Rogowski coil zero region current sensor and design method thereof

Abstract

The invention discloses a Rogowski coil zero-region current sensor and a design method thereof, and relates to the technical field of current sensors, and the Rogowski coil zero-region current sensor comprises a central conductor, an insulating sleeve, a coil skeleton and a coil winding. The insulating sleeve coaxially sleeves the middle part of the central conductor, and the two ends of the central conductor are electric connection ends used for connecting an arc extinguish chamber test loop in series; the coil framework coaxially sleeves the periphery of the insulating sleeve; the coil winding is wound on the coil framework and is used for detecting current; the central conductor is made of a copper alloy material, and the surface of the central conductor is plated with silver; the ratio of the length to the outer diameter of the coil winding is 2-3; the mutual inductance coefficient of the current sensor is 10-50 [mu] H, and the dynamic range of output signals of the signal output end of the coil winding is-10 V to 10 V. The wide dynamic range, the high sensitivity and the broadband characteristics can be considered, and the characteristics of stable structure and good safety are achieved.

Description

Technical Field

[0001] This invention relates to the field of current sensor technology, and in particular to a Rogowski coil zero-zone current sensor and its design method. Background Technology

[0002] In the research and development and testing of high-voltage switchgear, the breaking performance of the arc-extinguishing chamber is a core indicator determining the safety and reliability of the equipment, and the accurate measurement of the zero-zone current is a key means of analyzing the breaking performance of the arc-extinguishing chamber. The zero-zone current encompasses the power frequency fault current before the arc-extinguishing chamber breaks (which can reach tens of thousands of amperes, such as 63kA) and the high-frequency small current after the arc breaks (with an amplitude of only a few hundred milliamperes to several amperes and a frequency as high as 1 to 2 MHz). Its measurement must simultaneously meet the stringent requirements of wide dynamic range, high sensitivity, and wide bandwidth.

[0003] Currently, the mainstream method for measuring the test current of high-voltage switches is the direct measurement method using Rogowski coils. However, the design of conventional Rogowski coils has inherent flaws: to ensure the measurement bandwidth, sensitivity is often sacrificed; conversely, pursuing high sensitivity leads to a narrower bandwidth, creating a contradiction between sensitivity and measurement bandwidth. This contradiction is particularly prominent in zero-zone current measurement, making it difficult for conventional Rogowski coils to achieve the required measurement sensitivity when facing high-frequency, small currents after the arc, and thus difficult to accurately capture subtle changes in the current signal. Furthermore, when measuring large power frequency currents, signal saturation or distortion problems easily occur, severely affecting the accuracy of arc-extinguishing chamber breaking performance analysis and restricting the R&D efficiency and testing reliability of high-voltage switchgear.

[0004] In existing technologies, some improvement solutions attempt to alleviate the aforementioned contradictions by optimizing the coil winding process or selecting special materials, but none of them fundamentally solve the dynamic range adaptability problem. They either cannot cover the full range of measurements from high-frequency power current to low-frequency power current, or their measurement accuracy and stability are insufficient, making it difficult to meet the stringent standards of high-voltage switch tests. Furthermore, existing current sensors have poor mechanical strength and cannot withstand the electrodynamic forces generated by a 63kA power frequency short-circuit current, resulting in significant deformation and displacement, which cannot guarantee the stability of the measurement structure. Moreover, their insulation safety is poor, making it impossible to avoid the risk of insulation breakdown or leakage under high-voltage conditions, and the electrical safety of the testing process cannot be reliably guaranteed.

[0005] Therefore, how to provide a Rogowski coil zero-zone current sensor and its design method that can take into account wide dynamic range, high sensitivity and wide bandwidth characteristics, and has the characteristics of structural stability and good safety is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention proposes a Rogowski coil zero-zone current sensor and its design method, aiming to solve at least one of the above-mentioned technical problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The present invention provides a Rogowski coil zero-zone current sensor, comprising: a center conductor, an insulating sleeve, a coil frame, and a coil winding; The insulating sleeve is coaxially sleeved in the middle of the central conductor, and the two ends of the central conductor are electrical connection terminals for series connection to the arc-extinguishing chamber test circuit; the coil frame is coaxially sleeved on the outer periphery of the insulating sleeve; the coil winding is wound on the coil frame for detecting current; The central conductor is made of copper alloy and silver-plated, with a diameter of 20-30 mm. The ratio of the length to the outer diameter of the coil winding is 2 to 3; The mutual inductance coefficient of the current sensor is 10 to 50 μH, and the dynamic range of the output signal from the signal output terminal of the coil winding is -10V to 10V.

[0009] This invention discloses a Rogowski coil zero-zone current sensor. When used, the two ends of the center conductor are connected in series in the arc-extinguishing chamber test circuit. It can achieve full-range measurement of high-frequency small currents from 63kA at power frequency to 1-2MHz, and from hundreds of milliamps to several amperes. It has a wide dynamic range coverage and comprehensively improved measurement performance, successfully solving the problem that existing sensors are unsuitable for zero-zone current measurement in arc-extinguishing chamber breaking tests due to insufficient dynamic range. The current sensor of this invention has reliable mechanical strength. Its center conductor is optimized and can withstand a 63kA short-circuit current without significant deformation or displacement, and its structural stability meets the requirements of long-term testing. The insulating sleeve ensures the insulation distance between the center conductor and the coil winding, thereby avoiding insulation risks in high-voltage scenarios and ensuring test safety.

[0010] As a further improvement to the above technical solution, the coil winding is a Rogowski coil and is cylindrical, with 1000 to 2000 turns; the wire diameter of the coil winding is 0.1 to 0.2 mm.

[0011] As a further improvement to the above technical solution, the central conductor is a rod with a silver plating thickness of 5-30 μm on its surface; the conductivity of the central conductor is ≥58 mS / m, and its deflection under a 63 kA power frequency short-circuit current is ≤0.1 mm.

[0012] As a further improvement to the above technical solution, the dielectric strength of the insulating sleeve is ≥20kV / mm; the coil frame is cylindrical and its breakdown voltage is ≥30kV.

[0013] As a further improvement to the above technical solution, it also includes an outer shell and a shielding layer; The outer shell has a central through hole, and the insulating sleeve is coaxially inserted through the central through hole; the shielding layer is provided at both ends of the coil winding; the coil frame, the coil winding and the shielding layer are all located inside the outer shell; the shielding layer is connected to the outer shell and grounded.

[0014] As a further improvement to the above technical solution, the outer shell is made of aluminum alloy and has an anodized surface treatment; the shielding effectiveness of the outer shell is ≥40dB.

[0015] As a further improvement to the above technical solution, the current sensor has a frequency range of 50Hz to 2MHz, a current sensitivity of ≥1mV / A, a phase frequency characteristic linearity of ≤±1°, and a signal-to-noise ratio of ≥60dB.

[0016] Another aspect of the present invention provides a design method for a Rogowski coil zero-zone current sensor, comprising the following steps: Step 1: Based on the short-circuit current value to be measured and the conductivity of the center conductor, calculate the electrodynamic force and combine it with mechanical strength verification to determine the material, diameter and surface treatment method of the center conductor; Step 2: Based on the insulation class requirements between the center conductor and the coil winding, and combined with the insulation performance of the insulating bushing, determine the minimum radial insulation distance between the center conductor and the coil winding, and then determine the inner diameter of the coil winding; Step 3: Based on the dynamic range of the zero-zone current and the ±10V output signal requirements of the coil winding in the arc-extinguishing chamber breaking test, derive and calibrate the mutual inductance coefficient of the current sensor through the principle of electromagnetic induction. Step 4: Based on the amplitude and phase frequency characteristics, design the number of turns, wire diameter, length, outer diameter ratio, and winding process of the coil winding; Step 5: Assemble the current sensor and perform performance testing and calibration.

[0017] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a Rogowski coil zero-zone current sensor and its design method, which has the following advantages and beneficial effects.

[0018] 1. The measurement performance of the flow sensor of this invention is comprehensively improved.

[0019] Wide dynamic range coverage: Successfully achieved full-range measurement of high-frequency small currents from 63kA to 1-2MHz and from hundreds of milliamps to several amperes, solving the problem of insufficient dynamic range of existing sensors.

[0020] Excellent sensitivity and frequency characteristics: The sensor has a current sensitivity ≥1mV / A, a frequency band of 50Hz~2MHz, and a phase frequency linearity ≤±1° across the entire measurement range, enabling it to accurately capture subtle changes in zero-zone current and phase information.

[0021] Stable signal output: The dynamic range of the output signal is strictly controlled within ±10V, with no saturation or distortion, and the signal-to-noise ratio is ≥60dB, providing a high-quality signal for subsequent data acquisition and analysis.

[0022] 2. The flow sensor structure of this invention has high reliability and safety.

[0023] Reliable mechanical strength: The central conductor is optimized and does not deform or displace under a short-circuit current of 63kA, and the structural stability meets the requirements of long-term testing.

[0024] Excellent insulation performance: The insulation spacing and material selection between the center conductor and the coil winding are reasonable, and the withstand voltage is ≥10kV, which can avoid insulation risks in high voltage scenarios and ensure test safety.

[0025] 3. The flow sensor of this invention has significant practical value and economic benefits.

[0026] It provides precise data support for the breaking performance analysis of arc-extinguishing chambers, effectively improving the accuracy of fault location during arc-extinguishing chamber R&D and shortening the R&D cycle. It can improve the first-pass yield of high-voltage switch tests, reducing equipment wear, time costs, and labor costs associated with repeated tests. Calculations show that it can reduce product development costs by 15-20%. The sensor has a compact structure and is easy to install, directly adapting to the test circuits of existing 550kV / 63kAGIS equipment without requiring large-scale modifications to the original test system, demonstrating strong versatility. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0028] Figure 1 A schematic diagram of the structure of a Rogowski coil zero-zone current sensor according to the present invention.

[0029] Figure 2 A partial axial cross-sectional schematic diagram of a Rogowski coil zero-zone current sensor according to the present invention.

[0030] In the diagram: 1. Center conductor; 2. Insulating sleeve; 3. Coil frame; 4. Coil winding; 41. Signal output terminal; 5. Outer shell; 6. Shielding layer; 7. Shielding cylinder. Detailed Implementation

[0031] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] According to embodiments of the present invention, such as Figure 1 As shown, a Rogowski coil zero-zone current sensor includes: a center conductor 1, an insulating sleeve 2, a coil frame 3, and a coil winding 4.

[0036] The insulating sleeve 2 is coaxially sleeved in the middle of the center conductor 1. The two ends of the center conductor 1 are electrical connection terminals for series connection to the arc-extinguishing chamber test circuit. The coil frame 3 is coaxially sleeved on the outer circumference of the insulating sleeve 2. The coil winding 4 is wound on the coil frame 3 and is used to detect the current. The center conductor 1 is made of copper alloy and silver-plated, with a diameter of 20-30 mm; The ratio of the length to the outer diameter of coil winding 4 is 2 to 3; The mutual inductance coefficient of the current sensor is 10 to 50 μH, and the dynamic range of the output signal at the signal output terminal 41 of the coil winding 4 is -10V to 10V.

[0037] This embodiment of a Rogowski coil zero-zone current sensor connects the two ends of the center conductor 1 in series within the arc-extinguishing chamber test circuit. It enables full-range measurement of high-frequency small currents from 63kA (power frequency) to 1-2MHz and from hundreds of milliamps to several amperes. The dynamic range is wide, and the measurement performance is comprehensively improved, successfully solving the problem that existing sensors are unsuitable for zero-zone current measurement in arc-extinguishing chamber breaking tests due to insufficient dynamic range. The current sensor of this invention has reliable mechanical strength. Its optimized center conductor 1 can withstand a 63kA short-circuit current without deformation or displacement, and its structural stability meets the requirements of long-term testing. The insulating sleeve 2 ensures the insulation distance between the center conductor 1 and the coil winding 4, thereby avoiding insulation risks in high-voltage scenarios and ensuring test safety.

[0038] In some embodiments, the coil winding 4 is a Rogowski coil and is cylindrical, with 1000 to 2000 turns; the wire diameter of the coil winding 4 is 0.1 to 0.2 mm. The coil winding 4 is coaxially sleeved on the middle of the outer periphery of the insulating sleeve 2.

[0039] In some embodiments, the center conductor 1 is a rod with a silver plating thickness of 5-30 μm on its surface; the conductivity of the center conductor 1 is ≥58 mS / m, and its deflection under a 63 kA power frequency short-circuit current is ≤0.1 mm.

[0040] Specifically, based on the skin effect of alternating current, the silver plating improves the conductivity of the center conductor 1. Furthermore, under high-frequency operating conditions, the silver plating on the surface of the center conductor 1 can bring the current to be measured on the center conductor 1 closer to the coil winding 4, thereby improving the measurement accuracy.

[0041] In some embodiments, the insulating sleeve 2 may be made of epoxy resin and its dielectric strength may be ≥20kV / mm; the coil frame 3 is cylindrical and its breakdown voltage may be ≥30kV.

[0042] In some embodiments, the coil frame 3 is made of polyimide material, which has a temperature resistance of ≥150℃ and a breakdown voltage of ≥30kV, ensuring structural stability and insulation reliability under test conditions.

[0043] In some embodiments, the device further includes a housing 5 and a shielding layer 6.

[0044] The outer shell 5 has a central through hole, and the insulating sleeve 2 is coaxially inserted in the central through hole; both ends of the coil winding 4 are provided with shielding layers 6; the coil frame 3, the coil winding 4 and the shielding layer 6 are all located inside the outer shell 5; the shielding layer 6 is connected to the outer shell 5 and grounded.

[0045] Specifically, the outer shell 5 is cylindrical. The shielding layer 6 is an annular plate, with two shielding layers 6 correspondingly fitted onto the two ends of the insulating sleeve 2 along its length. The shielding layer 6 is made by coating the surface of the annular metal plate with an epoxy resin layer, which serves both as a shield and an insulation function.

[0046] In some embodiments, a shielding cylinder 7 is further included; the shielding cylinder 7 is coaxially disposed inside the housing 5 and sleeved around the outer periphery of the coil winding 4; two shielding layers 6 are correspondingly sealed at the two ends of the shielding cylinder 7 to improve the shielding and insulation effects. The shielding cylinder 7 is made by coating an epoxy resin layer on the surface of a metal cylinder; both shielding layers 6 and the shielding cylinder 7 are electrically connected to the housing 5.

[0047] In some embodiments, the housing 5 is made of aluminum alloy and has an anodized surface; the shielding effectiveness of the housing 5 is ≥40dB.

[0048] In some embodiments, the current sensor has a frequency band of 50Hz to 2MHz, a current sensitivity of ≥1mV / A, a phase frequency linearity of ≤±1°, and a signal-to-noise ratio of ≥60dB.

[0049] Another embodiment of the present invention provides a design method for a Rogowski coil zero-zone current sensor, comprising the following steps: Step 1: Based on the short-circuit current value to be measured and the conductivity of the center conductor 1, calculate the electrodynamic force and combine it with the mechanical strength check to determine the material, diameter and surface treatment of the center conductor; Step 2: Based on the insulation level requirements between the center conductor 1 and the coil winding 4, and combined with the insulation performance of the insulating sleeve 2, determine the minimum radial insulation distance between the center conductor 1 and the coil winding 4, and then determine the inner diameter of the coil winding 4. Step 3: Based on the dynamic range of the zero-zone current and the ±10V output signal requirements of coil winding 4 in the arc-extinguishing chamber breaking test, derive and calibrate the mutual inductance coefficient of the current sensor through the principle of electromagnetic induction. Step 4: Based on the amplitude and phase frequency characteristics requirements, design the number of turns, wire diameter, length, outer diameter ratio, and winding process of coil winding 4; Step 5: Assemble the current sensor and perform performance testing and calibration.

[0050] In some embodiments, in step one, based on the short-circuit current value to be measured (63kA power frequency) and the preset conductivity requirement of the center conductor 1 (copper alloy material, conductivity ≥58MS / m), the magnitude of the electrodynamic force borne by the center conductor 1 when carrying current is calculated by electromagnetic simulation; combined with the mechanical strength verification formula, the diameter range of the center conductor 1 is determined to be 20-30mm to ensure that its deflection under the maximum electrodynamic force is ≤0.1mm, meeting the requirement of no deformation when carrying current; the surface of the center conductor 1 is treated with silver plating, with a plating thickness ≥5μm, to reduce surface resistance and eddy current loss and improve the stability of current transmission.

[0051] In some embodiments, in step two, based on the insulation level requirements (withstand voltage ≥10kV) between the center conductor 1 and the coil winding 4, and combined with the insulation performance parameters of the insulating sleeve 2 (the insulating sleeve 2 is made of epoxy resin with a dielectric strength ≥20kV / mm), the minimum insulation gap is calculated; taking into account the diameter of the center conductor 1 and the minimum insulation gap, the inner diameter of the coil winding 4 of the current sensor is determined, which ensures insulation safety and avoids magnetic field dispersion and sensitivity reduction caused by an excessively large inner diameter.

[0052] Specifically, the inner diameter of the outer casing 5 is larger than the outer diameter of the coil winding 4, and the outer diameter of the outer casing 5 is designed to be 80-100mm.

[0053] In some embodiments, in step three, based on the dynamic range characteristics of the zero-zone current (power frequency, 63kA to 1-2MHz, hundreds of milliamps to several amperes), and combined with the requirement of ±10V for the sensor output signal, the mutual inductance coefficient calculation formula is derived through the principle of electromagnetic induction: M=U / (di / dt) (where U is the output voltage and di / dt is the rate of change of current). Through simulation and experimental verification, the mutual inductance coefficient range of the current sensor is determined to be 10-50μH, ensuring that the output voltage does not exceed 10V in the power frequency high current scenario and is not less than 1mV in the high frequency low current scenario, thus meeting the sensitivity requirements of full-range measurement.

[0054] In some embodiments, in step four, the coil winding 4 is designed with a multi-turn, thin-diameter winding structure, with 1000 to 2000 turns. The length-to-outer diameter ratio of the coil winding 4 is 2 to 3, which can effectively expand the frequency band and ensure a frequency response flatness of ≤ ±0.5dB in the 1 to 2MHz high-frequency range. The conductor of the coil winding 4 is enameled copper wire with a diameter of 0.1 to 0.2mm. It adopts a layered close-winding process with an interlayer insulation thickness ≥ 0.05mm, reducing parasitic capacitance and inductance of the winding and improving frequency characteristics.

[0055] In some embodiments, in step five, the overall structure of the current sensor is assembled as follows: the whole adopts a coaxial structure, with the center conductor 1, insulating sleeve 2, coil frame 3, coil winding 4 and housing 5 arranged coaxially to ensure uniform magnetic field distribution; the housing 5 is made of aluminum alloy and the surface is anodized, which has both electromagnetic shielding and heat dissipation functions, with a shielding effectiveness of ≥40dB, which can effectively resist external electromagnetic interference; shielding layers are set at both ends of the coil winding 4 and connected to the grounding end of the housing to further reduce the influence of interference signals on the measurement results.

[0056] Specifically, the preparation of the center conductor 1: a copper alloy material with a conductivity of 58 mS / m is selected and processed into a cylindrical conductor with a diameter of 25 mm and a length of 300-1000 mm (the length of the center conductor 1 can be designed to be 300 mm or 600 mm). The surface is silver-plated with a silver plating thickness of 5 μm. After mechanical strength testing, its deflection is 0.08 mm under the action of a 63 kA power frequency current, which meets the requirement of no deformation.

[0057] Specifically, the insulating sleeve 2 and the coil bobbin 3 are manufactured as follows: The insulating sleeve 2 is made of epoxy resin, with an inner diameter of 25.2 mm (0.1 mm radial gap with the center conductor 1), an outer diameter of 50 mm, and a length of 300 mm, and a dielectric strength test of ≥25 kV / mm; The coil bobbin is made of polyimide, with an inner diameter of 50.2 mm (0.1 mm gap with the insulating sleeve), an outer diameter of 70 mm, and a length of 250 mm, and a breakdown voltage of ≥30 kV.

[0058] Specifically, the winding of coil winding 4 is as follows: 0.15mm diameter enameled copper wire is selected and wound on coil bobbin 3 using a layered close winding process, with a total of 1500 turns and an interlayer insulation thickness of 0.05mm. The length or height of coil winding 4 is 200mm, the outer diameter is 70mm, and the ratio of the height (or length) to the outer diameter of coil winding 4 is 2.86, which meets the requirements of a slender and tall structure.

[0059] Specifically, mutual inductance coefficient calibration: The mutual inductance coefficient of the current sensor is calibrated using a standard current source. The number of coil turns and winding density are adjusted, and the mutual inductance coefficient is finally determined to be 30μH. The output voltage is 9.5V under a power frequency current of 63kA and 3V under a high frequency and low current of 2MHz and 1A, both within the dynamic range of ±10V.

[0060] Specifically, the overall assembly and testing are as follows: The center conductor 1, insulating sleeve 2, coil winding 4, and coil frame 3 are assembled coaxially in sequence. The two ends of the coil winding 4 are wrapped with shielding layer 6 and electrically connected to the aluminum alloy shell 5. The grounding end of the shell 5 is grounded. The signal output end 41 of the coil winding 4 is connected to the signal input end of the external data acquisition equipment through a signal line. The performance of the assembled current sensor is tested. The results show that the dynamic range covers 50Hz~2MHz, 0.1A~63kA, the sensitivity is 2mV / A, the phase frequency characteristic linearity within the frequency band is ±0.8°, the signal-to-noise ratio is 65dB, and the insulation withstand voltage is 12kV, which meets the design requirements.

[0061] In practical applications, the current sensor of this invention is connected in series to the arc-extinguishing chamber test circuit of a 550kV / 63kAGIS device. The center conductor 1 is reliably connected in series with the test circuit conductor. The signal output terminal 41 of the coil winding 4 is connected to a high-speed data acquisition card (sampling rate ≥10MHz) through a signal line. This enables real-time and accurate measurement of the zero-zone current during the arc-extinguishing chamber interruption process. The measurement data can be directly used for the analysis and evaluation of the arc-extinguishing chamber interruption performance.

[0062] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0063] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A Rogowski coil zero-zone current sensor, characterized in that, include: The center conductor (1), insulating sleeve (2), coil frame (3) and coil winding (4); The insulating sleeve (2) is coaxially sleeved in the middle of the center conductor (1), and the two ends of the center conductor (1) are electrical connection terminals for series connection to the arc-extinguishing chamber test circuit; the coil frame (3) is coaxially sleeved on the outer periphery of the insulating sleeve (2); the coil winding (4) is wound on the coil frame (3) for detecting current; The central conductor (1) is made of copper alloy and silver-plated on the surface, and its diameter is 20-30 mm. The ratio of the length to the outer diameter of the coil winding (4) is 2 to 3; The mutual inductance coefficient of the current sensor is 10 to 50 μH, and the dynamic range of the output signal of the signal output terminal of the coil winding (4) is -10V to 10V.

2. The Rogowski coil zero-zone current sensor according to claim 1, characterized in that, The coil winding (4) is a Rogowski coil and is cylindrical in shape, with 1000 to 2000 turns; the wire diameter of the coil winding (4) is 0.1 to 0.2 mm.

3. The Rogowski coil zero-zone current sensor according to claim 2, characterized in that, The central conductor (1) is a rod with a silver plating thickness of 5-30 μm on its surface; the conductivity of the central conductor (1) is ≥58 mS / m, and its deflection under a 63 kA power frequency short-circuit current is ≤0.1 mm.

4. A Rogowski coil zero-zone current sensor according to claim 3, characterized in that, The dielectric strength of the insulating sleeve (2) is ≥20kV / mm; the coil frame (3) is cylindrical and its breakdown voltage is ≥30kV.

5. A Rogowski coil zero-zone current sensor according to claim 4, characterized in that, It also includes an outer shell (5) and a shielding layer (6); The outer shell (5) has a central through hole, and the insulating sleeve (2) is coaxially inserted in the central through hole; the shielding layer (6) is provided at both ends of the coil winding (4); the coil frame (3), the coil winding (4) and the shielding layer (6) are all located inside the outer shell (5); the shielding layer (6) is connected to the outer shell (5) and grounded.

6. A Rogowski coil zero-zone current sensor according to claim 5, characterized in that, The outer shell (5) is made of aluminum alloy and has an anodized surface; the shielding effectiveness of the outer shell (5) is ≥40dB.

7. A Rogowski coil zero-zone current sensor according to claim 6, characterized in that, The current sensor has a frequency band of 50Hz to 2MHz, a current sensitivity of ≥1mV / A, a phase frequency linearity of ≤±1°, and a signal-to-noise ratio of ≥60dB.

8. A design method for a Rogowski coil zero-zone current sensor as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Based on the short-circuit current value to be measured and the conductivity of the center conductor (1), calculate the electrodynamic force and combine it with the mechanical strength check to determine the material, diameter and surface treatment of the center conductor; Step 2: Based on the insulation level requirements between the center conductor (1) and the coil winding (4), and combined with the insulation performance of the insulating sleeve (2), determine the minimum radial insulation distance between the center conductor (1) and the coil winding (4), and then determine the inner diameter of the coil winding (4); Step 3: Based on the dynamic range of the zero-zone current and the ±10V output signal requirements of the coil winding (4) in the arc-extinguishing chamber breaking test, the mutual inductance coefficient of the current sensor is derived and calibrated by the principle of electromagnetic induction. Step 4: Based on the amplitude and phase frequency characteristics, design the number of turns, wire diameter, length and outer diameter ratio of the coil winding (4) and the winding process; Step 5: Assemble the current sensor and perform performance testing and calibration.

Images