Equipment for testing insulation resistance

Abstract

The utility model provides a device for testing insulation resistance, which is characterized in that the device comprises a first isolation switch connected to a three-phase circuit; a power supply module connected to the upstream of the first isolation switch on the three-phase circuit and configured to supply power to the measurement module, the processing module and the interface module; a measurement module connected to the downstream of the first isolation switch on the three-phase circuit and configured to measure a voltage signal corresponding to the insulation resistance of the three-phase circuit; a processing module configured to receive the voltage signal from the measurement module and determine whether the insulation resistance of the three-phase circuit is qualified based on the received voltage signal; an interface module is configured to receive user input directly or via a remote device.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of equipment for testing insulation impedance, and specifically, a kind of equipment for testing whether the insulation impedance of three-phase circuit is qualified. BACKGROUND

[0002] Insulation impedance refers to the electrical insulation state between each electrical equipment and power grid loop in the circuit. The higher the insulation impedance, the stronger the electrical insulation capability between electrical appliances, and the more stable the electrical equipment. In the circuit, whether the insulation between each electrical equipment is good has a great influence on the stability, safety, durability and other aspects of the circuit. Therefore, the insulation impedance between electrical equipment and power grid loop needs to be tested regularly.

[0003] Currently, the insulation impedance test between power grid loops is operated by maintenance personnel using a direct-current swing meter at each equipment work site, which has a certain risk of electric shock. In addition, for situations such as the subway industry where a large number of devices are deployed and the deployment distance is relatively far, if insulation impedance testing is performed, a large amount of manpower and time is required to complete, which brings a lot of inconvenience to daily maintenance. Therefore, the present disclosure proposes a device for testing insulation impedance, which can remotely control the device to test when the maintenance personnel test the insulation impedance, not only saving manpower and maintenance time, but also making daily maintenance safer. SUMMARY

[0004] According to an aspect of the utility model, a device for testing insulation impedance is provided, characterized in that the device comprises: a first disconnecting switch connected to a three-phase circuit; a power supply module connected upstream of the first disconnecting switch on the three-phase circuit and configured to supply power to a measurement module, a processing module, and an interface module; a measurement module connected downstream of the first disconnecting switch on the three-phase circuit and configured to measure a voltage signal corresponding to the insulation impedance of the three-phase circuit; a processing module configured to receive the voltage signal from the measurement module and determine whether the insulation impedance of the three-phase circuit is qualified based on the received voltage signal; and an interface module configured to receive user input directly or via a remote device.

[0005] In some examples, the measurement module includes a trigger, a selection unit, a current sensor, and an operational amplifier, wherein the current sensor is connected to the three-phase circuit via the selection unit, and wherein the operational amplifier samples and amplifies the voltage signal difference across the current sensor to generate a voltage signal corresponding to the insulation impedance of the three-phase circuit.

[0006] In some examples, the trigger is configured to receive a test signal from the processing module and send a drive signal to the selection unit based on the received test signal. The selection unit is configured to connect the current sensor to the first and second phase lines of the three-phase circuit, the second and third phase lines, the first and third phase lines, and the first, second, and third phase lines and the grounding protection line, respectively, based on the drive signal.

[0007] In some examples, the voltage signal includes a voltage signal corresponding to the insulation impedance between the first phase line and the second phase line, a voltage signal corresponding to the insulation impedance between the second phase line and the third phase line, a voltage signal corresponding to the insulation impedance between the first phase line and the third phase line, and a voltage signal corresponding to the insulation impedance between the first phase line, the second phase line, the third phase line and the grounding conductor.

[0008] In some examples, current sensors include resistors, current transformers (CTs), Rogowski coils, or Hall effect devices.

[0009] In some examples, the selection unit includes a channel selector, a relay, or a mechanical switch.

[0010] In some examples, the processing module is also configured to: determine that the insulation impedance of the three-phase circuit is unqualified based on the received voltage signal being greater than a threshold voltage; and determine that the insulation impedance of the three-phase circuit is qualified based on the received voltage signal being less than a threshold voltage.

[0011] In some examples, the power module includes a rectifier unit and a transformer unit, wherein the rectifier unit is connected upstream of a first disconnecting switch in a three-phase circuit and is configured to perform AC-DC conversion on AC power received from the three-phase circuit and boost it to a first voltage value, and wherein the transformer unit is connected to the rectifier unit and is configured to step down the voltage received from the rectifier unit to a second voltage value.

[0012] In some examples, the power module is configured to provide a power signal with a second voltage value to the processing module and the interface module, and to provide both a power signal with a first voltage value and a power signal with a second voltage value to the measurement module.

[0013] In some examples, the device further includes a second isolating switch connected between the power module and the measurement module.

[0014] In some examples, during insulation resistance testing, the first disconnecting switch is open and the second disconnecting switch is closed; after the test, the first disconnecting switch is closed and the second disconnecting switch is open.

[0015] In some examples, the interface module is also configured to send a start signal to the processing module based on received user input, and the processing module is also configured to send a test signal to the measurement module based on the start signal received from the interface module.

[0016] In some examples, the processing module is also configured to send a signal to the interface module indicating whether the insulation impedance of the three-phase circuit is qualified, and the interface module is also configured to provide information on whether the insulation impedance of the three-phase circuit is qualified, directly or via a remote device, based on receiving the signal indicating whether the insulation impedance of the three-phase circuit is qualified. Attached Figure Description

[0017] The aspects, features, and advantages of this utility model will become clearer and more readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0018] Figure 1 This is a schematic block diagram illustrating an apparatus for testing the insulation resistance of a three-phase circuit according to an embodiment of the present disclosure;

[0019] Figure 2 This is a schematic structural diagram illustrating an implementation of an apparatus for testing the insulation impedance of a three-phase circuit according to an embodiment of the present disclosure. Detailed Implementation

[0020] The present invention will now be described in detail with reference to exemplary embodiments thereof. However, the present invention is not limited to the embodiments described herein, and may be embodied in many different forms. The described embodiments are only intended to thoroughly and completely convey the concept of the present invention to those skilled in the art. Features of the various described embodiments may be combined with or substituted for each other, unless expressly excluded or should be excluded based on the context.

[0021] In the embodiments of this utility model, unless otherwise explicitly stated, "connection" or "connection" does not necessarily mean "direct connection" or "direct contact," but only requires electrical connection. Furthermore, the terms "first," "second," or similar expressions used herein are for descriptive and distinguishing purposes only and do not indicate any priority or order, nor should they be construed as indicating or implying the relative importance of the corresponding components, nor do they represent whether the described parameter values ​​are the same or different.

[0022] Figure 1 This is a schematic block diagram illustrating an apparatus for testing the insulation impedance of a three-phase circuit according to an embodiment of the present disclosure.

[0023] refer to Figure 1 The device 100 for testing the insulation resistance of a three-phase circuit may include a power supply module 110, a measurement module 120, a processing module 130, a first disconnecting switch 140, and an interface module 150.

[0024] The first disconnecting switch 140 is connected to the three-phase circuit. In some embodiments, the first disconnecting switch 140 is disconnected when the device is testing the insulation resistance of the three-phase circuit.

[0025] The power module 110 is connected upstream of the first disconnect switch 140 on the three-phase circuit and is configured to supply power to the measurement module, processing module, and interface module. In some embodiments, the power module may include a rectifier unit and a transformer unit. The rectifier unit may be connected upstream of the first disconnect switch 140 on the three-phase circuit and is configured to convert alternating current received from the three-phase circuit into direct current and boost it to a first voltage value. The transformer unit may be connected to the rectifier unit and is configured to step down the voltage received from the rectifier unit to a second voltage value. The first voltage value is greater than the second voltage value.

[0026] In some embodiments, the power module 110 may provide a power supply voltage having a second voltage value to the processing module 130 and the interface module 150, and provide both a power supply voltage having a first voltage value and a power supply voltage having a second voltage value to the measurement module.

[0027] Measurement module 120 is connected downstream of the first disconnect switch 140 on the three-phase circuit and is configured to measure a voltage signal corresponding to the insulation impedance of the three-phase circuit. In some embodiments, measurement module 120 may include a trigger, a selection unit, a current sensor, and an operational amplifier. The current sensor may be connected to the three-phase circuit via the selection unit, and the operational amplifier may sample and amplify the voltage signal difference across the current sensor to generate a voltage signal corresponding to the insulation impedance of the three-phase circuit.

[0028] In some embodiments, the trigger can receive a test signal from the processing module 130 and send a drive signal to the selection unit, so that the selection unit connects the current sensor to the three-phase circuit between the first phase line and the second phase line, between the second phase line and the third phase line, between the first phase line and the third phase line, and between the first phase line, the second phase line, the third phase line and the grounding protection line, respectively. The operational amplifier can sample and amplify the voltage signal difference across the current sensor to generate voltage signals corresponding to the insulation impedance between the first phase line and the second phase line, the insulation impedance between the second phase line and the third phase line, the insulation impedance between the first phase line and the third phase line, and the insulation impedance between the first phase line, the second phase line, the third phase line and the grounding protection line, respectively.

[0029] The processing module 130 is configured to receive a voltage signal from the measurement module 120 and determine whether the insulation impedance of the three-phase circuit is qualified based on the received voltage signal. In some embodiments, the processing module 130 may be configured to determine that the insulation impedance of the three-phase circuit is unqualified based on the received voltage signal being greater than a threshold voltage, and to determine that the insulation impedance of the three-phase circuit is qualified based on the received voltage signal being less than a threshold voltage.

[0030] Specifically, when the current sensor of the measurement module 120 is connected between the first and second phase lines of the three-phase circuit, the processing module 130 can determine whether the insulation impedance between the first and second phase lines of the three-phase circuit is qualified based on the voltage signal received from the measurement module 120. Similarly, when the current sensor of the measurement module 120 is connected between the second and third phase lines, between the first and third phase lines, and between the first, second, and third phase lines and the grounding protection line, respectively, the processing module 130 can determine whether the insulation impedance between the second and third phase lines, between the first and third phase lines, and between the first, second, and third phase lines and the grounding protection line of the three-phase circuit is qualified based on the voltage signal received from the measurement module 120.

[0031] In some embodiments, the processing module 130 may receive a start signal from the interface module 150 indicating the commencement of an insulation resistance test, and send a test signal to the measurement module 120 based on the received start signal. In some embodiments, the processing module 130 may also provide information indicating whether the insulation resistance of the three-phase circuit is qualified to the interface module 150. The processing module 130 may be implemented as a microcontroller unit (MCU); however, this disclosure is not limited thereto, and the processing module 130 may be implemented as any suitable device.

[0032] Interface module 150 can be configured to directly receive user input and send a start signal to processing module 130 indicating the start of insulation resistance testing. In some embodiments, interface module 150 can also be configured to receive information from processing module 130 indicating whether the insulation resistance of the three-phase circuit is qualified and provide this information to the user.

[0033] In some embodiments, the interface module 150 can be implemented as a human-machine interface (HMI). For example, the interface module 150 can be implemented as a touchscreen, where the user provides input via touch, and the interface module 150 presents the insulation resistance test results to the user via the touchscreen. As another example, the interface module 150 can be implemented as buttons and indicator lights, where the user provides input via buttons, and the indicator lights present the insulation resistance test results to the user; for example, green indicates acceptable insulation resistance, and red indicates unacceptable insulation resistance. However, this disclosure is not limited to these embodiments, and the interface module 150 can be implemented as any device capable of interacting with a user.

[0034] The interface module 150 can also be configured to receive user input via a remote device and send a start signal to the processing module 130 indicating the start of an insulation resistance test. In some embodiments, the interface module 150 can also be configured to receive information from the processing module 130 indicating whether the insulation resistance of the three-phase circuit is qualified, and send the information to the remote device to present the test results to the user.

[0035] In some embodiments, the interface module 150 can be implemented as a transceiver. For example, the device 100 for testing the insulation resistance of a three-phase circuit can be controlled by a remote device physically located away from the device 100, such as a console or host. When the insulation resistance of the three-phase circuit needs to be tested, the user can provide user input through the remote device, and the interface module 150 can receive the user input from the console. Furthermore, the interface module 150 can send the test results to the remote device to present the insulation resistance test results to the user. However, this disclosure is not limited thereto, and the interface module 150 can be implemented as any device capable of communicating with a remote device.

[0036] Figure 2 This is a schematic structural diagram illustrating an implementation of a device 200 for testing the insulation resistance of a three-phase circuit according to an embodiment of this disclosure. Figure 2 As shown, the power module 210 can correspond to Figure 1 The power module 110 and the measurement module 220 can correspond to Figure 1 The measurement module 120 and processing module 230 can correspond to Figure 1 The processing module 130, the first disconnect switch 240 can correspond to Figure 1 The first disconnecting switch 140, and the interface module 250 can correspond to Figure 1 Interface module 150.

[0037] refer to Figure 2The three-phase circuit includes a first phase line L1, a second phase line L2, a third phase line L3, and a protective earth line PE. A first disconnecting switch 240 is connected to the first phase line L1 through the third phase line L3 of the three-phase circuit. When the device 200 tests the insulation resistance of the three-phase circuit, the first disconnecting switch 240 is open, and when the test is completed, the first disconnecting switch 240 is closed. In some embodiments, the first disconnecting switch 240 can be manually opened or closed by the user.

[0038] The power module 210 includes a rectifier unit 210-1 and a transformer unit 210-2.

[0039] The first input terminal Vin1 and the second input terminal Vin2 of rectifier unit 210-1 are respectively connected to the first phase line L1 and the second phase line L2. However, this disclosure is not limited thereto; the first input terminal Vin1 and the second input terminal Vin2 of rectifier unit 210-1 can be connected to any two different phase lines L1 to L3 of the three-phase circuit. The output terminal Vout of rectifier unit 210-1 is connected to the input terminal Vin of transformer unit 210-2. Rectifier unit 210-1 can convert the alternating current received from the three-phase circuit into direct current and boost it to a first voltage value. In some embodiments, the first voltage value can be the voltage value required to test the insulation resistance of the three-phase circuit. Rectifier unit 210-1 can provide a power signal with the first voltage value to measurement module 220.

[0040] Transformer unit 210-2 can step down the power signal with a first voltage value received from rectifier unit 210-1 to a power signal with a second voltage value, and provide the power signal with the second voltage value to measurement module 220, processing module 230 and interface module 250 respectively. Although Figure 2 Although not shown in the figure, in some embodiments, the transformer unit 210-2 can provide a power signal with a second voltage value to the trigger 220-1 of the measurement module 220.

[0041] The measurement module 220 may include a trigger 220-1, a selection unit 220-2, a current sensor 220-3, and an operational amplifier U.

[0042] The current sensor 220-3 is connected to the three-phase circuit via the selection unit 220-2. The trigger 220-1 can be configured to receive a test signal from the processing module 230 and send a drive signal to the selection unit 220-2, such that the selection unit 220-2 connects the current sensor 220-3 between the first phase line L1 and the second phase line L2, between the second phase line L2 and the third phase line L3, between the first phase line L1 and the third phase line L3, and between the first phase line L1, the second phase line L2, the third phase line L3 and the protective earth line PE.

[0043] like Figure 2 As shown, the selection unit 220-2 is implemented as a combination of four double-pole double-throw switches S1 to S4, and the current sensor 220-3 is implemented as a resistor. The trigger 220-1 can be configured to send drive signals to the switches S1 to S4 of the selection unit 220-2 respectively, causing the switches S1 to S4 to close and open sequentially.

[0044] Specifically, when the interface module 250 receives user input directly or via a remote device, it can send a start signal to the processing module 230 to indicate the start of testing the insulation resistance of the three-phase circuit. The processing module 230 can send a first test signal to the trigger 220-1. Based on receiving the first test signal, the trigger 220-1 sends a first drive signal to the selection unit 220-2, causing the switch S1 to close. When the switch S1 is closed, the current sensor 220-3 is connected between the first phase line L1 and the third phase line L3, and the rectifier unit 210-1 can provide a power signal with a first voltage value to the first phase line L1 and the third phase line L3. The operational amplifier U can sample and amplify the voltage signal difference across the current sensor 220-3 to generate a first voltage signal corresponding to the insulation resistance between the first phase line L1 and the third phase line L3. Accordingly, the processing module 230 can receive the first voltage signal from the operational amplifier U of the measurement module 220, and determine whether the insulation impedance between the first phase line L1 and the third phase line L3 is qualified based on the comparison between the first voltage signal and the threshold voltage, and can send the test result to the interface module 250. The interface module 250 can directly present the test result to the user or send the test result to a remote device to present the test result to the user. After the insulation impedance test between the first phase line L1 and the third phase line L3 is completed, the trigger 220-1 can send a signal to the selection unit 220-2 to open the switch S1.

[0045] Subsequently, the processing module 230 can send a second test signal to the trigger 220-1. Based on the received second test signal, the trigger 220-1 sends a second drive signal to the selection unit 220-2, causing the switch S2 to close. When the switch S2 is closed, the current sensor 220-3 is connected between the second phase line L2 and the third phase line L3, and the rectifier unit 210-1 can provide a power signal with a first voltage value to the second phase line L2 and the third phase line L3. The operational amplifier U can sample and amplify the voltage signal difference across the current sensor 220-3 to generate a second voltage signal corresponding to the insulation impedance between the second phase line L2 and the third phase line L3. Accordingly, the processing module 230 can receive the second voltage signal from the operational amplifier U of the measurement module 220, and based on the comparison of the second voltage signal with a threshold voltage, determine whether the insulation impedance between the second phase line L2 and the third phase line L3 is qualified, and can send the test result to the interface module 250. The interface module 250 can directly present the test results to the user or send the test results to a remote device to present the test results to the user. After the insulation impedance test between the second phase line L2 and the third phase line L3 is completed, the trigger 220-1 can send a signal to the selection unit 220-2 to open the switch S2.

[0046] Similarly, processing module 230 can send a third test signal to trigger 220-1. Based on the received third test signal, trigger 220-1 sends a third drive signal to selection unit 220-2, causing switch S3 to close. When switch S3 is closed, current sensor 220-3 is connected between the first phase line L1 and the second phase line L2, and rectifier unit 210-1 can provide a power signal with a first voltage value to the first phase line L1 and the second phase line L2. Operational amplifier U can sample and amplify the voltage signal difference across current sensor 220-3 to generate a third voltage signal corresponding to the insulation impedance between the first phase line L1 and the second phase line L2. Accordingly, processing module 230 can receive the third voltage signal from operational amplifier U of measurement module 220, and based on a comparison of the third voltage signal with a threshold voltage, determine whether the insulation impedance between the first phase line L1 and the second phase line L2 is qualified, and can send the test result to interface module 250. The interface module 250 can directly present the test results to the user or send the test results to a remote device to present the test results to the user. After the insulation impedance test between the first phase line L1 and the second phase line L2 is completed, the trigger 220-1 can send a signal to the selection unit 220-2 to open the switch S3.

[0047] Furthermore, the processing module 230 can also send a fourth test signal to the trigger 220-1. Based on receiving the fourth test signal, the trigger 220-1 sends a fourth drive signal to the selection unit 220-2, causing the switch S4 to close. When the switch S4 is closed, the current sensor 220-3 is connected between the grounding protection line PE and the first phase line L1, the second phase line L2, and the third phase line L3, and the rectifier unit 210-1 can provide a power signal with a first voltage value to the grounding protection line PE and the first phase line L1, the second phase line L2, and the third phase line L3. The operational amplifier U can sample and amplify the voltage signal difference across the current sensor 220-3 to generate a fourth voltage signal corresponding to the insulation impedance between the grounding protection line PE and the first phase line L1, the second phase line L2, and the third phase line L3. Accordingly, the processing module 230 can receive the fourth voltage signal from the operational amplifier U of the measurement module 220, and based on the comparison of the fourth voltage signal with the threshold voltage, determine whether the insulation impedance between the protective earth conductor PE and the first phase line L1, the second phase line L2, and the third phase line L3 is qualified, and can send the test results to the interface module 250. The interface module 250 can directly present the test results to the user or send the test results to a remote device to present the test results to the user. After the insulation impedance test between the protective earth conductor PE and the first phase line L1, the second phase line L2, and the third phase line L3 is completed, the trigger 220-1 can send a signal to the selection unit 220-2 to open the switch S4.

[0048] It should be noted that, although Figure 2 The selection unit 220-2 is shown as a combination of four double-pole double-throw switches, but this disclosure is not limited thereto. In some embodiments, the selection unit 220-2 may be implemented as a multi-contact contactor, such that the current sensor 220-3 is connected, according to the drive signal of the trigger 220-1, between the first phase line L1 and the second phase line L2, between the second phase line L2 and the third phase line L3, between the first phase line L1 and the third phase line L3, and between any phase line and the protective earth line PE. In other embodiments, the selection unit 220-2 may be implemented as a channel selector or a combination of multiple mechanical switches.

[0049] In addition, although Figure 2 The current sensor 220-3 is shown as a resistor, but this disclosure is not limited thereto. In some embodiments, the current sensor 220-3 may be implemented as a current transformer (CT), a Rogowski coil, or a Hall effect device.

[0050] In some embodiments, the device 200 for testing the insulation resistance of a three-phase circuit may further include a second disconnect switch 260. The second disconnect switch 260 may be connected between the power supply module 210 and the measurement module 220. Specifically, the second disconnect switch 260 may be connected between the rectifier unit 210-1 of the power supply module 210 and the measurement module 220. When the device 200 tests the insulation resistance of the three-phase circuit, the second disconnect switch 260 closes, causing the power supply module 210 to provide a power signal with a first voltage value to the measurement module 220, and when the test is completed, the second disconnect switch 260 opens. In some embodiments, the second disconnect switch 260 may be manually opened or closed by a user.

[0051] It should be noted that, for clarity and simplicity, only the parts related to the embodiments of the present invention are shown in the accompanying drawings. However, those skilled in the art should understand that the devices or apparatus shown in the drawings may include other necessary elements.

[0052] The block diagrams of circuits, devices, apparatuses, equipment, and systems involved in this utility model are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these circuits, devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner that achieves the desired purpose. The quantities involved in this utility model are merely illustrative.

[0053] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0054] In the embodiments provided in this application, it should be understood that the disclosed systems and devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0055] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0056] Furthermore, in the various embodiments of this utility model, the functional units can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0057] Those skilled in the art should understand that the specific embodiments described above are merely examples and not limitations. Various modifications, combinations, partial combinations, and substitutions can be made to the embodiments of this utility model according to design requirements and other factors, as long as they are within the scope of the appended claims or their equivalents, and thus fall within the scope of the rights to be protected by this utility model.

Claims

1. A device for testing insulation resistance, characterized in that, The device includes: The first disconnecting switch is connected to the three-phase circuit; The power supply module is connected upstream of the first isolating switch on the three-phase circuit and is configured to supply power to the measurement module, processing module and interface module; The measurement module is connected downstream of the first disconnecting switch on the three-phase circuit and is configured to measure the voltage signal corresponding to the insulation impedance of the three-phase circuit. The processing module is configured to receive voltage signals from the measurement module and determine whether the insulation impedance of the three-phase circuit is qualified based on the received voltage signals; The interface module is configured to receive user input directly or via a remote device.

2. The device according to claim 1, characterized in that, The measurement module includes a trigger, a selection unit, a current sensor, and an operational amplifier. The current sensor is connected to the three-phase circuit via a selection unit, and The operational amplifier samples and amplifies the voltage signal difference across the current sensor to generate a voltage signal corresponding to the insulation impedance of the three-phase circuit.

3. The device according to claim 2, characterized in that, The trigger is configured to receive a test signal from the processing module and, based on the received test signal, send a drive signal to the selection unit. The selection unit is configured to connect current sensors to the first and second phase lines, the second and third phase lines, the first and third phase lines, and the first, second, and third phase lines and the grounding protection line of the three-phase circuit, respectively, based on the drive signal.

4. The device according to claim 3, characterized in that, The voltage signal includes a voltage signal corresponding to the insulation impedance between the first phase line and the second phase line, a voltage signal corresponding to the insulation impedance between the second phase line and the third phase line, a voltage signal corresponding to the insulation impedance between the first phase line and the third phase line, and a voltage signal corresponding to the insulation impedance between the first phase line, the second phase line, the third phase line and the grounding protection line.

5. The device according to claim 2, characterized in that, The current sensor includes a resistor, a current transformer (CT), a Rogowski coil, or a Hall effect device.

6. The device according to claim 2, characterized in that, The selection unit includes a channel selector, a relay, or a mechanical switch.

7. The device according to claim 1, characterized in that, The processing module is also configured to: Based on the received voltage signal exceeding the threshold voltage, it is determined that the insulation impedance of the three-phase circuit is unqualified; and Based on the fact that the received voltage signal is less than the threshold voltage, the insulation impedance of the three-phase circuit is determined to be qualified.

8. The device according to claim 1, characterized in that, The power module includes a rectifier unit and a transformer unit. The rectifier unit is connected upstream of the first isolating switch in the three-phase circuit and is configured to perform AC-DC conversion on the AC power received from the three-phase circuit and boost it to a first voltage value. The transformer unit is connected to the rectifier unit and is configured to step down the voltage received from the rectifier unit to a second voltage value.

9. The device according to claim 8, characterized in that, The power module is configured to provide a power signal with a second voltage value to the processing module and the interface module, and to provide both a power signal with a first voltage value and a power signal with a second voltage value to the measurement module.

10. The device according to claim 1, characterized in that, It also includes a second isolating switch, which is connected between the power module and the measurement module.

11. The device according to claim 10, characterized in that, During the insulation resistance test, the first disconnecting switch is open and the second disconnecting switch is closed. After the test, the first disconnecting switch is closed and the second disconnecting switch is open.

12. The device according to claim 1, characterized in that, The interface module is also configured to send a start signal to the processing module based on received user input, and The processing module is also configured to send a test signal to the measurement module based on the start signal received from the interface module.

13. The device according to claim 12, characterized in that, The processing module is also configured to send a signal to the interface module indicating whether the insulation impedance of the three-phase circuit is qualified, and The interface module is also configured to provide information on whether the insulation impedance of the three-phase circuit is qualified, either directly or via a remote device, based on the received signal indicating whether the insulation impedance of the three-phase circuit is qualified.

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