Automatic switching device for far-end compensation cable

Abstract

The utility model discloses the automatic switching device of remote compensation cable is provided in power supply test application technical field, disclose, including: PLC controller, N remote compensation cable, N remote compensation contactor, N test terminal, neutral cable, N remote compensation cable one end is connected with the positive pole of the compensation end of power supply, and the other end is connected with corresponding test terminal, and test terminal is used for connecting the positive pole of load, wherein, the voltage grade of every remote compensation cable is different, one end of neutral cable is connected with the negative pole of the compensation end of power supply, and the other end is used for connecting the negative pole of load, and PLC controller is used for receiving the switching instruction of cable and is outputted for respectively controlling the control signal of N remote compensation contactor, N remote compensation contactor all are connected with PLC controller, and are used for according to control signal and open or disconnect the corresponding remote compensation cable, and N is the integer greater than or equal to 2, thereby improve the safety and test efficiency of remote compensation test.

Description

Technical Field

[0001] This utility model relates to the field of power supply testing application technology, and in particular to an automatic switching device for remote compensation cables. Background Technology

[0002] Aircraft electrical and electronic equipment must operate stably within strictly defined voltage ranges. To verify their performance under real-world power supply conditions, power characteristic tests are required for airborne equipment. The power supply test involves applying the test voltage to the input terminal of the device under test (DUT) by switching between different test power supply circuits in the test cabinet, simulating different operating states of the aircraft's power supply system. However, due to the long cable and high impedance between the test power supply and the DUT, a significant voltage drop occurs, which can affect the test results.

[0003] Currently, voltage drop compensation is typically achieved using the remote sensitivity compensation function of the test power supply. This involves manually connecting the remote sensitivity compensation cable of the test power supply to the input terminal of the device under test (DUT) to compensate for voltage loss between the DUT and the power supply caused by cable impedance. However, this manual switching method has several drawbacks, including complex connection procedures, safety hazards, and low operational efficiency. Therefore, there is an urgent need for an automated device that eliminates the need for manual cable switching to improve the safety and efficiency of remote sensitivity compensation testing. Utility Model Content

[0004] The purpose of this utility model embodiment is to provide an automatic switching device for remote compensation cables to improve the safety and testing efficiency of remote sensitive compensation testing.

[0005] To solve the above-mentioned technical problems, an embodiment of this utility model provides an automatic switching device for remote compensation cables, comprising: a PLC controller, N remote compensation cables, N remote compensation contactors corresponding one-to-one with the N remote compensation cables, N test terminals corresponding one-to-one with the N remote compensation cables, and a neutral cable; one end of each of the N remote compensation cables is connected to the positive terminal of the compensation terminal of the power supply, and the other end is connected to the corresponding test terminal, which is used to connect to the positive terminal of the load; wherein, each remote compensation cable has a different voltage level; one end of the neutral cable is connected to the negative terminal of the compensation terminal of the power supply, and the other end is used to connect to the negative terminal of the load; the PLC controller is used to receive cable switching instructions and output control signals for controlling the N remote compensation contactors respectively; each of the N remote compensation contactors is connected to the PLC controller and is used to turn on or off the corresponding remote compensation cable according to the control signal; wherein, N is an integer greater than or equal to 2.

[0006] In this embodiment of the invention, after receiving an external switching command, the PLC controller can drive the remote compensation contactors corresponding to each of the N remote compensation cables, causing the remote compensation cable with a specific voltage level to conduct while the compensation cables of other voltage levels to disconnect. A compensation voltage is then applied to the load end through the corresponding test terminal, while the neutral cable ensures a closed negative circuit. This structure eliminates the need for manual replacement of compensation cables. By sending a switching command to the PLC controller, the most suitable remote compensation cable with the appropriate voltage level is selected, offsetting the voltage drop caused by the impedance of long-distance cables. This ensures a stable and accurate compensated test voltage is always provided to the load under test, effectively preventing connection errors or safety hazards caused by human error, and significantly improving testing efficiency and safety. Attached Figure Description

[0007] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0008] Figure 1 This is a structural diagram of an automatic switching device provided in an embodiment of the present invention; Figure 2 This is a circuit diagram of the automatic switching device provided in one embodiment of the present invention when near-end sensitivity compensation is enabled; Figure 3 This is a schematic diagram of the outer panel of an automatic switching device provided in an embodiment of the present invention; Figure 4 This is a circuit diagram of the automatic switching device provided in one embodiment of the present invention when 28V remote sensitive compensation is enabled; Figure 5 This is a circuit diagram of the automatic switching device provided in one embodiment of the present invention when 270V remote sensitive compensation is enabled; Figure 6 This is a circuit diagram of the automatic switching device provided in one embodiment of the present invention when 540V remote sensitive compensation is enabled. Detailed Implementation

[0009] In ground power characteristic testing of avionics equipment, it is necessary not only to simulate the voltage output of the aircraft power supply system under different operating conditions such as engine start-up, fuel pump operation, and rectifier switching, but also to ensure that the voltage obtained at the input terminal of the device under test (DUT) is always within a strictly rated range. To this end, the test system typically consists of a test power supply, a switching cabinet, and connecting cables several meters long. Different voltage circuits (such as 28 V, 270 V, and 540 V) are switched via contactors inside the cabinet to apply the standard test voltage to the input terminal of the DUT, thereby verifying its performance under various power supply conditions.

[0010] However, long-distance cables between the test power supply and the device under test (DUT) can cause significant voltage drops due to factors such as resistance, inductance, and poor contact. This is especially problematic during high-current testing, where the deviation between the actual DUT terminal voltage and the test power supply's set output voltage directly impacts the accuracy and repeatability of the test results. Therefore, ensuring accurate test results requires eliminating the voltage drop caused by long cables between the test power supply and the DUT. Currently, this is primarily achieved through remote sensing compensation. The principle is as follows: outside the standard test voltage loop, a pair of compensation cables suitable for the current voltage level feeds the voltage at the DUT back to the power supply control terminal in real time. The power supply dynamically adjusts its output voltage based on this feedback signal, thereby bringing the DUT terminal voltage closer to the set value.

[0011] Currently, in most scenarios, engineers must manually connect the "remote-sensitive compensation" cable to the test power supply to feed back the voltage at the tested end to the power supply, so that the output voltage can be automatically adjusted to compensate for cable losses. However, this "manual switching" method has several drawbacks: 1. The process is cumbersome and prone to errors: Every time the voltage level or the device under test is changed, the power must be manually turned off and the compensation cable plugged and unplugged. The operation steps are numerous and the compensation may fail or electrical faults may occur due to incorrect terminal connection or improper sequence.

[0012] 2. Safety and reliability risks: Frequent bare wire operations under high voltage conditions pose risks of electric shock, arc discharge, and the introduction of external electromagnetic interference, which not only threaten personnel safety but may also cause measurement errors and equipment damage.

[0013] 3. Inefficient: Manual switching requires interrupting the testing process, and the shutdown and reconnection severely slows down the verification progress, which is not conducive to batch or long-term continuous testing; moreover, it is impossible to achieve precise synchronization at the moment of switching, which makes it easy to miss key transient parameters.

[0014] To overcome the above problems, there is an urgent need for a device that can automatically switch remote compensation cables, achieve seamless automatic switching of compensation cables, significantly improve the safety, reliability and efficiency of the test system, and meet the high standards of accuracy and repeatability required for aviation power characteristic testing.

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the various embodiments of this utility model will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this utility model to help readers better understand this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments. The division of the various embodiments below is for the convenience of description and should not constitute any limitation on the specific implementation of this utility model. The various embodiments can be combined with and referenced by each other without contradiction.

[0016] One embodiment of this utility model relates to an automatic switching device for remote compensation cables, comprising: a PLC controller, N remote compensation cables, N remote compensation contactors corresponding one-to-one with the N remote compensation cables, N test terminals corresponding one-to-one with the N remote compensation cables, and a neutral cable; one end of each of the N remote compensation cables is connected to the positive terminal of the compensation terminal of the power supply, and the other end is connected to the corresponding test terminal, which is used to connect to the positive terminal of the load; wherein, each remote compensation cable has a different voltage level; one end of the neutral cable is connected to the negative terminal of the compensation terminal of the power supply, and the other end is used to connect to the negative terminal of the load; the PLC controller is used to receive cable switching instructions and output control signals for controlling the N remote compensation contactors respectively; each of the N remote compensation contactors is connected to the PLC controller and is used to turn on or off the corresponding remote compensation cable according to the control signal; wherein, N is an integer greater than or equal to 2. In this embodiment of the invention, after receiving an external switching command, the PLC controller can drive the remote compensation contactors corresponding to each of the N compensation cables, causing the compensation cable with a specific voltage level to conduct while the other compensation cables with different voltage levels are disconnected. Compensation voltage is then applied to the load end through the corresponding test terminals, while the neutral cable ensures a closed negative circuit. This structure eliminates the need for manual replacement of compensation cables. By sending a switching command to the PLC controller, the most suitable compensation cable with the correct voltage level is selected, offsetting voltage drops caused by long-distance cable impedance. This ensures a stable and accurate compensation voltage is always provided to the load under test, effectively preventing connection errors or safety hazards caused by human error, and significantly improving testing efficiency and safety.

[0017] The following is a detailed description of the implementation details of the automatic switching device for the remote compensation cable according to an embodiment of the present invention. The following implementation details are provided for ease of understanding only and are not necessary for implementing this solution.

[0018] Figure 1The automatic switching device according to an embodiment of the present invention is shown, including: a PLC controller, N remote compensation cables, N remote compensation contactors corresponding to the N remote compensation cables, N test terminals corresponding to the N remote compensation cables, and a neutral cable.

[0019] The PLC controller is used to receive cable switching instructions and output control signals for controlling the N remote compensation contactors respectively.

[0020] It is important to note that the PLC controller, as the core control unit, is responsible for receiving and processing external switching commands. When the test host issues a cable switching command, the PLC controller receives the command and connects to the remote compensation contactors via low-voltage signals to control the on and off states of each contactor. Specifically, when the PLC controller receives a command from the test host, it uses its built-in control logic to provide accurate control signals to each remote compensation cable, thereby achieving automatic connection and disconnection of the required voltage level compensation cable.

[0021] Furthermore, the PLC controller's control signals directly drive the contactors via low-voltage signals. Each remote compensation contactor corresponds to a compensation cable of a specific voltage level. Thus, when the PLC controller sends a switching command, the corresponding contactor automatically turns on or off based on the signal change, ensuring the selection of the appropriate compensation cable and its connection to the test circuit. In this way, whether it's 28V, 270V, or 540V, the system can automatically switch to the correct remote compensation cable, greatly improving the automation and efficiency of the test.

[0022] The PLC controller also features a network interface for receiving cable switching commands, enabling communication with the test host. Through the network interface, the test host can remotely send switching commands to the PLC controller, instructing it to switch to the appropriate voltage compensation cable based on different test requirements. This design not only improves system flexibility but also ensures the accuracy of the testing process, as the seamless communication between the test host and the PLC controller accurately transmits test requirements and reduces interference from human intervention.

[0023] Optionally, to further enhance system stability and flexibility, the layout of the test host is also flexible. The test host can be placed inside or outside the device as needed. When the test host is located outside the device, it communicates with the PLC controller and transmits switching commands via a network cable. This design simplifies and stabilizes the connection between the test host and the PLC controller, and facilitates remote operation, reducing the complexity of on-site operations. When the test host is located inside the device, it connects directly to the PLC controller and transmits switching commands. This method improves the command transmission speed of the test host, thereby achieving switching functionality more efficiently.

[0024] The N remote compensation cables have one end connected to the positive terminal of the power supply's compensation terminal, and the other end connected to the corresponding test terminal, which is used to connect to the positive terminal of the load. Each remote compensation cable has a different voltage rating. Specifically, the N remote compensation cables include 28V, 270V, and 540V compensation cables; the N remote compensation contactors include 28V, 270V, and 540V contactors; and the N test terminals include 28V, 270V, and 540V test terminals.

[0025] The N remote compensation contactors are all connected to the PLC controller and are used to turn on or off the corresponding remote compensation cables according to the control signal; where N is an integer greater than or equal to 2.

[0026] It is important to note that the N remote compensation cables are a key component in constructing the compensation loop. Their function is to compensate for voltage drops caused by factors such as cable resistance, thereby ensuring voltage accuracy during testing. Each remote compensation cable has a different voltage rating: 28V, 270V, and 540V. Each voltage rating is paired with a corresponding remote compensation contactor and test terminals. Specifically, the N remote compensation contactors include 28V, 270V, and 540V contactors, which are connected to the PLC controller to ensure that the corresponding voltage rating compensation cable is switched on and off according to control signals. In this way, the PLC controller can automatically select and activate the compensation cable that matches the load as needed, avoiding errors and safety hazards that may occur during manual switching.

[0027] Simultaneously, one end of the compensation cable is connected to the positive terminal of the power supply's compensation terminal, and the other end is connected to the positive terminal of the load via a corresponding test terminal. Each test terminal is labeled according to its voltage level, such as 28V, 270V, and 540V test terminals. Remote compensation cables for different voltage levels are connected to the PLC controller via remote compensation contactors, ensuring that only the compensation cable required for the current voltage level is connected, thus avoiding interference between different voltages.

[0028] One end of the neutral cable is connected to the negative terminal of the power supply's compensation terminal, and the other end is used to connect to the negative terminal of the load. Specifically, the function of the neutral cable is to establish a stable current loop between the load terminal and the negative terminal of the power supply, ensuring voltage stability during the compensation process.

[0029] In addition to the far-end compensation cable, the automatic switching device for the far-end compensation cable also includes: a neutral terminal connected to the neutral cable, a near-end compensation cable, and a near-end compensation contactor corresponding to the near-end compensation cable.

[0030] The neutral terminal is used to connect to the negative terminal of the load, and the neutral terminal is also used to connect to the negative terminal of the power supply terminal; the test terminal is also used to connect to the positive terminal of the power supply terminal.

[0031] Specifically, the design of the neutral terminal ensures the integrity of the system current loop and voltage stability. The neutral terminal connects not only to the negative terminal of the load but also to the negative terminal of the power supply, thus maintaining a stable current loop during compensation. The test terminals, in addition to connecting to the positive terminal of the load, are also used to connect to the positive terminal of the power supply to ensure the accuracy and stability of the test voltage.

[0032] The PLC controller also outputs a control signal for controlling the near-end compensation contactor; the near-end compensation cable is used to short-circuit the positive terminal of the compensation end of the power supply to the positive terminal of the power supply; the near-end compensation contactor is used to turn the near-end compensation cable on or off according to the control signal.

[0033] Based on the above, when switching the device to a state where remote compensation is disabled, the near-end compensation cable needs to be applied to the compensation circuit. Specifically, the near-end compensation cable is used to short-circuit the positive terminal of the compensation end of the power supply with the positive terminal of the power supply. Furthermore, the PLC controller plays a core role in the system, controlling not only the remote compensation contactor but also the operation of the near-end compensation contactor. By controlling the connection and disconnection of the near-end compensation cable, the PLC achieves coordinated operation with the remote compensation cable.

[0034] Optionally, the ends of the N far-end compensation cables connected to the positive terminal of the power supply's compensation terminal are connected in parallel to the near-end compensation cable. Specifically, to simplify the connection, the compensation terminals of all N far-end compensation cables can be connected in parallel to the same near-end compensation cable. By using a contactor to turn the cables on or off, any compensation cable can be flexibly switched to the positive circuit. In this way, all compensation cables can be concentrated inside the switching device, while only one near-end compensation cable needs to be connected at the power supply end, effectively simplifying the configuration of the compensation cables.

[0035] In addition, the automatic switching device for remote compensation cables also includes: a housing, the interior of which is used to house the PLC controller, the N remote compensation contactors and the N remote compensation cables, and the surface of the housing is provided with the N test terminals and the ground terminal.

[0036] Specifically, the automatic switching device for remote compensation cables also includes a housing designed to provide structural protection while facilitating the management and arrangement of internal components. The housing houses key components such as the PLC controller, N remote compensation contactors, and N remote compensation cables. By compactly integrating these components within the housing, the space occupied is effectively reduced, while ensuring good connection and operation between the various components.

[0037] The enclosure design takes into account factors such as component heat dissipation, ease of installation, and electrical isolation to ensure the stability and reliability of the device under different operating environments. The enclosure surface has N test terminals and a ground terminal, which are directly connected to the external load. The function of the test terminals is to provide a stable test voltage signal to the load, while the ground terminal is used to ensure a complete grounding loop between the power supply and the load, guaranteeing electrical safety.

[0038] This integrated design provides not only mechanical protection and structural support, but also convenient connectivity to external devices via surface-mount terminals. Furthermore, the internal wiring and component placement meet electrical safety requirements, ensuring accurate transmission and control of electrical signals while preventing electrical interference or signal attenuation.

[0039] Specifically, such as Figure 2 The internal enclosure integrates a PLC controller, contactors (such as KM4, KM5, KM6, KM7, KM8, and KM9), and various test and control cables. These components, through a compact arrangement and rational connection method, enable the system to operate efficiently. Figure 3The outer panel of the enclosure is equipped with flat-cap type test terminals, including DC28V, DC270V, DC540V, N, and PE terminals, facilitating connection to external devices. The enclosure surface also features a bottom-mounted cable inlet, signal interface, and network interface; the latter is used for communication with the test host, enabling remote control and monitoring.

[0040] In addition, the device includes a grounding terminal for connecting the grounding terminal of the power supply to the grounding terminal of the load, ensuring the electrical safety and stability of the entire system.

[0041] like Figure 2 In this embodiment, a switching cabinet is used in conjunction with the remote sensitive compensation automatic switching device when it is connected to the power supply. The function of the switching cabinet is to automatically switch the voltage level in the power supply circuit according to different test requirements, thereby achieving precise control of power output and input. Through connection with the PLC controller, the switching cabinet can quickly switch between different voltage levels, ensuring that the system can adapt to various power supply test conditions.

[0042] Specifically, the switching cabinet in this embodiment integrates multiple contactors (such as KM1, KM2, and KM3), which are used to switch the positive cable of the power supply circuit under the command of the PLC controller. Driven by PLC control signals, these contactors perform power circuit switching operations, thereby changing the voltage output level (e.g., 28V, 270V, 540V, etc.) to meet different testing requirements. This design allows the device to automatically switch different voltage outputs without manual operation, significantly improving testing efficiency and accuracy.

[0043] Based on the remote sensitivity compensation automatic switching device in the above-described embodiments of the present invention, it can achieve both no-compensation and remote compensation working states according to different testing requirements, as detailed below: 1. Situations where remote sensitive compensation is not required: such as Figure 2 As shown, when performing non-standard requirements testing or when the input voltage drop requirement of the device under test (DUT) is not high, the test host controls contactors KM4 and KM5 to remain normally closed via PLC. In this case, the remote sensitive compensation terminals (L, N) are shorted to the power output terminals (L, N), the test power supply is in near-end compensation mode, and the remote sensitive compensation function is not enabled. Depending on different power supply requirements, the DUT can be directly connected to the DC28V, DC270V, or DC540V test terminals for testing without the need for remote compensation.

[0044] 2. 28V remote sensitivity compensation: such as Figure 4As shown, according to standard requirements, when performing aircraft power supply characteristic tests on a 28V device under test (DUT), the test host controls the KM1 contactor to close via PLC, connecting the 28V test main circuit. Simultaneously, the PLC controls the KM4 and KM5 contactors to open and the KM6 and KM9 contactors to close. At this time, the 28V remote sensitive compensation cable is connected and the remote sensitive compensation function is activated. The 28V DUT is then connected to the DC 28V test terminal, and the test system provides compensation for the 28V voltage level.

[0045] 3. 270V remote sensitivity compensation: such as Figure 5 As shown, according to standard requirements, when performing aircraft power supply characteristic tests on a 270V device under test (DUT), the test host controls the KM2 contactor to close via PLC, connecting the 270V test main circuit. Simultaneously, the PLC controls the KM4 and KM5 contactors to open and the KM7 and KM9 contactors to close. At this time, the 270V remote sensitive compensation cable is connected and the remote sensitive compensation function is activated. The 270V DUT is connected to the DC 270V test terminal, and the test system provides compensation for the 270V voltage level.

[0046] 4. 540V remote sensitivity compensation: such as Figure 6 As shown, according to standard requirements, when performing aircraft power supply characteristic tests on a 540V device under test (DUT), the test host controls the KM3 contactor to close via PLC, connecting the 540V test main circuit. Simultaneously, the PLC controls the KM4 and KM5 contactors to open and the KM8 and KM9 contactors to close. At this time, the 540V remote sensitive compensation cable is connected and the remote sensitive compensation function is activated. The 540V DUT is connected to the DC 540V test terminal, and the test system provides compensation for the 540V voltage level.

[0047] Through these automated switching methods, the remote sensitive compensation automatic switching device can flexibly switch according to different voltage requirements, ensuring stable and accurate voltage compensation throughout the testing process. The compensation operation for each voltage level is precisely controlled by a PLC to manage the state of each contactor, achieving accurate compensation between the power supply and the load. This improves testing efficiency and accuracy, avoiding the complexity and safety hazards of traditional manual connection.

[0048] In this embodiment of the invention, after receiving an external switching command, the PLC controller can drive the remote compensation contactors corresponding to each of the N remote compensation cables, causing the remote compensation cable with a specific voltage level to conduct while the compensation cables of other voltage levels to disconnect. A test voltage is then applied to the load end through the corresponding test terminal, while the neutral cable ensures a closed negative circuit. This structure eliminates the need for manual replacement of compensation cables. By sending a switching command to the PLC controller, the most suitable remote compensation cable with the appropriate voltage level is selected, offsetting the voltage drop caused by the impedance of long-distance cables. This ensures a stable and accurate compensation voltage is always provided to the load under test, effectively preventing connection errors or safety hazards caused by human error, and significantly improving testing efficiency and safety.

[0049] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0050] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0051] Furthermore, the examples mentioned in the above embodiments can be freely combined, and any combination can be understood as an embodiment. The terms "embodiment" or "example" appearing in various locations in the specification do not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive with other embodiments. Those skilled in the art will understand that the embodiments described herein can be combined with other embodiments.

Claims

1. An automatic switching device for remote compensation cables, characterized in that, include: PLC controller, N remote compensation cables, N remote compensation contactors corresponding to the N remote compensation cables, N test terminals corresponding to the N remote compensation cables, and neutral cable. The N remote compensation cables are connected at one end to the positive terminal of the power supply compensation terminal and at the other end to the corresponding test terminal, which is used to connect to the positive terminal of the load; wherein, each remote compensation cable has a different voltage level. One end of the neutral cable is connected to the negative terminal of the compensation terminal of the power supply, and the other end is used to connect to the negative terminal of the load. The PLC controller is used to receive cable switching instructions and output control signals for controlling the N remote compensation contactors respectively. The N remote compensation contactors are all connected to the PLC controller and are used to turn on or off the corresponding remote compensation cables according to the control signal; where N is an integer greater than or equal to 2.

2. The automatic switching device for remote compensation cables according to claim 1, characterized in that, It also includes a neutral wire terminal connected to the neutral cable; The neutral terminal is used to connect to the negative terminal of the load.

3. The automatic switching device for remote compensation cables according to claim 2, characterized in that, The neutral terminal is also used to connect to the negative terminal of the power supply. The test terminal is also used to connect to the positive terminal of the power supply.

4. The automatic switching device for remote compensation cables according to claim 1, characterized in that, The automatic switching device also includes a near-end compensation cable and a near-end compensation contactor corresponding to the near-end compensation cable; The PLC controller also outputs control signals for controlling the proximal compensation contactor; The near-end compensation cable is used to short-circuit the positive terminal of the compensation end of the power supply to the positive terminal of the power supply. The near-end compensation contactor is used to turn the near-end compensation cable on or off according to the control signal.

5. The automatic switching device for remote compensation cables according to claim 4, characterized in that, One end of each of the N far-end compensation cables connected to the positive terminal of the power supply compensation terminal is connected in parallel to the near-end compensation cable.

6. The automatic switching device for remote compensation cables according to claim 1, characterized in that, It also includes a grounding terminal for connecting the grounding terminal of the power supply to the grounding terminal of the load.

7. The automatic switching device for remote compensation cables according to claim 6, characterized in that, It also includes a housing, the interior of which is used to house the PLC controller, the N remote compensation contactors and the N remote compensation cables, and the surface of the housing is provided with the N test terminals and the ground terminal.

8. The automatic switching device for remote compensation cables according to any one of claims 1 to 7, characterized in that, The N remote compensation cables include 28-volt compensation cables, 270-volt compensation cables and 540-volt compensation cables; The N remote compensation contactors include 28-volt, 270-volt, and 540-volt contactors; The N test terminals include 28V test terminals, 270V test terminals, and 540V test terminals.

9. The automatic switching device for remote compensation cables according to any one of claims 1 to 7, characterized in that, The PLC controller is equipped with a network interface, which is used to receive the cable switching command.

10. The automatic switching device for remote compensation cables according to any one of claims 1 to 7, characterized in that, It also includes a test host, which is connected to the PLC controller and is used to send the cable switching command to the PLC controller.

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