Electrical component test bench and circuit system thereof

Abstract

This utility model discloses an electrical component repair bench and its circuit system, including a repair bench body, an operation panel, a rotating platform, an electrical card holder, a solder wire reel, a soldering iron holder, a voltmeter, an adjustable voltage LCD display, and an internal circuit system. The internal circuit system includes an AC power input unit, a first voltage conversion branch, a second voltage conversion branch, and a DC power conversion branch. AC power and DC power are output through the first repair socket group X3-X8 and the second repair socket group X9-X10, respectively, to realize independent power supply control for one or more electrical components to be repaired, thereby improving the flexibility of powering multiple components simultaneously or separately during repair operations.

Description

Technical Field

[0001] This utility model relates to the technical field of electrical component repair devices, specifically to an electrical component repair bench and its circuit system. Background Technology

[0002] With the continuous increase in the amount of electrical equipment deployed underground in mining areas, the number of electrical devices requiring maintenance and repair after being brought to the surface is also rising. During actual maintenance, damage and malfunctions of electrical components occur frequently, including a large number of expensive components with unit prices ranging from hundreds to thousands of yuan (such as vacuum circuit breakers, vacuum AC contactors, and relays). If these components are discarded directly due to a lack of suitable maintenance and testing conditions, the material costs for routine switch maintenance will increase significantly, resulting in resource waste. Therefore, it is urgent to achieve component reuse through effective maintenance methods to reduce costs and ensure the performance of explosion-proof switches.

[0003] Currently, there are two major problems in the maintenance and training related to the aforementioned electrical components:

[0004] Firstly, the safety risks are significant. In traditional maintenance procedures, if a switch malfunctions, it must be disassembled from the equipment and then powered on with a 660V high-voltage power supply for testing to locate the cause of the fault. A maintenance worker needs to perform this high-voltage test dozens of times per month. Even with protective measures, frequent contact with 660V high voltage can easily lead to electric shock accidents, posing a serious threat to the personal safety of operators. Although some existing electrical component maintenance benches use a 220V AC input power supply and output DC 48V, 36V, and 24V voltages through AC / DC converters, or output adjustable AC voltages from 0-220V through voltage regulators, and are equipped with 220V to 36V transformers to power the on / off indicator lights, operating at voltages higher than 36V still poses potential safety hazards and fails to fundamentally solve the risk problem of high-voltage operation.

[0005] Secondly, the training was ineffective. In the practical training sessions for electrical maintenance personnel, many of the electrical components to be explained were hidden inside switches or equipment, making their structure, working principles, and operational processes after being energized difficult to observe directly. Trainers had to spend a significant amount of time explaining the internal structure of these components, yet they couldn't demonstrate crucial details such as the on / off positions of contacts, contact shapes and colors, and oxidation states, leading to ambiguous understanding among trainees. Furthermore, due to a lack of safe hands-on training conditions, trainees struggled to operate and test the components themselves, resulting in low skill acquisition efficiency and failing to meet the technical requirements of on-site maintenance personnel.

[0006] Furthermore, while existing maintenance benches can perform inspections on some components, their structural design does not adequately consider ergonomics and ease of operation, and they are not optimized for training scenarios, making it difficult to simultaneously improve maintenance efficiency, operational safety, and training effectiveness. In conclusion, the field of electrical component maintenance in mining areas urgently needs a technical solution that can mitigate high-voltage risks, reduce material costs, and simultaneously enhance the intuitiveness and safety of training to address the shortcomings of existing technologies. Summary of the Invention

[0007] To address the technical problems of existing electrical component repair equipment in practical applications, such as limited voltage compatibility, insufficient safety protection, low operating efficiency, and unreasonable structural design, this utility model provides an electrical component repair bench that achieves safe, efficient, and compatible integrated repair operations.

[0008] The technical solution adopted in this utility model is: an electrical component repair bench, comprising:

[0009] The main body of the maintenance platform provides a supporting carrier for the entire maintenance platform. An emergency stop normally closed switch S1 is installed on the platform surface, and the side integrates the adjustment knob of the adjustable AC transformer T2, the thermal overload protection normally closed switch S3 and the thermal overload protection normally closed switch S4.

[0010] The operation panel is located on the upper part of the main body of the maintenance platform and integrates circuit breaker Q1, fuse F2, fuse F3 and display components.

[0011] A rotating platform is installed on the table surface of the main body of the inspection platform, used to place electrical components to be inspected and can be rotated to adjust the angle;

[0012] An electrical component holder is located on the edge of the rotating platform and is used to secure and fix the electrical components to be inspected.

[0013] A solder wire reel is set on the table surface of the main body of the inspection bench for winding and placing solder wire.

[0014] A soldering iron holder is provided on the table surface of the main body of the inspection bench for placing soldering irons.

[0015] A voltmeter, embedded in the operation panel, is used to display the voltage value output by the maintenance bench;

[0016] An adjustable voltage LCD display is embedded in the operation panel to display the output voltage parameters of the adjustable AC transformer T2;

[0017] The internal circuit system includes an AC power input unit, a main power protection unit, a first voltage conversion branch, a second voltage conversion branch, and a DC power conversion branch. All of the above components are electrically connected inside the main body of the maintenance platform through wires and output through the X3-X10 sockets on the surface of the main body of the maintenance platform.

[0018] Furthermore, the surface of the main body of the inspection platform is made of anti-static insulating material.

[0019] Furthermore, the rotating platform is an electric rotating platform, equipped with a stepper motor and an angle positioning mechanism, which can rotate and position steplessly within the range of 0-360°, and the platform surface is made of anti-static insulating material.

[0020] Furthermore, the bottom of the main body of the maintenance platform is provided with several steering wheels for moving the main body of the maintenance platform.

[0021] This utility model also provides a circuit system for an electrical component repair bench, including:

[0022] The AC power input unit has a neutral terminal X1 and a live terminal X2 for connecting to an AC / DC converter.

[0023] The main power protection unit includes a circuit breaker Q1 and a fuse F1 connected in series between the live wire terminal X2 and the subsequent circuit. The circuit breaker Q1 is used for manually disconnecting the main power supply of the main circuit, and the fuse F1 is used for short circuit protection of the main circuit.

[0024] The first voltage conversion branch includes a step-down transformer T1, a fuse F2, an emergency stop normally closed switch S1, a start normally open switch S2, relays K1 and K2 (three sets of contacts), and a first maintenance socket group X3-X8. The primary side of the step-down transformer T1 is connected to the AC power input unit, and the secondary side outputs low-voltage AC power. The fuse F2 is connected in series between the secondary output terminal of the step-down transformer T1 and the emergency stop normally closed switch S1. The coils of the emergency stop normally closed switch S1, the start normally open switch S2, and the relay K1 are connected in series to the secondary circuit of the step-down transformer T1, and one set of contacts of the relay K1 is connected in parallel with the start normally open switch S2 to form a self-locking circuit. The three sets of contacts of the relay K2 are connected in parallel in the secondary circuit of the step-down transformer T1, with both ends of each set of contacts connected to one end of the first maintenance socket group X3-X8. The other end of the first maintenance socket group X3-X8 is connected to the secondary circuit of the step-down transformer T1.

[0025] The second voltage conversion branch includes an adjustable AC transformer T2, a normally closed thermal overload protection switch S3, a fuse F3, another set of contacts of relay K1, and relay K2; wherein, the input terminal of the adjustable AC transformer T2 is connected to the AC power input unit, and the output terminal is connected to the output circuit of the adjustable AC transformer T2 via the fuse F3, the other set of contacts of relay K1, and the coil of relay K2 in series; the normally closed thermal overload protection switch S3 is connected in series between the input terminal of the adjustable AC transformer T2 and the fuse F1 of the main power protection unit;

[0026] The DC power conversion branch includes an AC / DC converter, a normally closed thermal overload protection switch S4, and a second maintenance socket group X9-X10; wherein, the AC input terminal of the AC / DC converter is connected to the AC power input unit, and the DC output terminal outputs an adjustable voltage; the normally closed thermal overload protection switch S4 is connected in series between the AC input terminal of the AC / DC converter and the fuse F1 of the main power protection unit; the DC positive output terminal of the AC / DC converter is directly connected to the positive socket X9 of the second maintenance socket group; the DC negative output terminal of the AC / DC converter is directly connected to the negative socket X10 of the second maintenance socket group.

[0027] Furthermore, the first maintenance socket group X3-X8 and the second maintenance socket group X9-X10 are circular maintenance sockets, which are adapted to standard maintenance plugs to connect electrical components to be maintained.

[0028] The beneficial effects of this utility model are:

[0029] 1. This utility model integrates three voltage output branches: AC36V safe low voltage, AC0-220V adjustable AC, and DC0-48V adjustable DC. This covers the maintenance needs of most small to medium-sized electrical components, allowing for the testing and repair of components of different specifications without the need for external power supplies. This solves the problems of traditional maintenance benches' single voltage and poor adaptability. Furthermore, real-time monitoring via a voltmeter and adjustable voltage LCD display enables precise voltage output control, reducing the risk of component damage due to voltage mismatch.

[0030] 2. This utility model constructs a three-level safety system of "main power protection - branch protection - emergency control": the main power supply end achieves dual overload and short-circuit protection through circuit breaker Q1 and fuse F1; each branch is equipped with thermal overload switches S3 and S4 and branch fuses F2 and F3, providing precise protection for different voltage types; the emergency stop switch S1 can quickly disconnect critical circuits to prevent the escalation of sudden accidents. In addition, the main body of the maintenance bench and the rotating platform surface are made of anti-static insulating material, effectively preventing static electricity from damaging sensitive electronic components and ensuring the safety of operators.

[0031] 3. The rotating platform adopts an electric drive and angle positioning design, which can be steplessly adjusted within the range of 0-360°. With the help of the electrical clamp, it can achieve multi-angle fixation and stable clamping of components to be repaired, solving the problems of cumbersome adjustment and easy loosening of components in traditional tabletops. At the same time, it integrates tool storage structures such as solder wire reel holder and soldering iron holder, reducing tool access time; the bottom steering wheel design improves the mobility of the equipment and adapts to the needs of different maintenance scenarios.

[0032] 4. This utility model facilitates on-site teaching and skills training for electrical maintenance personnel, allowing the structure and working principle of electrical components to be displayed to trainees more intuitively, which helps to improve the technical level of employees. Attached Figure Description

[0033] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0034] Figure 2 This is a schematic diagram of the circuit system of this utility model;

[0035] In the diagram: 1-Main body of the inspection bench, 2-Operation panel, 3-Rotating platform, 4-Electrical appliance slot, 5-Solder wire reel holder, 6-Soldering iron holder, 7-Voltmeter, 8-Adjustable voltage LCD display. Detailed Implementation

[0036] To more clearly illustrate the technical solution of this utility model, the accompanying drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort. To facilitate understanding of this utility model, a more detailed description of this utility model will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0037] like Figure 1 As shown, this utility model is an electrical component repair bench, including a repair bench body 1, an operation panel 2, a rotating platform 3, an electrical appliance holder 4, a solder wire coil holder 5, a soldering iron holder 6, and an internal circuit system. All parts work together to achieve convenient and safe repair of different electrical components.

[0038] The main body 1 of the maintenance platform provides support for the entire platform. It features a 1030×625×520mm cuboid frame made of 30mm angle iron, combined with an insulating panel. The platform surface is made of anti-static insulating material to effectively prevent damage to sensitive electrical components from static electricity. An emergency stop normally closed switch S1 is installed on the platform for quickly cutting off the maintenance power supply in emergencies. The sides integrate an adjustment knob for the adjustable AC transformer T2, a thermal overload protection normally closed switch S3, and a thermal overload protection normally closed switch S4. Furthermore, the main body 1 of the maintenance platform has several casters at its base for easy movement according to maintenance site requirements, improving its usability.

[0039] The control panel 2 is mounted on the upper part of the main body 1 of the maintenance platform. It is a right-angled trapezoidal frame with a length of 335mm, a top width of 120mm, a bottom width of 340mm, and a height of 305mm. All surfaces of the frame are made of insulating material. It integrates circuit breaker Q1, fuse F2, fuse F3, voltmeter 7, and adjustable voltage LCD display 8. The voltmeter 7 is either pointer or digital, with a measurement range of 0-500V, and displays the effective value of the maintenance platform's output voltage in real time. The adjustable voltage LCD display 8 can display the output value of AC 0-220V, improving the convenience and visibility of voltage adjustment. The rotating platform 3 is mounted on the tabletop of the main body 1 of the maintenance platform and is used to place the electrical components to be inspected.

[0040] In this embodiment, the rotating platform 3 is an electric rotating platform, which is equipped with a stepper motor and an angle positioning mechanism. It can rotate steplessly and accurately within the range of 0-360°, which is convenient for multi-angle maintenance. The table surface is made of anti-static insulating material, which is the same as the table surface material of the main body 1 of the maintenance platform, to ensure consistent electrostatic protection.

[0041] Electrical component holder 4 is located on the edge of the rotating platform 3 and is used to hold and fix the electrical components to be inspected.

[0042] Solder wire reel 5 and soldering iron holder 6 are set on the table surface of the main body 1 of the inspection table. Solder wire reel 5 is used to wind solder wire; soldering iron holder 6 is used to place soldering iron.

[0043] The internal circuit system of this utility model includes an AC power input unit, a main power protection unit, a first voltage conversion branch, a second voltage conversion branch, and a DC power conversion branch. Each component is electrically connected inside the main body 1 of the maintenance platform through wires, and the maintenance power is output through the maintenance socket group X3-X10 sockets on the platform.

[0044] like Figure 2 As shown, this is the internal circuit system of the present invention. The AC power input unit includes a neutral terminal X1 and a live terminal X2, which are used to connect to an external 220V AC power supply to provide initial power to the internal circuit system.

[0045] The main power protection unit includes a circuit breaker Q1 and a fuse F1 connected in series between the live wire terminal X2 and the subsequent circuit. The circuit breaker Q1 can manually disconnect the main power supply and also has overload and short-circuit protection functions. It automatically disconnects when the main circuit current is abnormal. The fuse F1 is a main circuit short-circuit protection device. When the main circuit is short-circuited, the fuse melts quickly, forcibly cutting off the main power supply.

[0046] The first voltage conversion branch outputs AC36V safe maintenance power, including a step-down transformer T1, fuse F2, emergency stop normally closed switch S1, start normally open switch S2, relays K1 and K2 (three sets of contacts), and the first maintenance socket group X3-X8. The primary side of the step-down transformer T1 is connected to the AC power input unit for AC220V input, and the secondary side outputs AC36V. Fuse F2 is connected in series between the secondary output terminal of the step-down transformer T1 and the emergency stop normally closed switch S1 for short-circuit protection of the AC36V branch. The emergency stop normally closed switch S1 is normally closed; pressing it in an emergency opens the contacts, directly cutting off the AC36V branch control circuit for rapid power disconnection. The start normally open switch S2 is connected in series with the emergency stop normally closed switch S1 and is normally open; pressing it connects the control circuit. The coil of relay K1 is connected in series with the start normally open switch S2 and then connected to the secondary circuit of the step-down transformer T1. One set of contacts of relay K1 is connected in parallel with the normally open start switch S2 to form a self-locking circuit. When the normally open start switch S2 is pressed, the coil of relay K1 is energized, and its contacts close. After the normally open start switch S2 is released, the coil of relay K1 remains energized through its closed contacts, ensuring continuous power supply after the AC36V branch is started. Three sets of relay K2 contacts are connected in parallel from the coil of relay K1 to the secondary circuit of step-down transformer T1. The two ends of each set of relay K2 contacts are connected to one end of the first maintenance socket group X3-X8, and the other end of the first maintenance socket group X3-X8 is connected to the secondary circuit of step-down transformer T1. When relay K1 is self-locking and relay K2 is closed, AC36V power is output through the first maintenance socket group X3-X8 to supply power to the AC36V components under maintenance.

[0047] The second voltage conversion branch outputs an adjustable AC 0-220V maintenance power supply, including an adjustable AC transformer T2, a normally closed thermal overload protection switch S3, a fuse F3, another set of contacts of relay K1, and relay K2. The input terminal of the adjustable AC transformer T2 is connected to the AC power input unit to input AC 220V. By rotating the adjustment knob on the side of the maintenance platform body 1, the position of the internal winding taps is changed, and the output terminal can continuously output an adjustable AC 0-220V voltage. The normally closed thermal overload protection switch S3 is a normally closed contact of a thermal relay, connected in series between the input terminal of the adjustable AC transformer T2 and the fuse F1 of the main power protection unit. When the AC 0-220V branch current is overloaded, the thermal element actuates to open the contacts, cutting off the power supply to the branch and realizing overload protection. The output terminal of the adjustable AC transformer T2 is connected to the output circuit of the adjustable AC transformer T2 via the fuse F3, the other set of contacts of relay K1, and the coil of relay K2 in series. Only when one set of contacts of relay K1 in the first voltage conversion branch is open, the other set of contacts of relay K1 in the second voltage conversion branch controls the output circuit of adjustable AC transformer T2 to be turned on. After the coil of relay K2 is energized, it supplies power to the AC0-220V maintenance output branch.

[0048] The DC power conversion branch outputs an adjustable DC 0-48V maintenance power supply, including an AC / DC converter, a normally closed thermal overload protection switch S4, and a second maintenance jack group X9-X10. The AC input terminal of the AC / DC converter connects to the AC power input unit for AC 220V input. It integrates rectification, filtering, and voltage regulation circuits internally, and outputs an adjustable DC voltage of 0-48V. The normally closed thermal overload protection switch S4 is a normally closed contact of a thermal relay, connected in series between the AC input terminal of the AC / DC converter and F1 of the main power protection unit. When the DC 0-48V branch current is overloaded, the thermal element activates, causing the contacts to open and cutting off the AC power supply to the AC / DC converter, thus achieving overload protection. The positive DC output terminal of the AC / DC converter connects to the positive jack X9, and the negative DC output terminal connects to the negative jack X10. When the normally closed thermal overload protection switch S4 is closed, the DC 0-48V power supply is output through X9 and X10 to power the DC components under maintenance.

[0049] In this utility model, the first maintenance socket group X3-X8 and the second maintenance socket group X9-X10 are all circular maintenance sockets, which are compatible with standard maintenance plugs to ensure the reliability of power supply during maintenance.

[0050] The workflow of this utility model is as follows:

[0051] Taking "starting AC36V maintenance power supply" as an example, the workflow is as follows:

[0052] 1. Move the main body of the maintenance platform to the target position and connect it to 220V AC power through the AC power input unit.

[0053] 2. When circuit breaker Q1 is closed, the main power protection unit is activated, and the live wire L supplies power to each branch circuit via circuit breaker Q1 and fuse F1.

[0054] 3. Press the start normally open switch S2, the first branch control circuit is turned on, the coil of relay K1 is energized, and its contacts close to achieve "self-locking".

[0055] 4. Close the relay K2 of the corresponding branch. The AC36V power supply is output through the first maintenance socket group X3-X8. Fix the component to be maintained on the rotating platform 3 through the electrical card holder 4 and connect it to the X3-X8 socket to start maintenance.

[0056] 5. In case of emergency, press the emergency stop normally closed switch S1 to disconnect the control circuit, de-energize relay K1, and immediately stop the AC36V power supply.

[0057] For the second voltage conversion branch, with relay K1 energized, the adjustable AC transformer T2 adjustment knob on the side of the main body 1 of the maintenance platform should be rotated to the target voltage. When the branch current is normal, the normally closed thermal overload protection switch S3 should remain closed, energizing relay K2 to output adjustable AC. The DC power conversion branch sets the output voltage via the adjustable voltage LCD display 8 on the operation panel 2, and supplies power to DC components in conjunction with the overload protection of the normally closed thermal overload protection switch S4. During soldering, solder wire is taken from the solder wire reel 5, the soldering iron is placed on the soldering iron holder 6, and the voltmeter 7 displays the output voltage in real time, ensuring visualization and safety during maintenance.

[0058] Through the coordinated design of structure and circuit, this utility model can safely and flexibly provide multi-specification maintenance power supplies for different electrical components, while improving the convenience of maintenance operations by means of structural components such as rotating platforms and card slots.

[0059] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to implement or use this invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this invention. Therefore, this invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electrical component inspection bench, characterized in that, include: The main body of the maintenance platform (1) provides a support carrier for the entire maintenance platform. An emergency stop normally closed switch S1 is installed on the platform surface, and an adjustment knob for the adjustable AC transformer T2, a thermal overload protection normally closed switch S3 and a thermal overload protection normally closed switch S4 are integrated on the side. The operation panel (2) is located on the upper part of the main body (1) of the maintenance platform and integrates circuit breaker Q1, fuse F2, fuse F3 and display components; A rotating platform (3) is installed on the table surface of the main body (1) of the inspection platform, used to place electrical components to be inspected and can be rotated to adjust the angle; Electrical bracket (4) is located on the edge of the rotating platform (3) and is used to clamp and fix the electrical components to be repaired; Solder wire reel (5) is set on the table surface of the main body (1) of the inspection table and is used to wind and place solder wire; Soldering iron holder (6) is set on the table surface of the main body (1) of the inspection table and is used to place soldering iron; A voltmeter (7) is embedded in the operation panel (2) and is used to display the voltage value output by the maintenance bench; An adjustable voltage liquid crystal display (8) is embedded in the operation panel (2) and is used to display the output voltage parameters of the adjustable AC transformer T2; The internal circuit system includes an AC power input unit, a main power protection unit, a first voltage conversion branch, a second voltage conversion branch and a DC power conversion branch. All of the above components are electrically connected inside the main body (1) of the maintenance platform by wires and are output through the X3-X10 sockets on the table surface of the main body (1).

2. The electrical component repair bench according to claim 1, characterized in that, The surface of the main body (1) of the inspection platform is made of anti-static insulating material.

3. The electrical component repair bench according to claim 1, characterized in that, The rotating platform (3) is an electric rotating platform with a stepper motor and an angle positioning mechanism inside. It can rotate and position steplessly within the range of 0-360°. The table surface of the rotating platform (3) is made of anti-static insulating material.

4. The electrical component repair bench according to claim 1, characterized in that, The bottom of the main body (1) of the maintenance platform is provided with several steering wheels for moving the main body (1).

5. A circuit system according to claim 1, characterized in that, include: The AC power input unit has a neutral terminal X1 and a live terminal X2 for connecting to an AC / DC converter. The main power protection unit includes a circuit breaker Q1 and a fuse F1 connected in series between the live wire terminal X2 and the subsequent circuit. The circuit breaker Q1 is used for manually disconnecting the main power supply of the main circuit, and the fuse F1 is used for short circuit protection of the main circuit. The first voltage conversion branch includes a step-down transformer T1, a fuse F2, an emergency stop normally closed switch S1, a start normally open switch S2, relays K1 and K2 (three sets of contacts), and a first maintenance socket group X3-X8. The primary side of the step-down transformer T1 is connected to the AC power input unit, and the secondary side outputs low-voltage AC power. The fuse F2 is connected in series between the secondary output terminal of the step-down transformer T1 and the emergency stop normally closed switch S1. The coils of the emergency stop normally closed switch S1, the start normally open switch S2, and the relay K1 are connected in series to the secondary circuit of the step-down transformer T1, and one set of contacts of the relay K1 is connected in parallel with the start normally open switch S2 to form a self-locking circuit. The three sets of contacts of the relay K2 are connected in parallel in the secondary circuit of the step-down transformer T1, with both ends of each set of contacts connected to one end of the first maintenance socket group X3-X8. The other end of the first maintenance socket group X3-X8 is connected to the secondary circuit of the step-down transformer T1. The second voltage conversion branch includes an adjustable AC transformer T2, a normally closed thermal overload protection switch S3, a fuse F3, another set of contacts of relay K1, and relay K2; wherein, the input terminal of the adjustable AC transformer T2 is connected to the AC power input unit, and the output terminal is connected to the output circuit of the adjustable AC transformer T2 via the fuse F3, the other set of contacts of relay K1, and the coil of relay K2 in series; the normally closed thermal overload protection switch S3 is connected in series between the input terminal of the adjustable AC transformer T2 and the fuse F1 of the main power protection unit; The DC power conversion branch includes an AC / DC converter, a normally closed thermal overload protection switch S4, and a second maintenance socket group X9-X10; wherein, the AC input terminal of the AC / DC converter is connected to the AC power input unit, and the DC output terminal outputs an adjustable voltage; the normally closed thermal overload protection switch S4 is connected in series between the AC input terminal of the AC / DC converter and the fuse F1 of the main power protection unit; the DC positive output terminal of the AC / DC converter is directly connected to the positive socket X9 of the second maintenance socket group; the DC negative output terminal of the AC / DC converter is directly connected to the negative socket X10 of the second maintenance socket group.

6. The circuit system according to claim 5, characterized in that, The first maintenance socket group X3-X8 and the second maintenance socket group X9-X10 are circular maintenance sockets, which are adapted to standard maintenance plugs to connect electrical components to be maintained.

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