An inductive voltage divider supporting cascade connection

Abstract

An inductive voltage divider supporting cascade connection is characterized in that the inductive voltage divider includes an input interface, an output interface, an excitation winding, a proportional winding, and a housing; wherein the proportional winding is a hollow annular body that accommodates the solid annular excitation winding, and a through hole is opened on the outer side of the hollow annular body, and the input interface is arranged on the through hole to connect the tap of the excitation winding to the inner and outer conductors of the input interface; the output interface is provided on the opposite side of the input interface, and the ends of both are fixedly connected to the housing to achieve internal sealing of the inductive voltage divider; the housing is annular and wraps around the outer side of the proportional winding. The housing is provided with a fine-tuning knob and a gear selection button, which are connected to the tap of the proportional winding in sequence and indirectly connect the tap of the proportional winding to the inner and outer conductors of the output interface. The inductive voltage divider of the present invention is safe and reliable, with high precision and long service life.

Description

Technical Field

[0001] The present invention relates to the field of electrical equipment, and more particularly to an inductive voltage divider supporting cascade connection. Background Art

[0002] At present, with the continuous development of the power system, the scale and configuration pattern of electric energy transmission are becoming increasingly large. my country's ultra-high voltage DC power grid has now reached a voltage level of 800kV, and ultra-high voltage AC has reached a voltage level of 1000kV, capable of large-capacity long-distance power transmission.

[0003] The measurement accuracy of AC voltage in power grids is a crucial indicator for energy metering, equipment operation and maintenance, and fault monitoring. Therefore, calibration of AC voltage measuring instruments is essential. Currently, the most commonly used method for measuring instrument calibration is traceability. This is a chain of comparisons between various levels of uncertainty. The measured object is traced back to a measurement standard with higher accuracy, thereby quantifying its own accuracy. Voltage ratio standards are key tools for traceability and are widely used in the calibration and verification of measuring instruments.

[0004] Commonly used voltage ratio standard devices are mainly voltage dividers, including resistor voltage dividers, active voltage dividers and inductive voltage dividers. When used for high voltage calibration measurement, resistor voltage dividers are easily affected by various factors, mainly resistance heating, which limits their stability. Although active voltage dividers have the advantages of simple structure and flexible ratio, they are easily affected by the external environment and power supply, making them difficult to work in complex environments. Compared with the first two devices, inductive voltage dividers have higher accuracy and more mature manufacturing processes, with an accuracy of 10 -7 Magnitude.

[0005] At present, the inductive voltage dividers developed by various research institutions include: the 600V seven-disc inductive voltage divider developed by the China Institute of Metrology, whose overall error is better than 1×10 -7 The 1kV multi-disc broadband inductive voltage divider developed by the Australian Institute of Metrology has a measurement frequency range of 40 to 100 Hz and a broadband error of better than 1×10 -6 .

[0006] However, the aforementioned inductive voltage divider also has its drawbacks. First, due to inherent flaws in the manufacturing process, the wound coils cannot be absolutely evenly distributed around the core. Consequently, there is an error between the actual output voltage and the designed theoretical output voltage, which is difficult to compensate for. Second, when used in high-voltage environments and connected to AC lines, inductive voltage dividers are susceptible to external electromagnetic radiation, which can easily cause AC signal transmission radiation losses. Furthermore, when performing high-ratio voltage division, it is often necessary to cascade several inductive voltage dividers. The errors in each individual stage accumulate after cascading, resulting in even greater errors. Furthermore, a multi-stage structure creates a heavy load on the power supply under test, further limiting the measuring range of the inductive voltage divider.

[0007] In view of the above problems, a new cascade-supporting inductive voltage divider is urgently needed. Summary of the Invention

[0008] In order to address the deficiencies in the prior art, the present invention provides an inductive voltage divider that supports cascading, in which the inductive voltage divider is sequentially implemented with a ring-shaped excitation winding, a proportional winding and a disc-shaped shell in a sleeve manner, and the input interface and the output interface are integrated inside the shell, thereby accurately realizing the structure of the inductive voltage divider.

[0009] The present invention adopts the following technical solutions.

[0010] The first aspect of the present invention relates to an inductive voltage divider supporting cascade, the inductive voltage divider comprising an input interface, an output interface, an excitation winding, a proportional winding and a shell; wherein the proportional winding is a hollow annular body, which accommodates the excitation winding in the shape of a solid annular body, and a through hole is opened on the outer side of the hollow annular body, and the input interface is arranged on the through hole to connect the tap of the excitation winding with the inner and outer conductors of the input interface; the output interface is arranged on the opposite side of the input interface, and the ends of both are fixedly connected to the shell to achieve internal closure of the inductive voltage divider; the shell is annular and wrapped around the outside of the proportional winding, and a fine-tuning knob and a gear selection button are provided on the shell, which are connected to the tap of the proportional winding in sequence, and the tap of the proportional winding is indirectly connected to the inner and outer conductors of the output interface.

[0011] Preferably, the input interface and the output interface are both cylindrical, and the ends of the cylinders are fixedly connected to the outer side of the circular ring of the shell; the physical axes of the input interface and the output interface coincide, pass through the geometric center of the shell, and are perpendicular to the axis of the shell.

[0012] Preferably, the excitation winding and the proportional winding both include an iron core and a winding conductor wound on the iron core; wherein the iron core is a silicon steel sheet and the winding conductor is a copper cable; and the interior of the iron core of the proportional winding is coated with insulating varnish.

[0013] Preferably, the head tap and the end tap of the wound wire in the excitation winding are respectively connected to the inner conductor and the outer conductor of the input interface; and the cylindrical surface of the input interface is provided with an insulating sheath so that the input interface passes through the shell and the proportional winding and is connected to the tap of the excitation winding in an externally insulated manner.

[0014] Preferably, the proportional winding realizes the gear division of the winding wire based on the binary proportional method; all taps on the winding wire divided into the current gear are led out from the proportional winding and uniformly welded on the fine-tuning knob.

[0015] Preferably, the fine-tuning knob includes an arc-shaped stator and a pointer-shaped movable piece; wherein, one end of the pointer-shaped movable piece is fixed on the center of the arc-shaped stator, and is rotated by a stud of the fine-tuning knob which is also arranged on the center of the circle so that the other end of the pointer-shaped movable piece contacts different positions of the arc-shaped stator; and, the stud of the fine-tuning knob and one end of the arc-shaped stator are connected to the gear button through a wire; and the head end of the arc-shaped stator is connected to the outer conductor of the output interface through a first wire.

[0016] Preferably, the other end of one end of the gear button is connected to the inner conductor of the output interface through a second wire; the conduction button is a line switch.

[0017] Preferably, the inductive voltage divider includes a plurality of fine-tuning knobs and a plurality of gear buttons of equal number; and a plurality of first wires are connected in parallel to the outer conductor of the output interface, and a plurality of second wires are connected in parallel to the inner conductor of the output interface.

[0018] Preferably, the input interface and the output interface are provided with an inner conductor, an insulating gasket, an outer conductor and an insulating sheath of a coaxial interface in sequence from the inside to the outside.

[0019] Preferably, the exterior of the insulating sheath is a smooth structure or a threaded structure; the inductive voltage divider further comprises an internally threaded pipe fitting, the internal thread of the internally threaded pipe fitting being coupled with the threaded structure of the insulating sheath to achieve cascading of multiple inductive voltage dividers; the smooth structure of the insulating sheath is coupled with the wiring terminal of the coaxial cable to achieve connection between the inductive voltage divider and the AC voltage divider circuit.

[0020] Preferably, a plurality of fine-tuning knobs and gear buttons are arranged in parallel and at equal intervals on the outer wall of the top surface of the shell; the shell is made of brass material, and the inner surface is sprayed with insulating paint. The position where the input interface and the output interface are fixedly connected is a threaded hole coupled with the threaded interface of the insulating sheath.

[0021] The beneficial effects of the present invention are that, compared with the prior art, the cascade-supporting inductive voltage divider of the present invention can sequentially implement a circular excitation winding, a proportional winding, and a disc-shaped housing through a sleeve arrangement, and integrate the input and output interfaces within the housing, thereby precisely implementing the structure of the inductive voltage divider. The inductive voltage divider of the present invention has a simple, safe, and reliable structure, minimizes line access errors and cascade line resistance errors, fully prevents external electromagnetic radiation in high-voltage environments, and has high measurement accuracy, strong reliability, and a long service life.

[0022] The beneficial effects of the present invention also include:

[0023] 1. The present invention arranges all windings in an inductive voltage divider in a circular manner, so that the arrangement of the windings is sufficiently uniform and the mutual induction process is very accurate, ensuring the minimum error between the actual output value and the theoretical value.

[0024] 2. The present invention utilizes a brass structure to manufacture the inductive voltage divider housing and positions the excitation element within the proportional winding. These elements are fully isolated by an insulating layer, effectively shielding the inductive voltage divider from external electromagnetic radiation interference in high-voltage environments and when connected to AC lines. Furthermore, since the input and output interfaces are also isolated and hermetically connected to the housing, proportional winding, and other components, transmission losses during AC signal transmission are effectively prevented.

[0025] 3. The inductive voltage divider in the present invention can simultaneously support the cascade between multiple voltage dividers. Through the overall disc-shaped structure, the error caused by the line resistance of the input and output interfaces to the measurement is minimized. At the same time, the internal threaded tube is cleverly designed to match the shape of the input and output interfaces, expanding the application scenarios, range and measurement accuracy of the inductive voltage divider, ensuring radiation shielding during the AC voltage transmission process, and ensuring the accuracy of the measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the overall structure of an inductive voltage divider supporting cascade connection according to the present invention;

[0027] Figure 2 A schematic cross-sectional view of a toroidal winding in an inductive voltage divider supporting cascade connection according to the present invention;

[0028] Figure 3 This is a schematic diagram of the internal structure of a fine-tuning knob in an inductive voltage divider supporting cascade according to the present invention;

[0029] Figure 4 This is a schematic diagram of the proportional winding output line in an inductive voltage divider supporting cascade connection according to the present invention;

[0030] Figure 5The figure is a schematic diagram of the connection mode of the input and output interfaces of an inductive voltage divider supporting cascade in the present invention. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in the present invention are only part of the embodiments of the present invention, not all of the embodiments. Based on the spirit of the present invention, all other embodiments not described in the present invention that are obtained by ordinary technicians in this field based on the embodiments described in the present invention without making creative work should fall within the scope of protection of the present invention.

[0032] Figure 1 This is a schematic diagram of the overall structure of an inductive voltage divider supporting cascade connection in the present invention. Figure 1 As shown, the present invention relates to an inductive voltage divider supporting cascade, the inductive voltage divider comprising an input interface, an output interface, an excitation winding, a proportional winding and a shell; wherein the proportional winding is a hollow annular body, which accommodates the excitation winding in the shape of a solid annular body, and a through hole is opened on the outer side of the hollow annular body, and the through hole is arranged with an input interface to connect the tap of the excitation winding with the inner and outer conductors of the input interface; the output interface is arranged on the opposite side of the input interface, and the ends of both are fixedly connected to the shell to realize the internal closure of the inductive voltage divider; the shell is annular and wrapped around the outside of the proportional winding, and a fine-tuning knob and a gear selection button are provided on the shell, which are connected to the tap of the proportional winding in sequence, and the tap of the proportional winding is indirectly connected to the inner and outer conductors of the output interface.

[0033] In the present invention, a proportional winding and an excitation winding are provided through a circular ring structure, which makes it possible to simply and fully ensure the uniform distribution of the windings and the accuracy of the two sets of windings when cooperating to achieve electromagnetic induction during the manufacturing process of the inductive voltage divider, and reduces the manufacturing cost of the windings. Regardless of the working state, the winding part of the proportional winding connected between the high and low voltages can achieve corresponding mutual inductance with the excitation winding corresponding to it, thereby achieving accurate output. It can be seen that this method effectively compensates for the inherent defects caused by the winding process, adopts a two-stage combination structure, and when the proportional winding and the iron core are working, the excitation winding and the iron core are excited, so that the iron core is accelerated to magnetize while reducing the excitation current, greatly improving the input impedance of the inductive voltage divider and reducing the magnetic error.

[0034] Preferably, the input interface and the output interface are both cylindrical, and the ends of the cylinders are fixedly connected to the outer side of the circular ring of the shell; the physical axes of the input interface and the output interface coincide, pass through the geometric center of the shell, and are perpendicular to the axis of the shell.

[0035] The input and output interfaces in this invention are both cylindrical, which increases the volume of the internal and external wires within the interface, thereby reducing the impact of the interface impedance on the measurement. Furthermore, the two interfaces are located on opposite sides, which is not only convenient for use but also facilitates the cascading of multiple sensors.

[0036] Preferably, the excitation winding and the proportional winding both include an iron core and a winding conductor wound on the iron core; wherein the iron cores C1 and C2 are silicon steel sheets, and the winding conductors W1 and W2 are copper cables; the interior of the iron core of the proportional winding is coated with insulating varnish.

[0037] It is understood that the excitation winding and proportional winding in the present invention can be manufactured from silicon steel sheets and copper cables. To ensure insulation between the two cores C1 and C2 under the excitation of high-voltage AC, the present invention applies an insulating varnish to the interior of core C2 for insulation. Due to the sheathing arrangement of C1 and C2, the excitation core C1 can transfer the magnetic field to C2, thereby generating an AC voltage on the proportional winding.

[0038] Figure 2 FIG. 1 is a cross-sectional diagram of a toroidal winding in a cascade-supporting inductive voltage divider according to the present invention. Figure 2 As shown, in one embodiment of the present invention, C1 is a solid annular structure with an outer radius of 10 cm, an inner radius of 7 cm, and an annular cross-section diameter of 6 cm. C2 is a hollow annular structure with an outer radius of 15 cm, an inner radius of 12 cm, and an annular cross-section diameter of 10 cm.

[0039] Preferably, the head tap and the end tap of the wound wire in the excitation winding are respectively connected to the inner conductor and the outer conductor of the input interface; and the cylindrical surface of the input interface is provided with an insulating sheath so that the input interface passes through the shell and the proportional winding and is connected to the tap of the excitation winding in an externally insulated manner.

[0040] In the present invention, the input interface can be connected to the first and last taps of the excitation winding, thereby ensuring that the AC voltage at the input end is input into the excitation winding, thereby achieving excitation. In addition, the output interface can be optionally connected to one or more sets of taps in the proportional winding, thereby achieving proportional voltage output.

[0041] Preferably, the proportional winding realizes the gear division of the winding wire based on the binary proportional method; all taps on the winding wire divided into the current gear are led out from the proportional winding and uniformly welded on the fine-tuning knob.

[0042] It can be understood that the method of the present invention can realize the distribution of different proportions for proportional windings. In one embodiment of the present invention, after W2 is wound, the winding taps within the proportional range of 1 / 2±1 / 256, 1 / 4±1 / 256, 1 / 8±1 / 256, 1 / 16±1 / 256, 1 / 32±1 / 256, 1 / 64±1 / 256, 1 / 128±1 / 256, 1 / 256±1 / 256 are all led out to realize gear division. It should be noted that the proportional range here can be divided according to the percentage of the actual length of the winding. The binary ratio here is the one that can divide 1 / 2, 1 / 2 2 ,……,1 / 2 n-1 , 1 / 2 n The winding is divided into multiple sections according to the total length. Parameter n represents the winding division level and can correspond to the voltage division accuracy of the inductive voltage divider, as well as the number of fine-tuning knobs and gear buttons of the inductive voltage divider. The present invention can select the value of parameter n based on actual needs. In the above embodiment, its value is 8.

[0043] It should be noted that each winding division level may include multiple taps. By means of multiple taps, the present invention can achieve fine-tuning of the actual winding ratio at each division level.

[0044] Figure 3 This is a schematic diagram of the internal structure of a fine-tuning knob in a cascade-supporting inductive voltage divider of the present invention. Figure 3 As shown, preferably, the fine-tuning knob includes an arc-shaped stator and a pointer-shaped movable piece; wherein, one end of the pointer-shaped movable piece is fixed on the center of the arc-shaped stator, and is rotated by a stud of the fine-tuning knob which is also arranged on the center of the circle so that the other end of the pointer-shaped movable piece contacts different positions of the arc-shaped stator; and, the stud of the fine-tuning knob and one end of the arc-shaped stator are connected to the gear button through a wire; and the head end of the arc-shaped stator is connected to the outer conductor of the output interface through a first wire.

[0045] It is understood that the fine-tuning knob of the present invention is arranged on the housing and can be rotated by the fine-tuning knob outside the housing. A fine-tuning knob stud is connected below the knob, and the lower half of the stud and other mechanical structures connected to the fine-tuning knob are located inside the housing.

[0046] Specifically, if Figure 3As shown, multiple taps divided into a level can be uniformly welded to the copper stator in a sequential manner. The rotor rotates with the fine-tuning knob. By changing the position of the contact point between the rotor and the stator, the present invention can adjust the proportional voltage output by the inductive voltage divider. Inside the knob, the head end of the stator is connected to a lower potential. In the present invention, this can be achieved by connecting to the inner conductor of the output interface. Alternatively, the corresponding gear button can be connected to one end of the rotor to achieve access to a tap at a certain position on the stator.

[0047] Figure 4 This is a schematic diagram of the proportional winding output line in a cascade-supported inductive voltage divider of the present invention. Figure 4 As shown, the other end of one end of the gear button is connected to the inner conductor of the output interface through a second wire; the conduction button is a line switch.

[0048] It is understood that the various taps in the present invention can be indirectly connected to the gear button via a fine-tuning knob. The gear button can function as a circuit switch by being pressed or released. When multiple gear buttons are in the closed state, parallel output of multiple taps can be achieved.

[0049] In an embodiment of the present invention, according to the design ratio of the tap in the foregoing text, the gears available for user selection include 1 / 2 gear, 1 / 4 gear, 1 / 8 gear, 1 / 16 gear, 1 / 32 gear, 1 / 64 gear, 1 / 128 gear, and 1 / 256 gear.

[0050] Preferably, the inductive voltage divider includes a plurality of fine-tuning knobs and a plurality of gear buttons of equal number; and a plurality of first wires are connected in parallel to the outer conductor of the output interface, and a plurality of second wires are connected in parallel to the inner conductor of the output interface.

[0051] It is understandable that an equal number of gear buttons and fine-tuning knobs are respectively provided on the housing of the inductive voltage divider. Due to the wiring method described above, the AC voltage detection range of the inductive voltage divider of the present invention can be further improved.

[0052] Preferably, the input interface and the output interface are provided with an inner conductor, an insulating gasket, an outer conductor and an insulating sheath of a coaxial interface in sequence from the inside to the outside.

[0053] Figure 5 This is a schematic diagram of the connection mode of the input and output interfaces of a cascade-supporting inductive voltage divider of the present invention. Figure 5 As shown, the input interface and output interface of the present invention can be implemented by using a coaxial structure, which is provided with a conductor layer and an insulating layer from the inside to the outside.

[0054] Preferably, the exterior of the insulating sheath is a smooth structure or a threaded structure; the inductive voltage divider further comprises an internally threaded pipe fitting, the internal thread of the internally threaded pipe fitting being coupled with the threaded structure of the insulating sheath to achieve cascading of multiple inductive voltage dividers; the smooth structure of the insulating sheath is coupled with the wiring terminal of the coaxial cable to achieve connection between the inductive voltage divider and the AC voltage divider circuit.

[0055] It is understood that both the inner and outer conductors in the present invention are made of gold-plated copper. The outer conductor is a hollow cylindrical metal tube, which transmits low-level signals and serves as a shield in the transmission loop. The inner conductor is a solid cylindrical metal body, which transmits high-level signals in the transmission loop. The coaxial structure confines the electromagnetic field generated by the AC transmission between the inner and outer conductors, effectively reducing radiation losses.

[0056] An insulating gasket serves as support material between the inner and outer conductors. The outermost layer has two structures: a conventional structure, where the outer insulating sheath is connected to the coaxial cable and the power supply under test, and the inner thread is installed into the inductive voltage divider housing and connected to the inner core; the other is a cascade structure, where both the inner and outer threads are threaded, and threaded pipes are used to connect the input and output interfaces of different inductive voltage dividers to form a cascade.

[0057] Preferably, a plurality of fine-tuning knobs and gear buttons are arranged in parallel and at equal intervals on the outer wall of the top surface of the shell; the shell is made of brass material, and the inner surface is sprayed with insulating paint. The position where the input interface and the output interface are fixedly connected is a threaded hole coupled with the threaded interface of the insulating sheath.

[0058] In this invention, eight gear selection buttons and eight fine-tuning knobs are arranged parallel to each other on the upper surface of the housing. The housing is constructed of brass and has an open-top structure. Its upper surface serves as a cover, and its inner and outer surfaces are sprayed with insulating varnish. Threaded holes are drilled in its outer wall to provide access to its inner surface. An inductive voltage divider core is placed and secured within the housing. The core's input and output are connected to the input / output interface using coaxial wires.

[0059] When using the inductive voltage divider of the present invention, one first determines the ratio range to be adjusted, presses the corresponding gear selection button, connects the voltage source to the input interface of the inductive voltage divider via a coaxial wire, uses a high-precision meter to test the proportional output voltage at the output interface, adjusts the fine-tuning knob to achieve the most accurate output value, and after calibration, connects the source to be measured for use. A single high-ratio binary inductive voltage divider can achieve ratios of: 1 / 2, 1 / 4, 1 / 8, 1 / 16, 1 / 32, 1 / 64, 1 / 128, and 1 / 256. When performing higher ratio voltage division, use the cascade structure of the input and output interface to cascade two inductive voltage dividers one after the other. Calibrate them before use. The product of the two voltage divider ratios is the overall output ratio, and the range is: 1 / 4, 1 / 8, 1 / 16, 1 / 32, 1 / 64, 1 / 128, 1 / 256, 1 / 512, 1 / 1024, 1 / 2048, 1 / 4096, 1 / 8192, 1 / 16384, 1 / 32768, 1 / 65536.

[0060] The beneficial effects of the present invention are that, compared with the prior art, the cascade-supporting inductive voltage divider of the present invention can sequentially implement a circular excitation winding, a proportional winding, and a disc-shaped housing through a sleeve arrangement, and integrate the input and output interfaces within the housing, thereby precisely implementing the structure of the inductive voltage divider. The inductive voltage divider of the present invention has a simple, safe, and reliable structure, minimizes line access errors and cascade line resistance errors, fully prevents external electromagnetic radiation in high-voltage environments, and has high measurement accuracy, strong reliability, and a long service life.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. An inductive voltage divider supporting cascade connection, characterized in that: The inductive voltage divider includes an input interface, an output interface, an excitation winding, a proportional winding and a housing; wherein, The proportional winding is a hollow annular body, which accommodates the excitation winding in the shape of a solid annular body, and a through hole is opened on the outer side of the hollow annular body. The input interface is arranged on the through hole to connect the tap of the excitation winding with the inner and outer conductors of the input interface; The output interface is provided on the opposite side of the input interface, and the ends of both are fixedly connected to the housing to achieve internal sealing of the inductive voltage divider; The shell is in a circular shape and wrapped around the outside of the proportional winding. A fine-tuning knob and a gear selection button are provided on the shell, which are connected to the tap of the proportional winding in turn, and the tap of the proportional winding is indirectly connected to the inner and outer conductors of the output interface.

2. The cascade-capable inductive voltage divider according to claim 1, characterized in that: The input interface and the output interface are both cylindrical, and the ends of the cylinders are fixedly connected to the outer side of the circular ring of the shell; The physical axes of the input interface and the output interface coincide with each other, pass through the geometric center of the shell, and are perpendicular to the axis of the shell.

3. The cascade-capable inductive voltage divider according to claim 1, characterized in that: The excitation winding and the proportional winding each include an iron core and a winding conductor wound on the iron core; Wherein, the iron core is a silicon steel sheet, and the winding conductor is a copper cable; The interior of the iron core of the proportional winding is coated with insulating varnish.

4. The cascade-capable inductive voltage divider according to claim 3, characterized in that: The first end tap and the end tap of the winding wire in the excitation winding are respectively connected to the inner conductor and the outer conductor of the input interface; An insulating sheath is provided on the cylindrical surface of the input interface so that the input interface passes through the housing and the proportional winding and is connected to the tap of the excitation winding in an externally insulated manner.

5. The cascade-capable inductive voltage divider according to claim 2, wherein: The proportional winding realizes the gear division of the winding wire based on the binary proportional method; All taps on the winding wires allocated to the current gear are led out from the proportional winding and are uniformly welded on the fine-tuning knob.

6. The cascade-capable inductive voltage divider according to claim 5, characterized in that: The fine-tuning knob includes an arc-shaped fixed piece and a pointer-shaped movable piece; One end of the pointer-shaped movable piece is fixed to the center of the arc-shaped stator, and is rotated by a screw of a fine-tuning knob also provided at the center of the circle so that the other end of the pointer-shaped movable piece contacts different positions of the arc-shaped stator; Furthermore, the stud of the fine-tuning knob and one end of the arc-shaped stator are connected to the gear selection button via a wire; The head end of the arc-shaped stator is connected to the outer conductor of the output interface through a first wire.

7. The cascade-capable inductive voltage divider according to claim 6, characterized in that: The other end of one end of the gear selection button is connected to the inner conductor of the output interface through a second wire; The gear selection button is a circuit switch.

8. The cascade-capable inductive voltage divider according to claim 7, characterized in that: The inductive voltage divider includes a plurality of fine-tuning knobs and a plurality of gear selection buttons of equal number; and, A plurality of first conducting wires are connected in parallel and then connected to the outer conductor of the output interface, and a plurality of second conducting wires are connected in parallel and then connected to the inner conductor of the output interface.

9. The cascade-capable inductive voltage divider according to claim 8, characterized in that: The input interface and the output interface are sequentially provided with an inner conductor, an insulating gasket, an outer conductor and an insulating sheath of a coaxial interface from the inside to the outside.

10. The cascade-capable inductive voltage divider according to claim 9, characterized in that: The exterior of the insulating sheath is a smooth structure or a threaded structure; The inductive voltage divider further comprises an internal threaded pipe fitting, wherein the internal thread of the internal threaded pipe fitting is coupled with the thread structure of the insulating sheath to achieve cascading of a plurality of the inductive voltage dividers; The smooth structure of the insulating sheath is coupled with the wiring terminal of the coaxial cable to achieve the connection between the inductive voltage divider and the AC voltage dividing circuit.

11. The cascade-capable inductive voltage divider according to claim 10, characterized in that: A plurality of fine-tuning knobs and gear selection buttons are arranged in parallel and at equal intervals on the outer wall of the top surface of the housing; The shell is made of brass material, and the inner surface is sprayed with insulating paint. The position where the input interface and the output interface are fixedly connected is a threaded hole coupled with the threaded interface of the insulating sheath.

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