An insulation resistance tester with three same measurement functions

Abstract

The application provides an insulation resistance tester with three same measurement functions, comprising a control module, which converts an alternating current power supply signal according to a generated test instruction and outputs; a high-voltage package, which outputs a high-voltage direct current signal to a phase switcher and returns a low-voltage direct current signal to an inverter control circuit corresponding to the inverter; a phase switching unit, which connects the output end to an input end connected to a discharge resistance, and when receiving the high-voltage direct current signal, continuously connects the output end to the second input end, wherein the continuous connection is to maintain the corresponding connection state according to a preset test time value; and an insulation resistance measurement unit, which detects a current measurement value on the phase of the tested three-phase insulation resistance and judges whether the tested three-phase insulation resistance is normal. The application can complete the test work of the three-phase insulation resistance of the power equipment according to the specified time sequence and once wiring, has the ability of automatic pressurization and discharge, and eliminates the risk of electric arc injury.

Description

Technical Field

[0001] This invention relates to the field of resistance testing technology, and in particular to an insulation resistance tester with three-phase testing functions. Background Technology

[0002] Insulation resistance testers are widely used instruments for testing the insulation condition of power grids and electrical equipment, playing a crucial role in ensuring product quality and the safety of personnel and equipment during operation. The insulation resistance value of electrical equipment is an important parameter for evaluating its insulation performance. However, existing insulation resistance testers have relatively limited functions, especially lacking automation when testing different test objects.

[0003] Insulation resistance testing is a fundamental test in the power industry. Its working principle is to apply a high voltage DC voltage of 500-10000V to the equipment under test, measure the leakage current flowing through the equipment under test, calculate the resistance value of the equipment under test, and thus determine whether the insulation of the equipment under test is good.

[0004] Insulation resistance testers are relatively mature, but they still present several inconveniences in use. First, they are cumbersome to operate. Most electrical equipment consists of three phases (A, B, and C). During insulation resistance testing, each phase needs to be measured individually, with the tested phase connected to high voltage and the non-tested phases grounded. Traditional insulation resistance testers only have a single output, requiring manual reconnection and disconnection of the test leads, resulting in a large workload. Second, they have low safety. Electrical equipment often has a large capacitance. During insulation resistance measurement, the tested electrical equipment will store a large amount of charge under the test DC voltage. After the test, this charge needs to be released to ensure personal safety. Traditional insulation resistance testers lack sufficient discharge function, requiring manual discharge using a grounding wire. This method generates a large instantaneous arc, posing a safety hazard. Summary of the Invention

[0005] The purpose of this invention is to propose an insulation resistance tester with three-phase measurement functions, which solves the technical problems of existing testers requiring repeated manual disconnection and reconnection of test leads, resulting in a large workload and low safety.

[0006] On the one hand, an insulation resistance tester with three-phase measurement function is provided, including:

[0007] The control module contains at least one inverter, which converts the DC power supply signal into a corresponding AC power supply signal and outputs it according to the generated test command.

[0008] The high-voltage transformer converts the AC power supply signal output by the inverter into corresponding high-voltage DC signals and low-voltage DC signals, and outputs the high-voltage DC signals to the phase switcher and returns the low-voltage DC signals to the inverter control circuit corresponding to the inverter.

[0009] A phase switching unit is provided with at least three phase switchers. Each phase switcher is provided with at least one output terminal connected to the three-phase insulation resistance under test, a first input terminal connected to the high-voltage transformer, and a second input terminal connected to the discharge resistor. The phase switching unit connects the output terminal to the input terminal connected to the discharge resistor. When the high-voltage DC signal is received, the output terminal is continuously connected to the second input terminal. The continuous connection is maintained according to a preset test time value.

[0010] An insulation resistance measuring unit is connected to the corresponding phase of the tested three-phase insulation resistance. When the connection between the output terminal and the second input terminal ends, it detects the current measurement value on the corresponding phase of the tested three-phase insulation resistance and determines whether the tested three-phase insulation resistance is normal based on the current measurement value.

[0011] Preferably, the control module includes: a power supply unit, the inverter, and an inverter control circuit.

[0012] The inverter control circuit generates a corresponding PWM signal according to the received test command, and controls the inverter according to the PWM signal;

[0013] The power supply unit supplies the corresponding DC power supply signal to the inverter.

[0014] Preferably, the high-voltage package includes: a high-voltage transformer, a high-voltage rectifier bridge, and a protective resistor connected in sequence.

[0015] The high-voltage transformer boosts the input AC power supply signal to obtain a high-voltage AC signal with the corresponding voltage value.

[0016] The high-voltage rectifier bridge converts the high-voltage AC signal output by the high-voltage transformer into a high-voltage DC signal with a corresponding voltage value.

[0017] The protection resistor receives the high-voltage DC signal from the high-voltage rectifier bridge and outputs it to the first input terminal of the phase switch to ensure that the output current is within a preset safe current range.

[0018] Preferably, the high-voltage transformer further includes: a voltage divider resistor, the input of which is connected to the protective resistor, and the output of which is connected to both the inverter control circuit and the output voltage measurement circuit within the insulation resistance measurement unit.

[0019] The voltage divider resistor converts the high-voltage DC signal input at the input terminal into multiple corresponding low-voltage DC signals. One of the low-voltage DC signals powers the inverter control circuit, and another low-voltage DC signal is input as a measurement parameter to the output voltage measurement circuit.

[0020] Preferably, the phase switcher further includes a drive coil and switching electrode plates.

[0021] The drive coil is wound around the outside of the switching electrode plate, and the drive coil can drive the switching electrode plate to move according to the input DC voltage;

[0022] One end of the switching electrode is connected to the output terminal, and the other end of the switching electrode is disposed between the first input terminal and the second input terminal;

[0023] When there is no voltage in the drive coil, the switching electrode is connected to the second input terminal; when there is voltage in the drive coil, the switching electrode is connected to the first input terminal.

[0024] Preferably, the other end of the discharge resistor is connected to the zero-point phase set inside the high-voltage transformer. When there is voltage in the drive coil, the corresponding phase of the tested three-phase insulation resistance, the output terminal, the switching electrode, the first input terminal, the discharge resistor, and the zero-point phase are connected to form a discharge circuit for discharging the tested three-phase insulation resistance.

[0025] Preferably, the insulation resistance measuring unit includes: at least three insulation resistance measuring circuits and the output voltage measuring circuit.

[0026] The input terminal of the insulation resistance measurement circuit is connected to the corresponding phase of the tested three-phase insulation resistance and the output terminal of the output voltage measurement circuit, respectively. The input terminal of the output voltage measurement circuit is connected to the output terminal of the voltage divider resistor.

[0027] Preferably, the phase switcher is specifically used to, after the drive coil inside is energized, apply the high voltage DC signal to the corresponding phase of the tested three-phase insulation resistance through the switching electrode and the second input terminal connected to the switching electrode, and maintain the corresponding loading state according to the preset test time value;

[0028] When the duration of the loading state reaches the test time value, the drive coil is de-energized, and the tested three-phase insulation resistance is in a discharge state through the discharge circuit.

[0029] Specifically, the insulation resistance measuring circuit measures the current value corresponding to the phase of the tested three-phase insulation resistance in the loaded state and the discharged state, and determines the state of the tested three-phase insulation resistance based on the current measurement value.

[0030] Preferably, it further includes a display device, the input of which is connected to the output of the insulation resistance measuring unit, for displaying the data parameters detected by the insulation resistance measuring unit.

[0031] Preferably, it further includes a protective housing, which is wrapped around the outside of the control module, the high voltage transformer, the phase switching unit and the insulation resistance measuring unit to isolate voltage leakage.

[0032] In summary, implementing the embodiments of the present invention has the following beneficial effects:

[0033] The insulation resistance tester provided by this invention has a built-in insulation resistance measurement program that can perform measurements according to a specified time sequence and automatically record data. The operation requires no manual intervention and features automatic pressure application and discharge capabilities, eliminating the risk of electric arc injury. It is comprehensive and can complete the testing of the three-phase insulation resistance of power equipment with a single wiring connection, requiring no manual intervention throughout the process; it also boasts a high level of digitalization. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0035] Figure 1 This is a schematic diagram of an insulation resistance tester with three-phase measurement function according to an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of an insulation resistance tester with three-phase measurement function according to an embodiment of the present invention.

[0037] Figure 3 This is an exploded view of an insulation resistance tester with three-phase measurement function according to an embodiment of the present invention.

[0038] Figure 4 This is a schematic diagram of a phase switcher in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0040] like Figure 1 and Figure 2 The diagram shown is a schematic representation of an embodiment of an insulation resistance tester with three-phase measurement function provided by the present invention. In this embodiment, the tester includes:

[0041] The control module contains at least one inverter, which converts the DC power supply signal into a corresponding AC power supply signal and outputs it according to the generated test command.

[0042] The high-voltage transformer converts the AC power supply signal output by the inverter into corresponding high-voltage DC signals and low-voltage DC signals, and outputs the high-voltage DC signals to the phase switcher and returns the low-voltage DC signals to the inverter control circuit corresponding to the inverter.

[0043] A phase switching unit is provided with at least three phase switchers. Each phase switcher is provided with at least one output terminal connected to the three-phase insulation resistance under test, a first input terminal connected to the high-voltage transformer, and a second input terminal connected to the discharge resistor. The phase switching unit connects the output terminal to the input terminal connected to the discharge resistor. When the high-voltage DC signal is received, the output terminal is continuously connected to the second input terminal. The continuous connection is maintained according to a preset test time value.

[0044] An insulation resistance measuring unit is connected to the corresponding phase of the tested three-phase insulation resistance. When the connection between the output terminal and the second input terminal ends, it detects the current measurement value on the corresponding phase of the tested three-phase insulation resistance and determines whether the tested three-phase insulation resistance is normal based on the current measurement value.

[0045] In other words, the phase switchers (including phase A, phase B, and phase C switchers) are high-voltage vacuum relays. Their output terminals are connected to the equipment under test, their upper input terminals are connected to the high-voltage output terminals of the high-voltage transformer, and their lower input terminals are connected to the discharge resistors. The discharge resistors are made of constantan wire, with a discharge resistance value of 5kΩ for phases A, B, and C. One end of the discharge resistor is connected to the phase A, phase B, and phase C switchers, and the other end is connected to the zero potential point of the high-voltage transformer. The high-voltage transformer is an integrated device with a built-in rectifier bridge, voltage divider resistors, protective resistors, and a boost coil. It uses a ferrite core, and the boost coil has 6 primary turns and 8000 secondary turns. The boost coil can generate a 10kV high-voltage AC voltage, which is converted into a 10kV DC voltage through the rectifier bridge. The voltage divider resistor consists of a 50MΩ resistor connected in series with a 25kΩ resistor. The 50MΩ side of the voltage divider resistor is connected to the high-potential side of the rectifier bridge, and the 25kΩ side is connected to the zero-potential side of the rectifier bridge. It can convert the 10kV high-voltage voltage generated by the boost coil into a low voltage of 5V for control module measurement and voltage regulation. The protective resistor is a 1MΩ resistor, which can limit the output current to 10mA to ensure that the output current is within the safe current range for the human body. One end of the protective resistor is connected to the high-potential side of the rectifier bridge, and the other end is connected to the upper input terminal of the A-phase switch, B-phase switch, and C-phase switch through a high-voltage connection line.

[0046] In a specific embodiment, the control module includes: a power supply unit, the inverter, and an inverter control circuit. The inverter control circuit generates a corresponding PWM signal according to the received test command and controls the inverter according to the PWM signal. The power supply unit supplies the inverter with a corresponding DC power supply signal. That is, when the control module starts, it converts the 12V DC power into 20kHz AC power through the DCAC inverter and inputs it to the high-voltage transformer.

[0047] In this embodiment, the high-voltage package includes: a high-voltage transformer, a high-voltage rectifier bridge, and a protection resistor connected in sequence. The high-voltage transformer boosts the input AC power supply signal to obtain a high-voltage AC signal with a corresponding voltage value. The high-voltage rectifier bridge converts the high-voltage AC signal output by the high-voltage transformer into a high-voltage DC signal with a corresponding voltage value. The protection resistor outputs the received high-voltage DC signal from the high-voltage rectifier bridge to the first input terminal of the phase switch to ensure that the output current is within a preset safe current range.

[0048] Specifically, the high-voltage transformer further includes a voltage divider resistor, whose input terminal is connected to the protective resistor, and whose output terminal is connected to both the inverter control circuit and the output voltage measurement circuit within the insulation resistance measurement unit. The voltage divider resistor converts the high-voltage DC signal input at the input terminal into multiple corresponding low-voltage DC signals. One of these low-voltage DC signals powers the inverter control circuit, and another low-voltage DC signal is input as a measurement parameter to the output voltage measurement circuit. In other words, the high-voltage transformer outputs a 10kV high-voltage DC voltage, which is fed back to the inverter control circuit via the voltage divider resistor. The inverter control circuit adjusts the duty cycle of the DC-AC converter based on the output voltage to stabilize the high-voltage transformer output voltage at 10kV. The high-voltage transformer is an integrated device with a built-in rectifier bridge, voltage divider resistors, protective resistors, and a boost coil. It uses a ferrite core, and the boost coil has 6 primary turns and 8000 secondary turns. The boost coil can generate a 10kV high-voltage AC voltage, which is converted into a 10kV DC voltage through the rectifier bridge. The voltage divider resistor consists of a 50MΩ resistor connected in series with a 25kΩ resistor. The 50MΩ side of the voltage divider resistor is connected to the high-potential side of the rectifier bridge, and the 25kΩ side is connected to the zero-potential side of the rectifier bridge. It can convert the 10kV high-voltage voltage generated by the boost coil into a low voltage of 5V for control module measurement and voltage regulation. The protective resistor is a 1MΩ resistor, which can limit the output current to 10mA to ensure that the output current is within the safe current range for the human body. One end of the protective resistor is connected to the high-potential side of the rectifier bridge, and the other end is connected to the upper input terminal of the A-phase switch, B-phase switch, and C-phase switch through a high-voltage connection line.

[0049] In this embodiment, the phase switcher further includes a drive coil and a switching electrode. The drive coil is wound around the outside of the switching electrode, and the drive coil can drive the switching electrode to move according to the input DC voltage. One end of the switching electrode is connected to the output terminal, and the other end of the switching electrode is disposed between the first input terminal and the second input terminal. When there is no voltage in the drive coil, the switching electrode is connected to the second input terminal; when there is voltage in the drive coil, the switching electrode is connected to the first input terminal.

[0050] Specifically, the phase switcher is used to, after the drive coil inside is energized, apply the high-voltage DC signal through the switching electrode and the second input terminal connected to the switching electrode to the corresponding phase of the tested three-phase insulation resistance, and maintain the corresponding loading state according to a preset test time value; when the duration of the loading state reaches the test time value, the drive coil is de-energized, and the tested three-phase insulation resistance is in a discharge state through the discharge circuit; wherein, the insulation resistance measuring circuit measures the current measurement value corresponding to the phase of the tested three-phase insulation resistance in the loading state and the discharge state, and determines the state of the tested three-phase insulation resistance based on the current measurement value. That is, the switching device is a finished product, internally vacuumed, and can withstand a DC voltage of 20kV. When there is no voltage in the drive coil, the switching electrode connects the output terminal to the lower input terminal under the action of elasticity, at which time the switching device connects the output terminal to the ground potential. When a 24V DC voltage is applied to the drive coil, the switching electrode moves upward under the action of the magnetic field and connects to the upper input terminal. At this time, the switching device connects the output terminal to the output terminal of the high voltage transformer.

[0051] In this embodiment, the other end of the discharge resistor is connected to the zero-point phase located inside the high-voltage transformer. When there is voltage in the drive coil, the corresponding phase of the tested three-phase insulation resistance, the output terminal, the switching electrode, the first input terminal, the discharge resistor, and the zero-point phase are connected to form a discharge circuit for discharging the tested three-phase insulation resistance. That is, the insulation resistance tester disconnects the coil of the phase switcher, and the high-voltage side of the tested equipment is connected to the discharge resistor and the grounding terminal through the output terminal of the phase switch, forming a discharge circuit. The charge accumulated on the phase is completely released, and this state is maintained for 20 seconds to ensure that the phase charge is completely released.

[0052] In this embodiment, the insulation resistance measurement unit includes at least three insulation resistance measurement circuits and the output voltage measurement circuit. The input terminals of the insulation resistance measurement circuits are respectively connected to the corresponding phases of the tested three-phase insulation resistance and the output terminal of the output voltage measurement circuit. The input terminal of the output voltage measurement circuit is connected to the output terminal of the voltage divider resistor.

[0053] Specifically, it also includes a display device, whose input terminal is connected to the output terminal of the insulation resistance measuring unit to display the data parameters detected by the insulation resistance measuring unit; and a protective housing, which surrounds the control module, the high-voltage transformer, the phase switching unit, and the insulation resistance measuring unit to isolate voltage leakage. That is, the display screen is a component of the control module, its function is human-computer interaction, it is a finished product, and it has touch control and display functions. The housing is made of ABS plastic through milling to protect the internal electronic components and also to isolate high voltage, preventing leakage of high voltage from inside the instrument. The grounding terminal is a finished product, with its upper end connected to the grounding wire of the device under test and its lower end connected to the discharge resistor.

[0054] In one specific embodiment, such as Figure 3As shown, the tester includes: 1. Lower housing; 2. Upper housing; 3. Grounding terminal; 4. Control module display screen; 5. Charging port; 6. Power switch; 7. A-phase switcher; 8. B-phase switcher; 9. C-phase switcher; 10. High-voltage transformer; 11. Control module; 12. High-voltage connection line; 13. Discharge resistor; 14. Switcher support frame. The lower and upper housings are made of milled ABS plastic to protect internal electronic components and isolate high voltage, preventing leakage of internal high voltage. The grounding terminal is a finished product; its upper end connects to the grounding wire of the device under test, and its lower end connects to the discharge resistor. The control module display screen is a component of the control module, providing human-machine interaction; it is a finished product with touch control and display functions. The charging port is used to charge the lithium battery built into the control module. The power switch is used to switch the device on and off. The A-phase switcher, B-phase switcher, and C-phase switcher are high-voltage vacuum relays; their output terminals are connected to the device under test, their upper input terminals are connected to the high-voltage output terminal of the high-voltage transformer, and their lower input terminals are connected to the discharge resistor. The high-voltage connection cable is a silicone-shielded cable, capable of withstanding 20kV DC voltage. The discharge resistors are made of constantan wire, with a resistance value of 5kΩ for phases A, B, and C. One end of the discharge resistor is connected to the phase A switch, phase B switch, and phase C switch, respectively, and the other end is connected to the zero-potential point of the high-voltage transformer. The switch support frame is milled from ABS and is used to connect and fix the switch. The high-voltage transformer is an integrated device with a built-in rectifier bridge, voltage divider resistors, protective resistors, and a boost coil. It uses a ferrite core, and the boost coil has 6 primary turns and 8000 secondary turns. The boost coil can generate a 10kV high-voltage AC voltage, which is converted into a 10kV DC voltage through the rectifier bridge. The voltage divider resistor consists of a 50MΩ resistor connected in series with a 25kΩ resistor. The 50MΩ side of the voltage divider resistor is connected to the high-potential side of the rectifier bridge, and the 25kΩ side is connected to the zero-potential side of the rectifier bridge. It can convert the 10kV high-voltage voltage generated by the boost coil into a low voltage of 5V for control module measurement and voltage regulation. The protective resistor is a 1MΩ resistor, which can limit the output current to 10mA to ensure that the output current is within the safe current range for the human body. One end of the protective resistor is connected to the high-potential side of the rectifier bridge, and the other end is connected to the upper input terminal of the A-phase switch, B-phase switch, and C-phase switch through a high-voltage connection line.

[0055] Specifically, such as Figure 4As shown, 101 is the output terminal, 201 is the upper input terminal, 301 is the lower input terminal, 401 is the switching electrode, and 501 is the drive coil. The switching device is internally evacuated and can withstand a 20kV DC voltage. When there is no voltage in the drive coil, the switching electrode, under the action of its elasticity, connects the output terminal to the lower input terminal. At this time, the switching device connects the output terminal to ground potential. When a 24V DC voltage is applied to the drive coil, the switching electrode moves upward under the action of the magnetic field and connects to the upper input terminal. At this time, the switching device connects the output terminal to the high-voltage transformer output terminal.

[0056] In this embodiment, the working method is as follows: the operator connects the output terminals of the A-phase switch, B-phase switch, and C-phase switch to the A-phase, B-phase, and C-phase high-voltage sides of the device under test, and connects the grounding terminal to the grounding wire of the device under test.

[0057] Turn on the power switch of the insulation resistance tester and start the tester via the touch display screen; it will then enter fully automatic measurement mode.

[0058] 1. When the control module starts, it converts 12V DC power into 20kHz AC power through the DCAC inverter and inputs it into the high-voltage transformer. The high-voltage transformer outputs a 10kV high-voltage DC voltage. The output voltage is fed back to the inverter control circuit through the voltage divider resistor. The inverter control circuit adjusts the duty cycle of the DCAC converter according to the output voltage to stabilize the output voltage of the high-voltage transformer at 10kV.

[0059] 2. The insulation resistance tester is connected to the coil of the A-phase switch, applying 10kV high voltage to phase A of the equipment under test through the output terminal of the A-phase switch. At this time, the high voltage sides of phases B and C of the equipment under test are connected to the discharge resistor and grounding terminal through the output terminal of the B-phase switch, maintaining a grounded state. This state is maintained for 60 seconds. The instrument calculates the insulation resistance and absorption ratio of phase A of the equipment under test by reading the leakage current of phase A.

[0060] 3. Disconnect the coil of the A-phase switch of the insulation resistance tester. Connect the high-voltage side of the A-phase of the tested equipment to the discharge resistor and grounding terminal through the output terminal of the A-phase switch to form a discharge circuit, so as to release the charge accumulated on the A-phase. Maintain this state for 20 seconds to ensure that the charge on the A-phase is completely released.

[0061] 4. Repeat steps 2 and 3 to connect the coils of phase B and phase C switch respectively, so as to measure the insulation resistance and absorption ratio of phase B and phase C of the tested equipment.

[0062] 5. When the insulation resistance tester control module disconnects the DCAC inverter, the high-voltage transformer output voltage drops to zero.

[0063] 6. The insulation resistance tester displays the insulation resistance and absorption ratio values ​​of phase A, phase B, and phase C on its screen.

[0064] 7. The staff records the values, turns off the insulation resistance tester, disconnects the test wiring, and completes the measurement.

[0065] In summary, implementing the embodiments of the present invention has the following beneficial effects:

[0066] The insulation resistance tester provided by this invention has a built-in insulation resistance measurement program that can perform measurements according to a specified time sequence and automatically record data. The operation requires no manual intervention and features automatic pressure application and discharge capabilities, eliminating the risk of electric arc injury. It is comprehensive and can complete the testing of the three-phase insulation resistance of power equipment with a single wiring connection, requiring no manual intervention throughout the process; it also boasts a high level of digitalization.

[0067] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. An insulation resistance tester with three-phase measurement functions, characterized in that, include: The control module contains at least one inverter, which converts the DC power supply signal into a corresponding AC power supply signal and outputs it according to the generated test command. The high-voltage transformer converts the AC power supply signal output by the inverter into corresponding high-voltage DC signals and low-voltage DC signals, and outputs the high-voltage DC signals to the phase switcher and returns the low-voltage DC signals to the inverter control circuit corresponding to the inverter. A phase switching unit is provided with at least three phase switchers. Each phase switcher has at least one output terminal connected to the three-phase insulation resistance of the test object, a first input terminal connected to the high-voltage transformer, and a second input terminal connected to the discharge resistor. The phase switching unit connects the output terminal to the second input terminal connected to the discharge resistor. When the high-voltage DC signal is received, the output terminal is continuously connected to the first input terminal. The continuous connection is maintained according to a preset test time value. The phase switcher also includes a drive coil and a switching electrode. The drive coil is wound around the outside of the switching electrode and can drive the switching electrode to move according to the input DC voltage. One end of the switching electrode is connected to the output terminal, and the other end of the switching electrode is disposed between the first input terminal and the second input terminal. When there is no voltage in the drive coil, the switching electrode is connected to the second input terminal. When there is voltage in the drive coil, the switching electrode is connected to the first input terminal. An insulation resistance measuring unit is connected to the corresponding phase of the tested three-phase insulation resistance and detects the current measurement value on the corresponding phase of the tested three-phase insulation resistance, and determines whether the tested three-phase insulation resistance is normal based on the current measurement value; the insulation resistance measuring unit includes at least three insulation resistance measuring circuits and an output voltage measuring circuit, the input terminals of the insulation resistance measuring circuits are respectively connected to the corresponding phase of the tested three-phase insulation resistance and the output terminal of the output voltage measuring circuit, and the input terminal of the output voltage measuring circuit is connected to the output terminal of the voltage divider resistor; The phase switcher is specifically used to, after the drive coil inside is energized, apply the high-voltage DC signal through the switching electrode and the first input terminal connected to the switching electrode to the corresponding phase of the tested three-phase insulation resistance, and maintain the corresponding loading state according to a preset test time value; when the duration of the loading state reaches the test time value, the drive coil is de-energized, and the tested three-phase insulation resistance is in a discharge state through a discharge circuit; wherein, the insulation resistance measuring circuit measures the current measurement value corresponding to the phase of the tested three-phase insulation resistance in the loading state and the discharge state, and determines the state of the tested three-phase insulation resistance based on the current measurement value.

2. The insulation resistance tester with three-phase measurement function as described in claim 1, characterized in that, The control module includes: a power supply unit, the inverter, and an inverter control circuit. The inverter control circuit generates a corresponding PWM signal according to the received test command, and controls the inverter according to the PWM signal; The power supply unit supplies the corresponding DC power supply signal to the inverter.

3. The insulation resistance tester with three-phase measurement function as described in claim 2, characterized in that, The high-voltage package includes: a high-voltage transformer, a high-voltage rectifier bridge, and a protective resistor connected in sequence. The high-voltage transformer boosts the input AC power supply signal to obtain a high-voltage AC signal with the corresponding voltage value. The high-voltage rectifier bridge converts the high-voltage AC signal output by the high-voltage transformer into a high-voltage DC signal with a corresponding voltage value. The protection resistor receives the high-voltage DC signal from the high-voltage rectifier bridge and outputs it to the first input terminal of the phase switch to ensure that the output current is within a preset safe current range.

4. The insulation resistance tester with three-phase measurement function as described in claim 3, characterized in that, The high-voltage transformer further includes: a voltage divider resistor, the input of which is connected to the protective resistor, and the output of which is connected to both the inverter control circuit and the output voltage measurement circuit within the insulation resistance measurement unit. The voltage divider resistor converts the high-voltage DC signal input at the input terminal into multiple corresponding low-voltage DC signals. One of the low-voltage DC signals powers the inverter control circuit, and another low-voltage DC signal is input as a measurement parameter to the output voltage measurement circuit.

5. The insulation resistance tester with three-phase measurement function as described in claim 4, characterized in that, The other end of the discharge resistor is connected to the zero-point phase set inside the high-voltage transformer. When there is no voltage in the drive coil, the corresponding phase of the tested three-phase insulation resistance, the output terminal, the switching electrode, the second input terminal, the discharge resistor, and the zero-point phase are connected to form a discharge circuit for discharging the tested three-phase insulation resistance.

6. The insulation resistance tester with three-phase measurement function as described in claim 1, characterized in that, It also includes a display device, the input of which is connected to the output of the insulation resistance measuring unit, for displaying the data parameters detected by the insulation resistance measuring unit.

7. The insulation resistance tester with three-phase measurement function as described in claim 6, characterized in that, It also includes a protective housing, which is wrapped around the outside of the control module, the high voltage transformer, the phase switching unit and the insulation resistance measuring unit to prevent voltage leakage.

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