to the high-voltage end of the low-voltage resistor in the measuring circuit, and the other end is connected to the core wire of the coaxial cable inside the insulating shell.

11. The shielded resistor voltage divider device according to claim 1 or 10, characterized in that, Also includes: The second matching resistor; where, The second matching resistor is connected in parallel to the end of the coaxial cable inside the insulating housing.

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