Switch cabinet insulation resistance measuring system based on direct current generator

Abstract

The invention relates to the technical field of high-voltage electrical equipment insulation resistance measurement, in particular to a switch cabinet insulation resistance measurement system based on a direct current generator, which comprises a state acquisition module for automatically acquiring a switch position state signal and a cable side electrification state signal and transmitting the signals to a locking control module; the locking control module performs logic judgment on the input signal, and outputs a measurement permission instruction to the measurement execution module when a safety condition is met; the measurement execution module starts a direct-current generator to generate direct-current high voltage, constructs an insulation resistance measurement loop and calculates an insulation resistance value; and the result display module displays the measurement result and verifies the integrity of the loop through a voltmeter arranged on the cable side. According to the invention, remote insulation measurement is realized through a modular architecture, and the safety risk caused by manual entering into a high-voltage interval is effectively eliminated.

Description

Technical Field

[0001] This invention relates to the field of insulation resistance measurement technology for high-voltage electrical equipment, and in particular to a switchgear insulation resistance measurement system based on a DC generator. Background Technology

[0002] The insulation condition of electrical equipment not only affects its normal operation but also determines its lifespan. For in-service electrical equipment, it is essential to monitor its insulation condition promptly: insulation resistance parameters must be measured for motors, transformers, cables, and busbars after maintenance and before commissioning after long-term shutdowns, including phase-to-phase and phase-to-ground insulation resistance.

[0003] There are two main types of insulation resistance meters used on-site: a DC motor-driven hand-cranked insulation resistance meter and a DC generator-driven insulation resistance meter. The insulation resistance measurement procedure is as follows: First, de-energize the electrical equipment under test: pull the switch and disconnect all power supplies associated with the equipment. Second, verify the integrity of the insulation resistance meter: observe whether the measured values ​​are normal under open and short circuit conditions at the meter terminals. Third, connect the insulation resistance meter to the electrical equipment under test and measure the insulation resistance to ground and between phases. Finally, disconnect the insulation resistance meter from the electrical equipment under test.

[0004] Existing switchgear insulation resistance measurement technology suffers from the following technical challenges: In substations or distribution rooms with densely packed high-voltage switchgear, periodic insulation verification of multiple electrical bays along a busbar requires operators to carry portable insulation resistance meters to measure each de-energized bay individually. Since adjacent bays are often energized and the cabinet layout is compact, manual entry into the bays for wiring, operation, and disconnection carries inherent safety risks. For example, operators may mistakenly enter adjacent energized bays due to visual errors or unclear markings, directly contacting high-voltage live parts and causing electric shock. When performing wiring operations in confined spaces, improper control of hand tools or body parts may exceed safe distances, accidentally touching energized busbars or bushings, leading to arcing. After measurement, in the rush, test leads of the insulation resistance meter may be left on the equipment terminals. When the bay is re-energized, the leftover wires can cause phase-to-phase short circuits or grounding faults, seriously threatening power grid safety. This existing method, relying on close-range manual operation, cannot fundamentally eliminate the multiple safety hazards caused by human factors and the complexity of the equipment environment. Summary of the Invention

[0005] The purpose of this invention is to provide a switchgear insulation resistance measurement system based on a DC generator, in order to solve the technical problems caused by the requirement of operators to enter the high-voltage switchgear compartment for manual wiring and close-range operation, which may lead to electric shock and short circuit risks to personnel and equipment due to accidental entry into live compartments, accidental contact with live parts, and leaving foreign objects.

[0006] To solve the above-mentioned technical problems, the specific contents of the present invention are as follows: This invention provides a switchgear insulation resistance measurement system based on a DC generator, comprising a status acquisition module, an interlocking control module, a measurement execution module, and a result display module; The status acquisition module outputs a switch position status signal and a cable side energization status signal to the interlocking control module. The interlocking control module receives the switch position status signal and the cable side energized status signal, performs logical judgment on the switch position status signal and the cable side energized status signal, and outputs a measurement permission command to the measurement execution module when the judgment condition is met. The measurement execution module receives the measurement permission command, and when the measurement permission command is valid and the insulation resistance measurement activation switch is closed, it starts the DC generator to generate a DC high voltage, and simultaneously controls the phase selection contact to close to construct an insulation resistance measurement circuit. The insulation resistance value is calculated by the current generated in the insulation resistance measurement circuit by the DC high voltage, and the insulation resistance value is sent to the result display module. The result display module receives and displays the insulation resistance value. The result display module also includes a voltmeter installed on the side of the cable to be tested. The voltmeter is used to monitor the voltage across the insulation resistance measurement circuit to verify the circuit integrity.

[0007] Furthermore, in the switchgear insulation resistance measurement system based on a DC generator described in this invention, the status acquisition module includes a switch position detection unit and a live status detection unit; The switch position detection unit is configured to collect the position information of the switch trolley through a mechanical limit contact linked to the switch operating mechanism, and output a first electrical signal representing the safe position when the switch trolley is in the test position or the moved-out position. The live state detection unit is configured to monitor the cable-side voltage through a normally closed contact connected to the cable-side live display, and output a second electrical signal indicating no voltage when there is no voltage on the cable side. The first electrical signal output by the switch position detection unit and the second electrical signal output by the energized state detection unit are photoelectrically isolated and then input to the interlocking control module as the switch position status signal and the cable-side energized state signal.

[0008] Furthermore, in the switchgear insulation resistance measurement system based on a DC generator described in this invention, the interlocking control module includes a signal processing unit and a logic judgment unit; The signal processing unit is configured to perform filtering and de-jitter processing on the received first electrical signal and second electrical signal, and output the filtered and de-jittered first electrical signal and second electrical signal. The logic judgment unit is configured to perform a logical AND operation on the first electrical signal and the second electrical signal after filtering and de-jittering, and drive the safety relay to engage when both the first electrical signal and the second electrical signal are true. The normally open contact of the safety relay is connected in series in the control circuit of the measurement execution module, and the closing action of the normally open contact constitutes the measurement permission command.

[0009] Furthermore, in the switchgear insulation resistance measurement system based on a DC generator described in this invention, the measurement execution module includes a DC generation unit and a loop construction unit; The DC generating unit is configured to start after the control circuit is turned on, and process the input power supply into a stable DC high voltage of a set voltage level. The circuit construction unit is configured to receive the stable DC high voltage output by the DC generator unit after the insulation resistance measurement activation switch is closed, and control the phase selection relay to operate in order to construct an insulation resistance measurement circuit to the device under test. The DC generating unit applies the stable DC high voltage to the insulation resistance measurement circuit and calculates the insulation resistance value by measuring the current in the insulation resistance measurement circuit.

[0010] Furthermore, in the switchgear insulation resistance measurement system based on a DC generator described in this invention, the result display module includes a voltage measurement unit and a status indication unit; The voltage measurement unit is configured to acquire a voltage sampling signal from the insulation resistance measurement circuit, and output the measured voltage value to the status indication unit after voltage division and conditioning. The status indication unit is configured to receive the insulation resistance value and the measured voltage value, and to display the insulation resistance value and the measured voltage value; The status indication unit is configured to compare the measured voltage value with a preset threshold, and trigger an alarm when the measured voltage value is lower than the preset threshold.

[0011] Furthermore, in the switchgear insulation resistance measurement system based on a DC generator described in this invention, the status indication unit includes a comparator circuit and an alarm drive circuit; The first input terminal of the comparator circuit receives the measured voltage value, and the second input terminal receives the preset threshold. The output of the comparator circuit is connected to the input of the alarm drive circuit; The output of the alarm drive circuit is connected to the audible and visual alarm. When the measured voltage value is lower than the preset threshold, the comparator circuit outputs a level transition signal to the alarm driving circuit, and the alarm driving circuit responds to the level transition signal to drive the audible and visual alarm to issue an alarm.

[0012] Furthermore, in the switchgear insulation resistance measurement system based on a DC generator described in this invention, the contacts of the insulation resistance measurement activation switch and the normally open contacts of the safety relay are connected in series in the coil circuit of the phase selection relay. The on / off state of the phase selection relay is controlled by the series connection of the contacts of the insulation resistance measurement switch and the normally open contacts of the safety relay.

[0013] Furthermore, in the switchgear insulation resistance measurement system based on a DC generator described in this invention, the status indication unit includes a verification logic circuit, and the verification logic circuit pre-stores reference data characterizing the normal correspondence between the insulation resistance value and the measured voltage value. The verification logic circuit receives the insulation resistance value and the measured voltage value, and performs matching calculations between the insulation resistance value and the measured voltage value and the reference data; When the matching calculation result exceeds the preset tolerance range, the verification logic circuit outputs an abnormal signal to the alarm driving circuit to trigger an alarm.

[0014] Furthermore, the switchgear insulation resistance measurement system based on a DC generator described in this invention also includes: The DC generator, the insulation resistance measurement switch, and the result display module are all installed in one measurement cabinet. The measuring cabinet is connected to the interlocking control module via a set of prefabricated cables, and is connected to the cable side of each switch cabinet on the bus via multiple branch cables; The DC generator inside the measurement cabinet provides the DC high voltage required for insulation resistance measurement to each switch cabinet through the branch cable, thereby completing the centralized measurement of the insulation status of the bus system.

[0015] Furthermore, in the switchgear insulation resistance measurement system based on a DC generator described in this invention, the insulation resistance measurement activation switch is a three-position selector switch, which includes an active position, an isolating position, and a connected position. When the three-position selector switch is in the active position, the control circuit of the measurement execution module is activated; When the three-position selector switch is in the isolation position, the connection with the measurement execution module is disconnected. When the three-position changeover switch is in the grounded position, the cable side of the switch cabinet is grounded.

[0016] Beneficial effects of this invention; This invention automatically monitors the switch position status and cable energization status through a status acquisition module, replacing the existing manual on-site confirmation method and effectively eliminating the risk of accidentally entering energized areas. The interlocking control module adopts a hardware logic decision mechanism, only outputting a measurement permission command when both safety conditions are met simultaneously, eliminating the possibility of misoperation at the circuit level. The measurement execution module realizes remote loop construction through a prefabricated cable network, allowing operators to complete insulation measurements without approaching high-voltage equipment, significantly improving operational safety. The result display module's voltmeter monitors loop integrity in real time, and combined with the verification logic circuit, cross-validates the measurement data, effectively identifying wiring anomalies and issuing warnings to prevent short-circuit faults caused by foreign objects. The centralized measurement architecture allows a single system to serve all switchgear on the entire busbar, greatly improving operation and maintenance efficiency, while the mechanical interlocking design of the three-position changeover switch further enhances operational safety. Attached Figure Description

[0017] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the system architecture of the switchgear insulation resistance measurement system based on a DC generator according to the present invention. Detailed Implementation

[0019] To make the technical solution of the present invention clearer, the present invention will be clearly and completely described below with reference to specific embodiments and corresponding drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The present invention provided by various embodiments will be described in detail below with reference to the accompanying drawings. To better understand the purpose of the present invention, the present invention will be described in further detail below.

[0020] Please see Figure 1 The present invention provides a switchgear insulation resistance measurement system based on a DC generator, comprising a status acquisition module, a lockout control module, a measurement execution module and a result display module; The status acquisition module outputs a switch position status signal and a cable side energization status signal to the interlocking control module. The interlocking control module receives the switch position status signal and the cable side energized status signal, performs logical judgment on the switch position status signal and the cable side energized status signal, and outputs a measurement permission command to the measurement execution module when the judgment condition is met. The measurement execution module receives the measurement permission command, and when the measurement permission command is valid and the insulation resistance measurement activation switch is closed, it starts the DC generator to generate a DC high voltage, and simultaneously controls the phase selection contact to close to construct an insulation resistance measurement circuit. The insulation resistance value is calculated by the current generated in the insulation resistance measurement circuit by the DC high voltage, and the insulation resistance value is sent to the result display module. The result display module receives and displays the insulation resistance value. The result display module also includes a voltmeter installed on the side of the cable to be tested. The voltmeter is used to monitor the voltage across the insulation resistance measurement circuit to verify the circuit integrity.

[0021] The status acquisition module acquires the operating status of the switchgear in real time via physical connection. The switch position detection unit uses mechanical limit contacts linked to the switch operating mechanism. When the switch trolley is operated to the test position or completely moved out of the bay, the mechanical transmission mechanism drives the high-insulation auxiliary contact to close, generating an electrical signal representing the safe position. The live-line status detection unit is directly connected to the normally closed contact of the cable-side live-line indicator. This indicator detects the electric field strength based on the capacitive voltage division principle, and the contact automatically opens when voltage is present on the cable side. Both sets of detection units safely transmit the high-voltage side signal to the low-voltage control circuit through opto-isolators.

[0022] The interlocking control module performs safety logic decisions on the acquired status signals. The signal processing unit first filters and debouncing the raw electrical signal to eliminate interference pulses caused by contact jitter. The processed signal is then sent to the logic judgment unit for double interlocking verification: the logic AND operation circuit will only output a valid command if it simultaneously receives the "test / isolation position" signal from the switch position detection unit and the "no voltage" signal from the energized state detection unit. This command drives the safety relay to engage, and its normally open contact is connected in series in the control circuit of the measurement loop, forming a hardware-level interlocking mechanism.

[0023] After obtaining safety clearance, the measurement execution module initiates the insulation resistance measurement process. The DC generation unit uses insulated-gate bipolar transistor (IGBT) inverter technology to convert the power frequency AC current into a stable and adjustable DC high voltage. The phase selection relay group in the circuit construction unit is controlled by the activation switch, sequentially connecting the corresponding circuits according to the needs of phase-to-phase or phase-to-ground measurement. When the operator remotely closes the insulation resistance measurement activation switch, the DC high voltage is applied to the insulation surface of the device under test via the measurement cable. The measurement circuit calculates the insulation resistance value based on Ohm's law by detecting the micro-current flowing through the circuit.

[0024] The results display module provides visualization and verification functions for measurement data. A high-impedance digital voltmeter is connected to the measurement circuit via a precision resistance divider to display the actual voltage value applied across the insulation material in real time. The status indicator unit synchronously displays the insulation resistance value calculated by the DC generator unit. When an abnormal voltage drop in the circuit is detected, the system automatically triggers an audible and visual alarm and locks the DC output. This design can verify the integrity of the measurement circuit and identify measurement errors caused by cable short circuits or poor contact.

[0025] The system achieves closed-loop control of the measurement process through a modular architecture. Real-time monitoring data from the status acquisition module serves as input for interlocking decisions, while the output commands from the interlocking control module determine the activation permissions of the measurement execution module. The execution results are ultimately fed back to the operator through the display module. All modules communicate via standard interfaces, and the measurement cabinet is connected to the field switchgear via pre-fabricated cables, forming a complete remote insulation measurement network. This design allows operators to complete all measurement operations outside the switchgear compartment, fundamentally eliminating the safety risks of accidentally entering live compartments or touching live parts.

[0026] The implementation of the status acquisition module involves two key detection units. The switch position detection unit employs a mechanical linkage mechanism. When the operator moves the switch trolley to the test position or pulls it out of the interval, the mechanical limit contacts rotate with the drive shaft, changing their on / off state and generating a switching signal representing the safe position. The live-line status detection unit directly acquires the status of the secondary circuit contacts of the live-line indicator. This indicator senses the electric field through the principle of capacitive voltage division; when there is voltage on the cable side, the internal relay activates and opens the normally closed contact. The two sets of detection signals are electrically isolated through an optocoupler, effectively preventing high voltage from entering the low-voltage control system.

[0027] The interlocking control module employs a two-stage processing mechanism. The signal processing unit uses an RC filter circuit to eliminate contact bounce interference and prevent false judgments. The processed clean signal is sent to a judgment unit composed of relay logic or solid-state logic. The drive circuit will only activate the safety relay when both conditions are met simultaneously: "the switch is in the safe position" and "there is no voltage on the cable side." The normally open contact of this relay is directly connected in series in the power supply circuit of the measurement and execution module, forming a hard-wired interlock.

[0028] The DC generation unit of the measurement execution module adopts high-frequency inverter technology. It first rectifies and filters the power frequency AC, then inverts it into high-frequency AC through an insulated gate bipolar transistor. After being stepped up by a high-frequency transformer, it is rectified to obtain a stable DC high voltage. The circuit construction unit realizes the measurement mode switching through a phase selection relay group. When it is necessary to measure the insulation of phase A to ground, the corresponding relay is energized to lead the high voltage to the phase A winding, and the other phases are grounded through the relay contacts to form a circuit.

[0029] The voltage measurement unit of the results display module employs a high input impedance design, converting kilovolt-level high voltage into an acquireable low-voltage signal through a precision resistor voltage divider network. The status indicator unit is equipped with dual display windows, simultaneously showing the insulation resistance value and the measured voltage value. An alarm circuit is activated when an abnormal voltage drop is detected. This design can both verify the continuity of the measurement loop and identify insulation degradation.

[0030] To address the need for voltage anomaly detection, the system incorporates an independent comparison alarm circuit. The comparator chip continuously compares the actual measured voltage with a reference voltage value. When the voltage falls below a set threshold, it outputs a switching signal to trigger the alarm drive circuit. The drive circuit uses a Darlington transistor to amplify the current, directly driving the audible and visual alarm to issue a warning.

[0031] The phase selection relay control circuit employs a double interlock design. The activation switch contact and the safety relay contact are connected in series in the relay coil circuit; the phase selection circuit is only activated when both contacts are closed simultaneously. This design prevents the phase selection relay from being accidentally activated when safety conditions are not met.

[0032] The system also includes a data verification mechanism. The verification logic circuit stores a standard insulation resistance-voltage curve and compares the measured data with the standard curve in real time. When an abnormal deviation is detected, it is determined to be a fault in the measurement circuit and an early warning is activated to prevent measurement errors caused by poor wiring.

[0033] The measuring cabinet adopts a centralized layout, integrating the DC generator, switching devices, and display instruments within the protective cabinet. The cabinet is connected to each compartment of the switch room via prefabricated cables, allowing operators to directly operate the switching devices and read data from the cabinet door, completely avoiding entry into the high-voltage compartments.

[0034] The three-position switch has a clear mechanical positioning function. When turned to the active position, the measurement circuit is connected; when turned to the isolating position, the connection is physically disconnected; and when turned to the grounding position, the cable side is grounded through mechanical interlocking. Each position has a clear positioning feel and mechanical self-holding characteristics.

[0035] This invention's system achieves functional separation through modular design, with signals transmitted between modules via standard interfaces. The data flow begins with real-time monitoring by the status acquisition module, undergoes safety verification by the interlocking control module, triggers pressure measurement by the measurement execution module, and finally is presented by the result display module. This layered processing mechanism ensures both measurement accuracy and inherent safety.

[0036] In distribution rooms with densely packed high-voltage switchgear, when operators need to measure the insulation resistance of multiple bays along a busbar, existing methods require personnel to enter each bay to perform wiring operations, posing safety risks such as accidentally entering live bays, accidentally touching live parts, and leaving foreign objects behind. This system achieves remote insulation measurement through modular design, fundamentally eliminating the safety hazards caused by direct manual operation.

[0037] During system operation, the status acquisition module continuously monitors the switchgear's operating status. The switch position detection unit acquires the switch trolley position via a mechanical linkage mechanism. When the trolley is in the test position or the moved-out position, the mechanical limit contact closes, generating a first electrical signal. The energized status detection unit is connected to the normally closed contact of the cable-side energized indicator. When there is no voltage on the cable side, the contact remains closed, generating a second electrical signal. The two sets of signals are electrically isolated by an opto-isolator before being transmitted to the interlocking control module.

[0038] The interlocking control module performs safety logic checks on the input signal. The signal processing unit uses an RC filter circuit to debounce the input signal, eliminating interference pulses caused by contact jitter. The processed signal is sent to the logic judgment unit, which implements an AND operation function through a relay logic circuit. The safety relay will only be activated when both the first and second electrical signals are at a valid level. The normally open contact of the safety relay is connected in series in the control circuit of the measurement execution module, forming a hardware-level interlocking mechanism.

[0039] After obtaining safety clearance, the measurement execution module initiates the insulation resistance measurement process. The DC generation unit uses IGBT inverter technology to convert the power frequency AC current into a stable DC high voltage of the set voltage level. The phase selection relay group in the circuit construction unit is controlled by the insulation resistance measurement activation switch. When the activation switch is closed, the phase selection relays connect the corresponding circuits in a preset sequence. The DC high voltage is applied to the device under test through the measurement cable, and the measurement circuit calculates the insulation resistance value based on Ohm's law by detecting the circuit current value.

[0040] The results display module provides display and verification functions for measurement data. The voltage measurement unit acquires the voltage of the measurement circuit through a precision resistor divider, converting the high-voltage signal into a measurable low-voltage signal. The status indication unit is equipped with a digital display screen that simultaneously displays the insulation resistance value and the measured voltage value. When the measured voltage value is lower than a preset threshold, the comparator circuit outputs a level transition signal, triggering an audible and visual alarm to issue a warning.

[0041] The system also includes a data verification mechanism. The verification logic circuit stores the corresponding curves of standard insulation resistance and voltage, and compares the deviation of the measured data with the standard value in real time. When an abnormal deviation is detected, it is judged as a fault in the measurement circuit and an early warning is activated. The phase selection relay control circuit adopts a double interlock design, with the activation switch contact and the safety relay contact connected in series in the relay coil circuit to ensure that the phase selection circuit can only be activated when the safety conditions are met.

[0042] The measurement cabinet adopts a centralized layout, integrating the DC generator, switching device, and display instruments within a protective cabinet. The cabinet is connected to each switch cabinet via pre-fabricated cables, allowing operators to complete all operations directly from the cabinet door. The insulation resistance measurement switching device is a three-position selector switch with clearly defined positions: active, isolating, and grounded. A mechanical positioning mechanism ensures accurate operation.

[0043] This invention's system achieves closed-loop control of the measurement process through a modular architecture. The data flow begins with status acquisition, followed by interlocking control to determine safety conditions, triggering the measurement execution module, and finally, the result display module provides feedback on the measurement status. All modules communicate via standard interfaces, forming a complete remote insulation measurement system. This design allows operators to safely complete insulation measurements outside the switchgear compartment, effectively addressing the safety risks inherent in existing measurement methods.

[0044] This invention fundamentally solves the safety hazards of existing insulation resistance measurement methods through modular system design and remote control mechanism. The status acquisition module automatically acquires switch position status signals and cable-side energization status signals via mechanical limit contacts and energized display contacts, replacing manual on-site verification and eliminating the possibility of accidental entry into energized areas. The interlocking control module uses hardware logic circuits to double-verify the acquired signals, only outputting a measurement permission command when the switch is in a safe position and there is no voltage on the cable side. This hard-wired interlocking mechanism effectively prevents the risk of accidental closing of the energized circuit due to misoperation.

[0045] The measurement execution module enables remote circuit construction through a prefabricated cable network and phase selection relays. Operators only need to operate the insulation resistance measurement activation switch on the measurement cabinet to complete all wiring work, completely avoiding the opportunity for personnel to come into contact with high-voltage live parts. The result display module, with a voltmeter installed on the cable side of the tested interval, can monitor the circuit integrity in real time. Once an abnormal voltage is detected, an alarm is immediately triggered, effectively identifying potential short circuit hazards caused by poor wiring or foreign objects. The system integrates the DC generator, activation switch, and display instruments in the measurement cabinet, connecting to each switch cabinet through standard interfaces to form a complete remote measurement system.

[0046] This modular architecture enables closed-loop control of the measurement process. The data flow begins with status acquisition, followed by interlocking control to determine safety conditions, triggering the measurement execution module, and finally, the measurement status is fed back through the result display module. During this invention, operators do not need to enter the switchgear compartment; they can safely complete insulation measurements from a distance away from the high-voltage equipment, completely eliminating the safety risks associated with manual wiring and close-range operation in existing methods.

Claims

1. A switchgear insulation resistance measurement system based on a DC generator, characterized in that, It includes a status acquisition module, an interlock control module, a measurement execution module, and a result display module; The status acquisition module outputs a switch position status signal and a cable side energization status signal to the interlocking control module. The interlocking control module receives the switch position status signal and the cable side energized status signal, performs logical judgment on the switch position status signal and the cable side energized status signal, and outputs a measurement permission command to the measurement execution module when the judgment condition is met. The measurement execution module receives the measurement permission command, and when the measurement permission command is valid and the insulation resistance measurement activation switch is closed, it starts the DC generator to generate a DC high voltage, and simultaneously controls the phase selection contact to close to construct an insulation resistance measurement circuit. The insulation resistance value is calculated by the current generated in the insulation resistance measurement circuit by the DC high voltage, and the insulation resistance value is sent to the result display module. The result display module receives and displays the insulation resistance value. The result display module also includes a voltmeter installed on the side of the cable to be tested. The voltmeter is used to monitor the voltage across the insulation resistance measurement circuit to verify the circuit integrity.

2. The switchgear insulation resistance measurement system based on a DC generator according to claim 1, characterized in that, The status acquisition module includes a switch position detection unit and a live status detection unit; The switch position detection unit is configured to collect the position information of the switch trolley through a mechanical limit contact linked to the switch operating mechanism, and output a first electrical signal representing the safe position when the switch trolley is in the test position or the moved-out position. The live state detection unit is configured to monitor the cable-side voltage through a normally closed contact connected to the cable-side live display, and output a second electrical signal indicating no voltage when there is no voltage on the cable side. The first electrical signal output by the switch position detection unit and the second electrical signal output by the energized state detection unit are photoelectrically isolated and then input to the interlocking control module as the switch position status signal and the cable-side energized state signal.

3. The switchgear insulation resistance measurement system based on a DC generator according to claim 2, characterized in that, The interlocking control module includes a signal processing unit and a logic judgment unit; The signal processing unit is configured to perform filtering and de-jitter processing on the received first electrical signal and second electrical signal, and output the filtered and de-jittered first electrical signal and second electrical signal. The logic judgment unit is configured to perform a logical AND operation on the filtered and de-jittered first electrical signal and the second electrical signal, and drive the safety relay to engage when both the first electrical signal and the second electrical signal are true. The normally open contact of the safety relay is connected in series in the control circuit of the measurement execution module, and the closing action of the normally open contact constitutes the measurement permission command.

4. The switchgear insulation resistance measurement system based on a DC generator according to claim 3, characterized in that, The measurement execution module includes a DC generation unit and a loop construction unit; The DC generating unit is configured to start after the control circuit is turned on, and process the input power supply into a stable DC high voltage of a set voltage level. The circuit construction unit is configured to receive the stable DC high voltage output by the DC generator unit after the insulation resistance measurement activation switch is closed, and control the phase selection relay to operate in order to construct an insulation resistance measurement circuit to the device under test. The DC generating unit applies the stable DC high voltage to the insulation resistance measurement circuit and calculates the insulation resistance value by measuring the current in the insulation resistance measurement circuit.

5. The switchgear insulation resistance measurement system based on a DC generator according to claim 4, characterized in that, The result display module includes a voltage measurement unit and a status indication unit; The voltage measurement unit is configured to acquire a voltage sampling signal from the insulation resistance measurement circuit, and output the measured voltage value to the status indication unit after voltage division and conditioning. The status indication unit is configured to receive the insulation resistance value and the measured voltage value, and to display the insulation resistance value and the measured voltage value; The status indication unit is configured to compare the measured voltage value with a preset threshold, and trigger an alarm when the measured voltage value is lower than the preset threshold.

6. The switchgear insulation resistance measurement system based on a DC generator according to claim 3, characterized in that, The status indication unit includes a comparator circuit and an alarm driving circuit; The first input terminal of the comparator circuit receives the measured voltage value, and the second input terminal receives the preset threshold. The output of the comparator circuit is connected to the input of the alarm drive circuit; The output of the alarm drive circuit is connected to the audible and visual alarm. When the measured voltage value is lower than the preset threshold, the comparator circuit outputs a level transition signal to the alarm driving circuit, and the alarm driving circuit responds to the level transition signal to drive the audible and visual alarm to issue an alarm.

7. The switchgear insulation resistance measurement system based on a DC generator according to claim 4, characterized in that, The coil circuit of the phase selection relay is connected in series with the contacts of the insulation resistance measurement activation switch and the normally open contacts of the safety relay. The on / off state of the phase selection relay is controlled by the series connection of the contacts of the insulation resistance measurement switch and the normally open contacts of the safety relay.

8. The switchgear insulation resistance measurement system based on a DC generator according to claim 5, characterized in that, The status indication unit includes a verification logic circuit, which pre-stores reference data characterizing the normal correspondence between the insulation resistance value and the measured voltage value. The verification logic circuit receives the insulation resistance value and the measured voltage value, and performs matching calculations between the insulation resistance value and the measured voltage value and the reference data; When the matching calculation result exceeds the preset tolerance range, the verification logic circuit outputs an abnormal signal to the alarm driving circuit to trigger an alarm.

9. The switchgear insulation resistance measurement system based on a DC generator according to claim 1, characterized in that, Also includes: The DC generator, the insulation resistance measurement switch, and the result display module are all installed in one measurement cabinet. The measuring cabinet is connected to the interlocking control module via a set of prefabricated cables, and is connected to the cable side of each switch cabinet on the bus via multiple branch cables; The DC generator inside the measurement cabinet provides the DC high voltage required for insulation resistance measurement to each switch cabinet through the branch cable, thereby completing the centralized measurement of the insulation status of the bus system.

10. The switchgear insulation resistance measurement system based on a DC generator according to claim 9, characterized in that, The insulation resistance measurement switch is a three-position selector switch, which includes an active position, an isolating position, and a closed position. When the three-position selector switch is in the active position, the control circuit of the measurement execution module is activated; When the three-position selector switch is in the isolation position, the connection with the measurement execution module is disconnected. When the three-position changeover switch is in the grounded position, the cable side of the switch cabinet is grounded.

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