Insulation and direct current resistance testing device for auxiliary contacts of high-voltage and low-voltage circuit breakers
By using a high- and low-voltage circuit breaker auxiliary contact insulation and DC resistance testing device, and combining a host computer and a slave computer with relay control contacts to access the circuit, the problem of cumbersome circuit breaker auxiliary contact measurement is solved. This enables fast and accurate insulation resistance and DC resistance measurement, improving work efficiency and reducing labor costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-03-20
AI Technical Summary
High- and low-voltage circuit breakers have a large number of auxiliary contacts that are arranged in a disorderly manner. Existing measurement methods are cumbersome and prone to errors, making it difficult to measure insulation resistance and DC resistance quickly and accurately.
An insulation and DC resistance testing device for auxiliary contacts of high- and low-voltage circuit breakers is adopted. The host computer and the slave computer are connected through a communication line. Combined with the relay control contact access circuit, the insulation resistance and DC resistance of the auxiliary contacts can be measured automatically or manually.
It enables rapid and accurate measurement of the insulation resistance and DC resistance of circuit breaker auxiliary contacts, reducing manual operation, improving work efficiency and reducing labor costs.
Smart Images
Figure CN224019898U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of insulation resistance and direct current resistance test technology, specifically is high, low voltage circuit breaker auxiliary contact insulation and direct resistance testing arrangement. BACKGROUND
[0002] The statements in this part only provide background technical information related to the utility model and do not necessarily constitute prior art.
[0003] High, low voltage circuit breaker is the commonly used power equipment, is used to close or open strong electric circuit. During routine maintenance and maintenance process, high, low voltage circuit breaker needs to carry out periodic preventive inspection, ensures that the internal element of circuit breaker works normally. When checking, will measure, record the direct resistance and insulation resistance of auxiliary contact in the secondary plug, thereby evaluates and judges the performance and working condition of circuit breaker. And in the process of on-site execution, the number of auxiliary contact in the secondary plug is dozens of pairs, and the arrangement order is disorderly, and the insulation and direct resistance measurement work need to be checked, measured and recorded by the staff through the insulation meter and multimeter one by one, the process is tedious and error-prone. UTILITY MODEL CONTENT
[0004] In order to solve the technical problems existing in the background art, the utility model provides high, low voltage circuit breaker auxiliary contact insulation and direct resistance testing arrangement, which measures the insulation resistance and direct current resistance value of high, low voltage circuit breaker auxiliary contact quickly and accurately, judges whether the internal element of switch is normal and whether the mechanical performance is good.
[0005] In order to achieve the above purpose, the utility model adopts the following technical scheme:
[0006] The utility model provides high, low voltage circuit breaker auxiliary contact insulation and direct resistance testing arrangement, including host computer, lower computer and secondary side socket, the host computer is used for sending test instruction to the lower computer and receiving the test data uploaded by the lower computer, the secondary side socket is used for being connected with the high, low voltage circuit breaker to be tested, and the lower computer includes acquisition / processing unit, direct resistance / insulation switching circuit, insulation voltage boost / switching circuit and power supply;The acquisition / processing unit includes AD conversion module, isolation / drive circuit and isolation / drive output state monitoring circuit which are communicated with MCU respectively, and the AD conversion module is connected with direct resistance measurement channel, insulation current measurement channel and insulation voltage measurement channel respectively.
[0007] Further, the acquisition / processing unit is located in the mainboard.
[0008] Further, the direct resistance / insulation switching circuit is located in the relay board, including auxiliary contact switching relay K1-Kn, direct resistance switching relay KΩ and insulation resistance switching relay KG, KMΩ and K0.
[0009] Further, the lower computer collects the output signals of the direct resistance measurement channel, the insulation resistance measurement channel, the insulation voltage measurement channel and the control instruction state signal of the isolation / drive output at a set data sampling period and uploads them to the upper computer for data and state display.
[0010] Further, the lower computer outputs switching control instructions through the corresponding DO port of the isolation / drive circuit according to the relay switching instructions sent by the upper computer to control the corresponding relays to be powered or de-energized, and realizes insulation and direct resistance testing of the auxiliary contact of the high-voltage and low-voltage circuit breaker by using the on or off function of the upstream and downstream circuits of the relay.
[0011] Further, the insulation voltage boosting / switching circuit selects 250V or 500V insulation measurement voltage according to the insulation resistance measurement voltage sent by the upper computer and applies it to the measured contact loop to measure the insulation resistance of the measured contact.
[0012] Further, the direct resistance / insulation switching circuit connects the measured contact to the direct resistance measurement channel, the insulation current measurement channel and the insulation voltage measurement channel according to the control instructions sent by the upper computer.
[0013] Further, when it is necessary to connect the corresponding contact to the direct resistance and insulation resistance measurement circuit, the contact switching instructions sent by the upper computer are output through the isolation / drive circuit, and the relay control instructions are output to make the corresponding relay act; after the relay acts, the two pairs of normally open contacts are closed, and the two ends of the auxiliary contact connected through the high-voltage and low-voltage circuit breaker plug are connected to the two pairs of normally open contacts of the direct resistance switching relay and the insulation switching relay.
[0014] Further, when measuring the direct resistance of the auxiliary contact, the upper computer sends a direct resistance measurement instruction, which is output through the isolation / drive circuit to make the direct resistance switching relay KΩ act, and the two pairs of normally open contacts are closed to connect the two ends of the measured auxiliary contact to the direct resistance measurement channel, and the direct resistance measurement data of the direct resistance measurement channel is read, which is the direct resistance of the measured contact.
[0015] Further, the two pairs of normally closed contacts in the direct resistance switching relay KΩ and the two pairs of normally open contacts in the insulation resistance switching relay KMΩ are connected in series, and the two pairs of normally closed contacts of KG are connected to the ground; when measuring the insulation of the auxiliary contact, the upper computer sends an insulation resistance measurement instruction, which is output through the isolation / drive circuit to make the insulation resistance switching relay KMΩ act, and the two pairs of normally open contacts are closed to connect the measured contact to the insulation current measurement channel, the insulation voltage measurement channel and the insulation voltage boosting / switching circuit in series; the upper computer sends a voltage application instruction, which is output through the isolation / drive circuit to make the relay K0 act to apply the set insulation voltage to the insulation measurement loop; the current and voltage measured by the insulation current measurement channel and the insulation voltage measurement channel are read, and the insulation resistance is calculated according to the current and voltage, which is the insulation resistance of the measured contact.
[0016] Compared with the prior art, the above one or more technical solutions have the following beneficial effects:
[0017] In the insulation and direct resistance measurement of the auxiliary contact of the high-voltage circuit breaker and the low-voltage circuit breaker, the upper computer and the lower computer are connected through the communication line, the lower computer is connected with the secondary plug on the high-voltage circuit breaker and the low-voltage circuit breaker, the upper computer and the lower computer are turned on, after the insulation and direct resistance test is started, the lower computer sends the switching control instruction to the corresponding DO port of the isolation / drive circuit according to the relay switching instruction sent by the upper computer, controls the corresponding relay to be powered on or powered off, and the insulation and direct resistance test of the auxiliary contact of the high-voltage circuit breaker and the low-voltage circuit breaker is realized by using the on-off function of the upstream and downstream circuits of the relay. The relay is used for controlling the corresponding contact to be connected to the circuit, thereby replacing manual insulation test and direct resistance test on the auxiliary contact of the high-voltage circuit breaker and the low-voltage circuit breaker, and then determining whether the internal elements of the switch are normal and whether the mechanical performance is good. BRIEF DESCRIPTION OF DRAWINGS
[0018] The description and the accompanying drawings constitute a part of this application and serve to provide a further understanding of the present application, the illustrative embodiments of the present application and their descriptions serve to explain the present application, and do not constitute an improper limitation on the present application.
[0019] Figure 1 is a structural schematic view of the high-voltage circuit breaker and the low-voltage circuit breaker auxiliary contact insulation and direct resistance test device provided by the present application;
[0020] Figure 2 is a circuit structure schematic view of the high-voltage circuit breaker and the low-voltage circuit breaker auxiliary contact insulation and direct resistance test device provided by the present application;
[0021] Figure 3 is a structural schematic view of the acquisition / processing unit in the high-voltage circuit breaker and the low-voltage circuit breaker auxiliary contact insulation and direct resistance test device provided by the present application;
[0022] Figure 4 is a flowchart schematic view of the high-voltage circuit breaker and the low-voltage circuit breaker auxiliary contact insulation and direct resistance test device provided by the present application when automatic measurement is realized;
[0023] Figure 5 is a flowchart schematic view of the high-voltage circuit breaker and the low-voltage circuit breaker auxiliary contact insulation and direct resistance test device provided by the present application when manual measurement is realized. DETAILED DESCRIPTION
[0024] The present application will be further described below in combination with the drawings and embodiments.
[0025] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the present application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which the present application belongs.
[0026] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used in this specification, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Also, it is to be understood that the term "comprising" or "including" or "having" or "containing" as used herein is intended to indicate the presence of one or more features, steps, operations, devices, components or combinations thereof, but does not exclude the presence or addition of one or more other features, steps, operations, devices, components or combinations thereof.
[0027] As introduced in the background, during the routine maintenance of high and low voltage circuit breakers, the resistance and insulation resistance of the auxiliary contacts inside the circuit breaker are measured and recorded at the secondary plug, so as to evaluate and judge the performance and working condition of the circuit breaker. However, in the process of on-site execution, the number of auxiliary contacts in the secondary plug is large and the order is chaotic, and the insulation and resistance measurement work needs to be checked, measured and recorded one by one by the staff through the insulation meter and the multimeter, which is tedious and prone to errors.
[0028] Therefore, the following embodiments give a high and low voltage circuit breaker auxiliary contact insulation and resistance testing device, which uses a relay to control the corresponding contact to access to the circuit, instead of manually testing the insulation and resistance of the auxiliary contacts of the high and low voltage circuit breaker, so as to judge whether the internal elements of the switch are normal and whether the mechanical performance is good.
[0029] Embodiment one:
[0030] The high and low voltage circuit breaker auxiliary contact insulation and resistance testing device comprises an upper computer, a lower computer and a secondary side socket, the upper computer is used for sending test instructions to the lower computer and receiving test data uploaded by the lower computer, the secondary side socket is used for connecting with the high and low voltage circuit breaker to be tested, and the lower computer comprises an acquisition / processing unit, a resistance / insulation switching circuit, an insulation voltage boosting / switching circuit and a power supply.
[0031] The lower computer collects the output signals of the resistance measurement channel, the insulation resistance measurement channel and the insulation voltage measurement channel and the control instruction state signal of the isolation / drive output at a set data sampling period, and uploads them to the upper computer for data and state display;
[0032] The lower computer outputs switching control instructions through the corresponding DO port of the isolation / drive circuit according to the relay switching instructions sent by the upper computer, controls the corresponding relay to be powered on or powered off, and realizes the insulation and resistance test of the high and low voltage circuit breaker auxiliary contact by using the on or off function of the upstream and downstream circuits of the relay.
[0033] Before testing, select the measurement mode (direct resistance and insulation resistance) and the contact to be measured through the host computer.
[0034] As shown in Figures 1-2 , the device includes a host computer, a lower computer and a secondary side socket.
[0035] The host computer, i.e. the display / operation unit, uses a tablet or a notebook computer installed with corresponding software as the display / operation unit. During use, it serves as the human-machine interface and displays the data uploaded by the data acquisition / processing unit through the serial port or network interface in real time. At the same time, it issues relevant control instructions to the data acquisition and processing unit through operation.
[0036] The lower computer includes an acquisition / processing unit, a direct resistance / insulation switching circuit, an insulation voltage boosting / switching circuit and a power supply.
[0037] The secondary side socket is connected to the high and low voltage circuit breaker plugs, so that the auxiliary contacts in the high and low voltage circuit breakers are connected to the device.
[0038] During use, through the human-machine interface in the display / operation unit, select the contact to be tested, the insulation measurement voltage and its items (direct resistance and insulation resistance). After confirmation, the host computer (i.e. the display / operation unit) in the device controls the direct resistance / insulation switching circuit to connect the auxiliary contacts in the high and low voltage circuit breakers to the direct resistance measurement channel and the insulation measurement channel (which includes the insulation current and insulation voltage measurement channels) in turn, and controls the insulation voltage boosting / switching circuit to output the corresponding voltage level of the insulation measurement voltage. The data in the direct resistance measurement channel, the insulation current measurement channel and the insulation voltage measurement channel are automatically read, the contact direct resistance and insulation resistance are calculated, and the measurement result report is generated.
[0039] As shown in Figure 2 , the direct resistance / insulation switching circuit includes auxiliary contact switching relays K1-Kn, direct resistance switching relays KΩ, and insulation resistance switching relays KG, KMΩ and K0.
[0040] K1-Kn are auxiliary contact switching relays. When it is necessary to connect the corresponding contact to the direct resistance and insulation resistance measurement circuit, the contact switching instruction issued by the display / operation unit is transmitted to the isolation / drive circuit of the acquisition / processing unit, and then the relay control instruction is outputted to make the corresponding relay act. After the relay acts, the two pairs of normally open contacts are closed, and the auxiliary contacts are connected to the two pairs of normally open contacts of the direct resistance switching relays and the insulation switching relays through the high and low voltage circuit breaker plugs.
[0041] KΩ is a direct resistance switching relay. When measuring the direct resistance of auxiliary contacts, the display / operation unit sends a direct resistance measurement instruction, which is sent to the KΩ relay through the isolation / drive circuit of the acquisition / processing unit to make the KΩ relay act. After the KΩ relay acts, the two pairs of normally open contacts are closed, connecting the two ends of the auxiliary contacts to be measured and the direct resistance measurement channel, and the direct resistance measurement data of the direct resistance measurement channel is read, which is the direct resistance of the auxiliary contacts to be measured.
[0042] KG, KMΩ and K0 are insulation resistance switching relays. The two pairs of normally closed contacts of KG and the two pairs of normally open contacts of KMΩ are connected in series, and the two pairs of normally closed contacts of KG are connected to the ground. When measuring the insulation resistance of auxiliary contacts, the display / operation unit sends an insulation resistance measurement instruction, which is sent to the KMΩ relay through the acquisition / processing unit and the isolation / drive circuit to make the KMΩ relay act. After the KMΩ relay acts, the two pairs of normally open contacts are closed, connecting the auxiliary contacts to be measured in series with the insulation current measurement channel, the insulation voltage measurement channel and the insulation voltage boosting / switching circuit. Then, the display / operation unit sends a "voltage application" instruction, which is sent to the K0 relay through the acquisition / processing unit and the isolation / drive circuit to make the K0 relay act to apply the set insulation voltage to the insulation measurement circuit; the current and voltage measured by the insulation current measurement channel and the insulation voltage measurement channel are read, and the insulation resistance is calculated according to the current and voltage, so that the insulation resistance of the auxiliary contacts to be measured is obtained.
[0043] The acquisition / processing unit, as shown in Figure 3 includes an AD conversion module, an isolation / drive circuit and an isolation / drive output state monitoring circuit which are respectively connected to the MCU, and the AD conversion module is connected to the direct resistance measurement channel, the insulation current measurement channel and the insulation voltage measurement channel.
[0044] The MCU: receives the digital signal of the AD conversion module and converts it into the corresponding engineering unit and value (direct resistance, insulation current, insulation voltage), at the same time, calculates the insulation resistance value according to the insulation current and insulation voltage, and uploads the measured direct resistance and calculated insulation resistance value to the display / operation unit in real time; at the same time, receives the instruction signal issued by the display / operation unit and converts it into the corresponding control instruction, which is output through the isolation / drive circuit; the output instruction state is monitored in real time through the isolation / drive output state monitoring circuit, and the consistency of the monitored switch instruction state and the required state is judged and analyzed in real time, and an alarm is sent to the display / operation unit when they are inconsistent.
[0045] The AD conversion module: performs analog-to-digital conversion on the direct resistance, insulation current and insulation voltage signals connected, and uploads the converted digital signal to the MCU for processing.
[0046] The isolation / drive circuit: optoelectronically isolates and amplifies the switch quantity control instruction of the output control switching circuit.
[0047] Isolation / drive output state monitoring circuit: monitor the switch value control command output by the isolation drive circuit, and upload the monitoring result to the MCU for processing and analysis.
[0048] Direct resistance measurement channel: convert the contact direct resistance into corresponding -3-+3V AD sampling voltage.
[0049] Insulation current measurement channel: monitor the current in the insulation resistance measurement loop and convert it into corresponding -3V-+3V AD sampling voltage.
[0050] Direct resistance measurement channel: monitor the insulation resistance measurement loop voltage and convert it into corresponding -3V-+3V AD sampling voltage.
[0051] Direct resistance / insulation switching circuit: according to the control command output by the display / operation unit through the acquisition / processing unit, connect the measured contact with the direct resistance measurement channel, insulation current and insulation voltage measurement channel.
[0052] Insulation voltage boosting / switching circuit: according to the insulation resistance measurement voltage issued by the display / operation unit, select 250V and 500V insulation measurement voltage and apply it in the measured contact loop for measuring the insulation resistance of the measured contact.
[0053] Power supply: provide working power for the data acquisition / processing unit and the insulation voltage boosting / switching circuit. In this embodiment, the device is connected to 220V 50Hz power supply through an adapter for rectification, which serves as the charging power for the charging battery in the device.
[0054] Secondary socket: match the plug of the high and low voltage circuit breaker, and the pin in the socket is connected with the direct resistance / insulation switching circuit.
[0055] In this embodiment, the data processing software is installed in the host computer, and the data acquisition software is installed in the MCU of the lower computer. The host computer and the lower computer exchange data through serial or network communication. When measuring the insulation and direct resistance of the auxiliary contact of the high and low voltage circuit breaker, the MCU, AD conversion circuit and isolation output state in the lower computer measure the input signals of the direct resistance measurement channel, insulation current measurement channel and insulation voltage measurement channel with a data sampling period of 1ms, and upload the DO control command state of the isolation / drive output to the host computer through the serial data line for data and state display. At the same time, the host computer issues the direct resistance and insulation resistance measurement switching command to the MCU of the lower computer through the serial or network data line, and outputs the corresponding switching command through the isolation / drive circuit to control the switching circuit to connect the measured contact with the direct resistance measurement channel, insulation current measurement channel and insulation voltage measurement channel in turn, and complete the contact direct resistance and insulation resistance measurement.
[0056] When the insulation and the direct resistance of the auxiliary contact of the high and low voltage circuit breaker are measured, the upper computer and the lower computer are connected through the communication line, then the lower computer is connected through the secondary plug of the high and low voltage circuit breaker, the upper and lower computers are opened, the insulation and the direct resistance test program is started, and then the insulation and the direct resistance of the auxiliary contact of the circuit breaker can be measured manually and automatically.
[0057] The device has two modes of automatic and manual, in the manual mode, the direct resistance of any auxiliary contact and the insulation resistance between any two lines can be measured, in the automatic mode, after the measurement range (the direct resistance and the insulation resistance) is selected, the direct resistance and the insulation resistance are measured automatically according to the selected measurement range, and the measurement result report is generated.
[0058] According to the test, the original single circuit breaker maintenance needs 2 persons to cooperate and takes 120 min, after using the embodiment, the single person can quickly and accurately test and takes 10 min, the maintenance time is greatly shortened, the work efficiency is improved, and the labor cost is reduced.
[0059] The above only describes preferred embodiments of the utility model and is not used for limiting the utility model, for the person skilled in the art, the utility model can have various changes and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the utility model should be included in the protection scope of the utility model.
Claims
1. A device for testing the insulation and DC resistance of auxiliary contacts of high- and low-voltage circuit breakers, characterized in that, It includes a host computer, a slave computer, and a secondary side socket. The host computer is used to send test commands to the slave computer and receive test data uploaded by the slave computer. The secondary side socket is used to connect to the high-voltage and low-voltage circuit breakers to be tested. The slave computer includes an acquisition / processing unit, a DC resistance / insulation switching circuit, an insulation voltage boosting / switching circuit, and a power supply. The acquisition / processing unit includes an AD conversion module, an isolation / drive circuit, and an isolation / drive output status monitoring circuit, which are respectively connected to the MCU. The AD conversion module is connected to the DC resistance measurement channel, the insulation current measurement channel, and the insulation voltage measurement channel, respectively.
2. The high- and low-voltage circuit breaker auxiliary contact insulation and DC resistance testing device as described in claim 1, characterized in that, The acquisition / processing unit is located in the motherboard.
3. The high- and low-voltage circuit breaker auxiliary contact insulation and DC resistance testing device as described in claim 1, characterized in that, The DC resistance / insulation switching circuit is located in the relay board and includes auxiliary contact switching relays K1-Kn, DC resistance switching relay KΩ, and insulation resistance switching relays KG, KMΩ and K0.
4. The high- and low-voltage circuit breaker auxiliary contact insulation and DC resistance testing device as described in claim 1, characterized in that, The lower-level computer collects the output signals of the DC resistance measurement channel, insulation resistance measurement channel, and insulation voltage measurement channel, as well as the control command status signals of the isolation / drive output, at a set data sampling period, and uploads them to the upper-level computer for data and status display.
5. The high- and low-voltage circuit breaker auxiliary contact insulation and DC resistance testing device as described in claim 1, characterized in that, The lower-level machine outputs a switching control command through the DO port corresponding to the isolation / drive circuit according to the relay switching command sent by the upper-level machine, and controls the corresponding relay to be energized or de-energized. By utilizing the connection or disconnection function of the upstream and downstream circuits of the relay, the insulation and DC resistance test of the auxiliary contacts of the high-voltage and low-voltage circuit breakers can be realized.
6. The high- and low-voltage circuit breaker auxiliary contact insulation and DC resistance testing device as described in claim 1, characterized in that, The insulation voltage boosting / switching circuit selects either 250V or 500V insulation measurement voltage based on the insulation resistance measurement voltage sent by the host computer, and applies it to the circuit of the contact being tested to perform insulation resistance measurement of the contact being tested.
7. The high- and low-voltage circuit breaker auxiliary contact insulation and DC resistance testing device as described in claim 1, characterized in that, The DC resistance / insulation switching circuit connects the contact to be measured to the DC resistance measurement channel, the insulation current measurement channel, and the insulation voltage measurement channel respectively, according to the control instructions issued by the host computer.
8. The high- and low-voltage circuit breaker auxiliary contact insulation and DC resistance testing device as described in claim 7, characterized in that, When it is necessary to connect the corresponding contacts to the DC resistance and insulation resistance measurement circuit, the contact switching command issued by the host computer is sent through the isolation / drive circuit and then outputs the relay control command to make the corresponding relay operate. After the relay operates, the two normally open contacts close, and the two ends of the auxiliary contacts are connected to the two normally open contacts of the DC resistance switching relay and the insulation switching relay through the high and low voltage circuit breaker plugs.
9. The high- and low-voltage circuit breaker auxiliary contact insulation and DC resistance testing device as described in claim 7, characterized in that, When measuring the DC resistance of the auxiliary contact, the host computer sends a DC resistance measurement command. After passing through the isolation / drive circuit, the DC resistance switching relay KΩ is activated, and the two normally open contacts close, connecting the two ends of the auxiliary contact to be measured to the DC resistance measurement channel. The measurement data of the DC resistance measurement channel is then read, which is the DC resistance of the contact to be measured.
10. The high- and low-voltage circuit breaker auxiliary contact insulation and DC resistance testing device as described in claim 7, characterized in that, The two normally closed contacts of the DC resistance switching relay KΩ and the two normally open contacts of the insulation resistance switching relay KMΩ are connected in series. The two normally closed contacts of KG are connected to "ground". When measuring the insulation of the auxiliary contact, the host computer sends an insulation resistance measurement command. After passing through the isolation / drive circuit, the insulation resistance switching relay KMΩ is activated, and the two normally open contacts close, connecting the contact to be measured in series with the insulation current measurement channel, the insulation voltage measurement channel, and the insulation voltage boost / switching circuit. The host computer sends a voltage application command, which, after passing through the isolation / drive circuit, activates the relay K0 to apply the set insulation voltage to the insulation measurement circuit. The current and voltage measured by the insulation current measurement channel and the insulation voltage measurement channel are read, and the insulation resistance is calculated based on the current and voltage, thus obtaining the insulation resistance of the contact to be measured.