Power supply wall box with strong electromagnetic pulse combined protection and high shielding effectiveness

Abstract

The invention relates to a power supply wall box with strong electromagnetic pulse combined protection and high shielding effectiveness, which belongs to the technical field of electronic equipment shielding square cabins and comprises a shell, an out-cabin panel, an in-cabin panel, a power supply lightning protection device and a combined filter. An out-cabin panel is installed at one end of the shell, an in-cabin panel is installed at the other end of the shell, and the shell is fixed to a cabin plate of the square cabin. And a plurality of connector sockets are arranged on the panels outside and inside the cabin in a one-to-one correspondence manner to form a plurality of groups of power interfaces. The plurality of combined filters are mounted on a mounting plate in the shell, the combined filters are connected in series in a power supply loop of a group of connector sockets, and the power supply lightning protection devices are mounted on an out-cabin panel and are connected into the power supply loop of the corresponding group of connector sockets. Through the integrated design of lightning protection, HEMP protection and EMI filtering of the square cabin power supply, and in cooperation with the structural design of the wall box, the problems that an existing square cabin wall box is single in protection function and does not have the lightning protection function, the HEMP protection function and the high shielding effect at the same time are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic equipment shielding cabins, and specifically relates to a power wall box with strong electromagnetic pulse combined protection and high shielding efficiency, wherein the strong electromagnetic pulse combined protection includes lightning (LEMP) protection and high-altitude nuclear electromagnetic pulse (HEMP) protection. Background Art

[0002] Electronic equipment shielding shelters are widely used mobile military facilities, offering advantages such as rapid mobility and high shielding effectiveness. During operation, electronic shelters must withstand a variety of complex strong electromagnetic pulse environments, including lightning strikes (LEMP), high-altitude nuclear electromagnetic pulses (HEMP), and high-power microwaves (narrowband HPM-NS and ultra-wideband HPM-UWB). Lightning is a natural electromagnetic phenomenon, while the others are man-made. Strong electromagnetic pulses can couple very high energy into the shelter through antennas, cables, holes, and gaps. These pulses, with their high voltage, high current, and wide bandwidth, can cause severe interference to the equipment and components within the shelter, rendering the system inoperable or even causing permanent damage to components. Therefore, they must be suppressed.

[0003] A typical high-altitude nuclear electromagnetic pulse (HEMP) has a rising edge time of approximately 10 nanoseconds and a pulse width of 500 nanoseconds. Its peak field strength can reach 50 kV / m, with a range of several thousand kilometers. Its frequency range can range from very low frequencies to hundreds of megahertz, and its energy is concentrated within the common radio frequency range, posing a serious threat to electronic and electrical equipment. When operating in the field, shielded shelters are highly susceptible to lightning damage (usually induced lightning) in the event of thunderstorms. Lightning is extremely powerful, making the consequences of damage even more severe.

[0004] The power supply circuit cables for the shielded cabin are long and have low internal resistance, making them very susceptible to coupling with strong electromagnetic pulses. The coupled energy is extremely large, causing damage to the electrical equipment in the cabin and causing serious electromagnetic interference (EMI).

[0005] Therefore, it is worth studying how to ensure that the shielded cabin can work normally in a complex electromagnetic pulse environment and ensure the normal use of the cabin's power supply.

[0006] Currently, lightning shielding, HEMP shielding, and EMI filtering for shelter power circuits are performed independently, each fulfilling its own purpose. For example, existing lightning protection enclosures for power supplies, equipped with lightning arresters, only protect against lightning pulses. They offer no effective and reliable protection against high-altitude nuclear electromagnetic pulses (HEMPs) and lack EMI filtering capabilities.

[0007] Therefore, it is necessary to carry out systematic integration design of power supply lightning arresters, cabin power supply filters and high-altitude nuclear explosion electromagnetic pulse protection circuits to meet multiple protection needs. Summary of the Invention

[0008] Technical issues to be solved:

[0009] In order to avoid the shortcomings of the existing technology, the present invention provides a power wall box with strong electromagnetic pulse combined protection and high shielding efficiency, and integrates the lightning protection, HEMP protection and EMI filtering of the cabin power supply into a design. Combined with the wall box structure design, it solves the problem that the existing cabin wall box has a single protection function and does not have lightning protection, HEMP protection and high shielding efficiency at the same time.

[0010] The technical solution of the present invention is: a power supply wall box with strong electromagnetic pulse combined protection and high shielding effectiveness, comprising a shell, an outer panel, an inner panel, a power supply lightning arrester and a combined filter;

[0011] The shell is closed around its periphery and open at both ends. The inner cavity of the shell is provided with mounting plates to block the two openings. An outer panel is mounted at one open end of the shell to close the end opening, and an inner panel is mounted at the other open end to close the end opening. One end of the shell located at the inner panel is fixed to the cabin board of the square cabin.

[0012] The outer panel and the inner panel are provided with a plurality of connector sockets in a one-to-one correspondence, and a corresponding group of connector sockets forms a group of power interfaces; a plurality of combination filters are installed on the mounting plate in the shell, and each group of power interfaces corresponds to a corresponding combination filter and power supply lightning arrester. The combination filter is connected in series in the power circuit of a group of connector sockets to provide HEMP protection and EMI filtering for the corresponding group of power interfaces;

[0013] The power supply lightning arrester is installed on the outer panel of the cabin. The input end of the power supply lightning arrester is connected to the power supply circuit of the corresponding group of connector sockets and is located at the front end of the combined filter in the power supply circuit. The output end of the power supply lightning arrester is grounded.

[0014] A further technical solution of the present invention is: a mounting flange is provided around the end of the shell close to the interior panel, and the mounting flange is provided with double rows of mounting holes that are staggered and evenly distributed, which are used to be fixedly connected to the outer wall of the cabin panel by screws; mounting surfaces are provided at the open ends of the shell, which are used to respectively install the exterior panel and the interior panel by screws.

[0015] A further technical solution of the present invention is: low-impedance conductive shielding material is padded between the outer panel and the outer mounting surface of the shell, and between the inner panel and the inner mounting surface of the shell for electromagnetic isolation; the mounting plate electromagnetically isolates the two sides of the shell cavity; the outer panel, the inner panel and the mounting plate together form three layers of shielding isolation for the power wall box.

[0016] A further technical solution of the present invention is: the combined filter is a through-wall lead filter, including a filter housing and an internal circuit installed in the filter housing; the filter housing is installed on a mounting plate in the wall box housing through a hollow screw, and the fitting surface between the filter housing and the mounting plate is covered with conductive material for low-impedance grounding of the filter housing.

[0017] A further technical solution of the present invention is: the internal circuit of the combined filter includes a front-stage HEMP protection circuit and a rear-stage EMI filter circuit, the EMI filter circuit is connected in series in the main power supply circuit, the input end of the HEMP protection circuit is connected to the main power supply circuit at the front end of the EMI filter circuit, and the output end of the HEMP protection circuit is grounded.

[0018] A further technical solution of the present invention is as follows: the filter housing includes a housing body, a front cover plate, and a rear cover plate; the housing body is a hollow structure with one side open, and the interior is divided into a front compartment and a rear compartment by a partition plate; the front compartment is sealed by the front cover plate, and the rear compartment is sealed by the rear cover plate; the input end cable of the combination filter is connected to its internal circuit through one end of the front compartment, the HEMP protection circuit is installed in the front compartment, and a through-hole capacitor is installed on the partition plate for electromagnetic isolation between the input and output of the combination filter; the hollow screw is located on the filter housing mounting surface at the rear compartment, and is used to pass through the output end cable of the combination filter and install the filter housing;

[0019] The input cable of the combined filter is connected in parallel to the power lightning arrester and is electrically connected to the connector socket of the panel outside the cabin; the output cable is electrically connected to the connector socket of the panel inside the cabin.

[0020] A further technical solution of the present invention is: a waveguide is installed in the hollow screw, and the output end of the combined filter is connected to the output end cable of the combined filter through the waveguide.

[0021] A further technical solution of the present invention is that the filter housing is made of steel plate and processed by sheet metal, and the surface is nickel-plated.

[0022] A further technical solution of the present invention is that the transient protection device in the HEMP protection circuit adopts a varistor and a ceramic gas discharge tube connected in series.

[0023] A further technical solution of the present invention is that the shell of the wall box is formed by sheet metal bending, and each joint of the shell is formed by a continuous welding process.

[0024] Beneficial effects

[0025] The beneficial effects of the present invention are as follows: the present invention provides a power supply wall box with strong electromagnetic pulse combined protection and high shielding effectiveness. According to the electrical characteristics of each group of interface circuits in the shielded cabin power transfer window, the corresponding lightning arrester and combined filter are selected. The wall box is matched with the wall box housing and filter housing with high electromagnetic isolation to produce an integrated wall box. The wall box is assembled in the shielded cabin power transfer window. The wall box has multiple functions such as lightning (LEMP) protection, high-altitude nuclear electromagnetic pulse (HEMP) protection, and EMI filtering, thereby realizing the transmission of electric energy inside and outside the cabin. At the same time, the wall box is compact, lightweight, and has good maintainability and environmental adaptability. The present invention organically integrates the protection of lightning (LEMP), high-altitude nuclear electromagnetic pulse (HEMP), and EMI based on their different distribution frequency bands, energy levels, and protective measures.

[0026] Compared with the existing shelter power wall box, the present invention has the following advantages:

[0027] 1. Multiple functional combinations. In the power supply circuit in the wall box of the present invention, the front part is lightning protection, which adopts a power supply lightning arrester, which is mature and reliable and has a failure prompt function. The rear part is a combined filter, the front stage of which is a HEMP protection circuit and the rear stage is an EMI filtering circuit. By combining the filtering circuit with the HEMP protection circuit, the protection startup is timely and reliable, and the protection voltage is lower. The power supply circuit realizes the combination of electromagnetic pulse protection and steady-state filtering, and has multiple functions of lightning protection, HEMP protection and EMI filtering.

[0028] 2. Integrated filtering and shielding design. The power wall box housing in this invention is formed using sheet metal bending and continuous welding processes, achieving high electromagnetic isolation between the interior and exterior of the cabin. The combined filter utilizes a shielded structure with isolated input and output, filtering all power cables. The combined filter is individually modularized and integrated with the wall box housing's shielding structure to meet the high shielding efficiency requirements of the cabin.

[0029] 3. Modular design. This invention pairs a power wall box with each power transfer window in the shelter. Based on the characteristics of the power circuit corresponding to a set of connector sockets at both ends of the wall box, a corresponding filter is designed and installed. That is, one set of connector sockets corresponds to one combined filter. This provides clear functional division, facilitates installation, and greatly improves the maintainability of the equipment.

[0030] 4. Good environmental adaptability. The wall box shell (including its internal mounting plate), the outer panel and the inner panel of the present invention are all made of stainless steel with good processing performance and strong environmental adaptability. The wall box shell is made by continuous welding. The shell of the combined filter in the wall box is made of steel sheet metal processing and nickel-plated on the surface, which has excellent shielding and grounding comprehensive performance. This ensures that the wall box has good environmental adaptability and can meet the normal operation of the container vehicle in various environments (such as heat and humidity, shock, vibration, mold, salt spray, etc.) BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the electrical schematic diagram of the lightning arrester and combined filter in the power supply circuit;

[0032] Figure 2 This is a schematic diagram of the assembly of the lightning arrester and combined filter in the power wall box;

[0033] Figure 3 Schematic diagram of the filter housing structure of the combined filter;

[0034] Figure 4 This is the first structural diagram of the power wall box, showing its outer panel side;

[0035] Figure 5 This is the first structural diagram of the power wall box, showing the panel side inside the cabin;

[0036] Figure 6 This is the second structural diagram of the power wall box, showing the outer panel side of the cabin;

[0037] Figure 7 This is the second external structural diagram of the power wall box, showing the panel side inside the cabin.

[0038] Explanation of the accompanying drawings: 1. Shell, 11. Mounting plate, 12. Mounting flange, 2. External panel, 3. Internal panel, 4. Power supply lightning arrester, 5. Combined filter, 51. Filter shell, 511. Shell body, 512. Front cover, 513. Rear cover, 514. Partition, 511. Hollow screw, 52. HEMP protection circuit, 53. EMI filtering circuit, 54. Input cable, 55. Input cable, 56. Through-hole capacitor, 57. Hollow screw, 6. Cabin, 7. Connector socket, 8. Power supply wall box. DETAILED DESCRIPTION

[0039] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0041] See Figure 2 This embodiment provides a power wall box with combined strong electromagnetic pulse protection and high shielding effectiveness. Installed in the shielded cabin power transfer window, it provides reliable protection for the power circuit of the electronic equipment shielded cabin in a strong electromagnetic pulse environment, enabling power transmission inside and outside the cabin while meeting the cabin's requirements for wide bandwidth and high shielding effectiveness. It also provides multiple functions for the cabin's power interface, including lightning (LEMP) protection, high-altitude nuclear electromagnetic pulse (HEMP) protection, and EMI filtering.

[0042] The present invention provides a power supply wall box with strong electromagnetic pulse combined protection and high shielding efficiency, comprising a shell 1, an outer panel 2, an inner panel 3, a power supply lightning arrester 4 and a combined filter 5.

[0043] The shell 1 is closed around its periphery and open at both ends. One end is open toward the cabin panel 6, and an interior panel 3 is installed on the open end facing the panel 6 to close the end opening. The other end of the shell 1 is open away from the cabin panel 6, and an exterior panel 2 is installed on the open end facing away from the panel 6 to close the end opening. Panel mounting surfaces are provided at both end openings of the shell 1 for mounting the exterior panel 2 and interior panel 3 respectively by screws. A mounting flange 12 is provided around the end of the shell 1 facing the cabin panel 6, and the mounting flange 12 is provided with double rows of mounting holes that are staggered and evenly distributed for fixing to the outer wall of the cabin panel 6 by screws. Correspondingly, a wall box mounting window that passes through the inside and outside of the cabin is provided on the panel 6. A mounting plate 11 is provided in the inner cavity of the shell 1 to block the openings at both ends, thereby dividing the inner cavity of the shell 1 into two chambers.

[0044] The housing 1 is formed from stainless steel sheet metal, with all seams continuously welded. Low-impedance conductive shielding material is placed between the exterior panel 2 and the exterior mounting surface of the housing 1, and between the interior panel 3 and the interior mounting surface of the housing 1. These panels form two layers of electromagnetic isolation between the exterior and interior of the power wall box. The mounting plate 11 electromagnetically isolates the mounting plate on both sides of the housing 1. This forms the main isolation interface of the power wall box, and together with the exterior and interior panels 2 and 3, provides a three-layer isolation shield.

[0045] The double-row mounting holes on the mounting flange 12 of the housing 1 have extremely close spacing between the screws and holes. The mounting surface between the outer wall of the cabin panel 6 and the mounting flange 12 is padded with low-impedance conductive shielding material. The screw connection between the housing 1 and the cabin panel 6 not only securely attaches the power wall box to the outer wall of the cabin panel 6 but also achieves high electromagnetic isolation inside and outside the cabin, fully meeting the cabin's requirements for broadband and high-efficiency shielding.

[0046] See Figure 1 、 2Multiple connector sockets 7 are provided on the exterior panel 2 and interior panel 3, correspondingly with each other. A corresponding group of connector sockets 7 forms a set of power interfaces. The connector sockets 7 are used to quickly connect and disconnect cable connectors inside and outside the cabin, enabling power connection. Multiple combination filters 5 are mounted on a mounting plate 11 within the housing 1. Each group of power interfaces corresponds to a corresponding combination filter 5 and a corresponding power surge arrester 4. The combination filters 5 are connected in series to the power circuit of a group of connector sockets 7, providing HEMP protection and EMI filtering for the corresponding group of power interfaces.

[0047] The power surge arrester 4 is mounted on the exterior panel 2. Its input is connected to the power circuit of the corresponding set of connector sockets 7 and is located in front of the combined filter 5 within this power circuit. Its output is grounded. The power surge arrester 4 in this invention is a certified, reliable product with a failure notification function. Each lightning protection module 41 within it can be quickly replaced, providing excellent maintainability and reliability.

[0048] The combined filter 5 is a through-the-wall lead-through filter, comprising a filter housing 51 and internal circuitry mounted within the filter housing 51. The filter housing 51 is mounted to the mounting plate 11 within the wall box housing 1 using a hollow screw 57 provided with the combined filter 5. The mating surfaces of the filter housing 51 and the mounting plate 11 are coated with a conductive material, providing low-impedance grounding for the filter housing 51 and, consequently, for the internal HEMP protection circuit 52.

[0049] See Figure 2 、 3The filter housing 51 includes a housing 511, a partition 514, a front cover 512, and a rear cover 513. The housing 511 is a hollow structure with one side open, and its interior is divided into a front compartment and a rear compartment by a partition 514. The front compartment is sealed by the front cover 512, and the rear compartment is sealed by the rear cover 513. The input cable 54 of the combined filter 5 is connected to its internal circuit from one end of the front compartment. The internal circuit of the combined filter 5 includes a front-stage HEMP protection circuit 52 and a rear-stage EMI filter circuit 53. The EMI filter circuit 53 is connected in series to the main power supply circuit. The input end of the HEMP protection circuit 52 is connected to the main power supply circuit at the front end of the EMI filter circuit 53, and the output end of the HEMP protection circuit 52 is grounded. The HEMP protection circuit 52 is installed in the front compartment, and a feedthrough capacitor 56 is installed on the partition 514 to provide electromagnetic isolation between the input and output of the combined filter 5. The front compartment is equipped with inductors and capacitors with different frequency characteristics, which together with the feedthrough capacitor 56 form a steady-state EMI filter circuit. The EMI filter circuit not only has excellent broadband filtering performance, but also delays the HEMP pulse current coupled to the cable, which can promote a more reliable response and startup of the HEMP protection module. The hollow screw 57 is located on the mounting surface of the filter housing at the rear cabin, and a waveguide is installed inside. The output end of the combined filter 51 is connected to the output end cable 55 of the combined filter through the waveguide. The input end cable 54 of the combined filter is connected in parallel with the power supply lightning arrester 4 and is electrically connected to the connector socket 7 of the external panel 2; its output end cable 55 is electrically connected to the connector socket 7 of the internal panel 3.

[0050] The combined filter 5 is an independent shielding structure to ensure high shielding efficiency of the wall box as a whole. The combined filter housing 51 is made of low-carbon steel sheet metal and nickel-plated on the surface, which has excellent shielding and grounding performance. The through-hole capacitor 56 assembled on the front and rear cabin isolation plates realizes high electromagnetic isolation between the filter input and output. The combined filter is installed on the mounting plate 11, which serves as the main isolation interface of the wall box. The output enters the cabin through the waveguide, ensuring high electromagnetic isolation between the input and output. The mounting surface of the combined filter 5 in contact with the mounting plate 11 in the wall box is covered with conductive material and grounded with low impedance to ensure that the topological flow of the filter current is on the outer surface of the cabin wall.

[0051] In order to ensure the smooth flow of the discharge circuit, the power supply wall box housing 1 must be connected to the cabin plate 6 with low impedance conductive connection; the combined filter 5 must be connected to the power supply wall box housing 1 with low impedance conductive connection.

[0052] The internal circuit of the combined filter 5 includes two parts: a HEMP protection circuit and an EMI filter circuit. When there is no strong electromagnetic pulse, the HEMP protection circuit is in an open circuit state; the EMI filter circuit is connected in series in the loop, providing excellent filtering performance and meeting the electromagnetic compatibility conduction and radiation (such as shielding effect) characteristics requirements of the cabin.

[0053] When a strong electromagnetic pulse (EMP) strikes, the HEMP protection circuit responds by bypassing the pulse current to the ground, thereby protecting downstream equipment and components. Within the HEMP distribution frequency band, the impedance characteristics of the EMI filter module match those of the HEMP protection module, making the HEMP protection circuit's response more timely and reliable, ensuring effective protection.

[0054] Because existing transient protection devices are primarily developed and manufactured for lightning pulses, the nonlinearity of their inherent parameters can significantly change under nanosecond-level pulses, rendering the original parameters no longer applicable. To address the requirements for HEMP electromagnetic pulse protection, and to overcome the limitations of single transient protection devices, such as susceptibility to aging and power-frequency freewheeling, multiple transient protection devices are combined to overcome inherent limitations and effectively protect downstream circuits. Based on the characteristics of commonly used transient protection devices, this embodiment utilizes a series connection of a varistor and a ceramic gas discharge tube in the HEMP protection circuit to achieve the HEMP protection circuit design.

[0055] When selecting a transient protection device, first determine its startup voltage. To ensure proper operation, it's generally 1.8 to 2 times the rated circuit voltage. According to the pulse current injection (PCI) test requirements of GJB18848, the maximum line-to-ground peak current for the power line is 2500A. Since the width of the HEMP pulse current (500ns) is significantly smaller than the width of the lightning pulse current (20μs), the transient protection device's current flow rate should be greater than 2500A. Once these two indicators are determined, the parameters of the varistor and ceramic gas discharge tube can be determined.

[0056] The present invention is designed with a corresponding derating factor based on the power capacity of the power supply circuit. In particular, a lower derating factor is used for high-current circuits, ensuring the safe and reliable operation of the power supply circuit and ensuring that the cabin can meet high shielding efficiency requirements under actual working conditions (especially high temperature conditions).

[0057] See Figure 4-7 , Figure 4 、 5 This is the first external structure of the power wall box of the present invention. Figure 6 、 7 This is the second external structure of the power wall box of the present invention, the difference is Figure 4 、 5 The first type of power wall box shown has fewer power circuits and a smaller overall structure; Figure 6 、 7 The second type of power wall box shown in the second embodiment has many power circuits and a large overall size. The external dimensions and number of circuits of the power wall box are determined according to specific usage requirements.

[0058] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A power wall box with strong electromagnetic pulse combined protection and high shielding effectiveness, characterized in that: It includes a shell, an outer panel, an inner panel, a power supply lightning arrester and a combined filter; The shell is closed around its periphery and open at both ends. The inner cavity of the shell is provided with mounting plates to block the two openings. An outer panel is mounted at one open end of the shell to close the end opening, and an inner panel is mounted at the other open end to close the end opening. One end of the shell located at the inner panel is fixed to the cabin panel. The outer panel and the inner panel are provided with a plurality of connector sockets corresponding to each other, and a corresponding group of connector sockets forms a group of power interfaces; a plurality of combination filters are installed on the mounting plate in the shell, and each group of power interfaces corresponds to a corresponding combination filter and power supply lightning arrester. The combination filter is connected in series in the power circuit of a group of connector sockets to provide HEMP protection and EMI filtering for the corresponding group of power interfaces; The power supply lightning arrester is installed on the outer panel of the cabin. The input end of the power supply lightning arrester is connected to the power supply circuit of the corresponding group of connector sockets and is located at the front end of the combined filter in the power supply circuit. The output end of the power supply lightning arrester is grounded.

2. The power wall box with strong electromagnetic pulse combined protection and high shielding effectiveness according to claim 1, characterized in that: The shell is provided with a mounting flange around the end close to the cabin panel, and the mounting flange is provided with double rows of mounting holes evenly distributed in an staggered manner, which is used to be fixedly connected to the outer wall of the cabin panel by screws; the open ends of the shell are provided with mounting surfaces for respectively installing the cabin outer panel and the cabin inner panel by screws.

3. The power wall box with strong electromagnetic pulse combined protection and high shielding effectiveness according to claim 2, characterized in that: Low-impedance conductive shielding materials are padded between the outer panel and the outer mounting surface of the shell, and between the inner panel and the inner mounting surface of the shell for electromagnetic isolation; the mounting plate electromagnetically isolates the two sides of the shell cavity; the outer panel, the inner panel and the mounting plate together form three layers of shielding isolation for the power wall box.

4. The power wall box with strong electromagnetic pulse combined protection and high shielding effectiveness according to claim 1, characterized in that: The combined filter is a through-wall lead-type filter, comprising a filter housing and an internal circuit installed in the filter housing; the filter housing is installed on a mounting plate in the wall box housing through a hollow screw, and the mating surface between the filter housing and the mounting plate is covered with conductive material for low-impedance grounding of the filter housing.

5. The power wall box with strong electromagnetic pulse combined protection and high shielding effectiveness according to claim 4, characterized in that: The internal circuit of the combined filter includes a front-stage HEMP protection circuit and a rear-stage EMI filter circuit. The EMI filter circuit is connected in series to the main power supply circuit. The input end of the HEMP protection circuit is connected to the main power supply circuit at the front end of the EMI filter circuit, and the output end of the HEMP protection circuit is grounded.

6. The power wall box with strong electromagnetic pulse combined protection and high shielding effectiveness according to claim 5, characterized in that: The filter housing includes a housing, a partition, a front cover, and a rear cover; the housing is a hollow structure with one side open, and the interior is divided into a front compartment and a rear compartment by a partition; the front compartment is sealed by the front cover, and the rear compartment is sealed by the rear cover; the input end cable of the combined filter 5 is connected to its internal circuit from one end of the front compartment, the HEMP protection circuit is installed in the front compartment, and a through-hole capacitor is installed on the partition for electromagnetic isolation between the input and output of the combined filter; the hollow screw is located on the mounting surface of the filter housing at the rear compartment, and is used to pass through the output end cable of the combined filter and install the filter housing; The input cable of the combined filter is connected in parallel with the power surge protector and is electrically connected to the connector socket on the outer panel; The output end cable is electrically connected to the connector socket of the cabin panel.

7. The power wall box with strong electromagnetic pulse combined protection and high shielding effectiveness according to claim 6, characterized in that: A waveguide is installed in the hollow screw, and the output end of the combined filter is connected to the output end cable of the combined filter through the waveguide.

8. The power wall box with strong electromagnetic pulse combined protection and high shielding effectiveness according to claim 6, characterized in that: The filter housing is made of steel plate and processed by sheet metal, and the surface is nickel-plated.

9. The power wall box with strong electromagnetic pulse combined protection and high shielding effectiveness according to claim 5, characterized in that: The transient protection device in the HEMP protection circuit adopts a varistor and a ceramic gas discharge tube connected in series.

10. The power wall box with strong electromagnetic pulse combined protection and high shielding effectiveness according to claim 1, characterized in that: The shell of the wall box is formed by sheet metal bending, and each joint of the shell is formed by continuous welding.

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