A kind of strain clamp direct current resistance internet of things testing device and method

Abstract

This invention relates to the field of power fitting testing technology, specifically to an IoT testing device and method for the DC resistance of tension clamps. The device includes a portable housing and a built-in testing host. The host has a main control unit electrically connected to a wireless network module, a positioning module, a constant current source, and a voltage sampling and temperature acquisition module. The host is connected to a four-terminal clamp, whose clamp arms integrate independent current and voltage probes. Elastic springs are fitted to the probe tails, and the clamp is equipped with a contact temperature sensor. After clamping, a current I is applied and the voltage drop U is measured to calculate the measured resistance R_meas. The material temperature coefficient α is obtained and corrected to the resistance value R0 at standard temperature using the formula R0=R_meas / [1+α×(T1-T0)]. The data is packaged and uploaded to a cloud platform via the wireless module for historical trend comparison and early warning output. This invention uses a Kelvin four-terminal structure to eliminate lead resistance, combined with contact temperature measurement and intelligent analysis on the cloud platform, significantly improving the accuracy of DC resistance testing and the efficiency of operation and maintenance management.

Description

Technical Field

[0001] This invention relates to the field of power fittings testing technology, specifically to an IoT testing device and method for the DC resistance of tension clamps. Background Technology

[0002] Tension clamps are key hardware in transmission lines that bear the tension of conductors and conduct current. Under long-term operation, their contact resistance increases due to aging, oxidation or poor crimping, which can lead to increased energy consumption, local overheating or even line breakage. Therefore, DC resistance testing is a core operation and maintenance task.

[0003] Existing methods mostly rely on manual operation of micro-ohmmeters, which has four major problems: ① Manual testing is inefficient and prone to errors; ② Two-wire systems cannot eliminate interference from lead / contact resistance, and four-wire systems lack environmental adaptability; ③ There is no temperature compensation, making the results incomparable; ④ Data is recorded in a scattered manner or stored locally, making real-time sharing impossible and hindering intelligent management.

[0004] To address the aforementioned issues, there is an urgent need for a high-precision testing device and method with automatic temperature compensation and integration with the Internet of Things. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an IoT testing device and method for the DC resistance of tension clamps, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an IoT testing device for the DC resistance of a tension clamp, comprising a portable housing and a cover hinged to the housing, wherein a testing host is installed inside the portable housing, the testing host is equipped with a main control unit, and the main control unit is electrically connected to a wireless network module, a positioning module, a constant current source module, an operation panel, a voltage sampling module, and a temperature acquisition module; the panel of the testing host is respectively embedded with a testing terminal, a power input terminal, a printing module, an indicator meter, and an indicator light; wherein, the testing terminal is pluggably connected to a four-terminal testing fixture, the four-terminal testing fixture comprising a left clamping arm, a right clamping arm, and a tension clamp body.

[0007] Preferably, the four-terminal test fixture is a Kelvin four-terminal structure. The left and right clamping arms each integrate independent current and voltage electrodes. The current electrode is located on the outside of the clamping arm, and the voltage electrode is located on the inside of the clamping arm. The left and right clamping arms are also each provided with a voltage probe and a current probe. The tail rods of the voltage probe and the current probe are each fitted with an elastic compression spring. The voltage probe and the current probe are both made of gold-plated copper alloy material.

[0008] Preferably, an insulating thermally conductive pad and a contact temperature sensor are provided on one side of the left clamp arm corresponding to the tension clamp body, and the contact temperature sensor is in close contact with the surface of the tension clamp body through the insulating thermally conductive pad.

[0009] Preferably, the contact temperature sensor is also electrically connected to a sensor signal line, and the contact temperature sensor is connected to the temperature acquisition module of the test host via the sensor signal line.

[0010] Preferably, the constant current source module is a programmable constant current source that can output multiple levels of constant test current within the range of 1A to 100A, and can automatically switch between forward and reverse test current under the control of the main control unit.

[0011] Preferably, the voltage sampling module includes a high-precision analog-to-digital converter for acquiring weak voltage signals between the voltage terminals of the four-terminal test fixture.

[0012] Preferably, the temperature acquisition module includes an ambient temperature and humidity sensor and a contact temperature sensor, used to acquire the ambient temperature and the surface temperature of the tension clamp body.

[0013] Preferably, the positioning module is a GPS or BeiDou positioning module; the wireless network module is a 4G / 5G communication module; the printing module is a thermal printer; the indicator is an analog pointer meter; and the indicator lights include a power indicator, a test status indicator, and an alarm indicator.

[0014] A method for testing the DC resistance of a tension clamp for IoT applications, the method being implemented using the aforementioned tension clamp DC resistance IoT testing device, includes the following steps:

[0015] S1: Clamp the four-terminal test fixture onto the test part of the tension clamp to be tested, so that a pair of current probes and a pair of voltage probes make reliable contact with the test points of the tension clamp respectively. At the same time, the surface temperature T1 of the tension clamp is detected by the contact temperature sensor set on the fixture, and the ambient temperature T2 and ambient humidity H are detected by the ambient temperature and humidity sensor.

[0016] S2: The constant current source module of the test host applies a preset test current I to the tension clamp, while the voltage sampling module collects the voltage drop U across the test part of the tension clamp through the voltage probe.

[0017] S3: The main control unit calculates the measured resistance value R_meas=U / I of the tension clamp at the current temperature according to Ohm's law;

[0018] S4: The main control unit acquires the material information of the tension clamp body and, based on the preset material temperature coefficient α, corrects the measured resistance value R_meas to the standard resistance value R0 at the standard reference temperature T0. The correction formula is:

[0019] R0 = R_meas / [1 + α × (T1 - T0)];

[0020] Wherein, T0 is the preset standard reference temperature, T0=20℃, and α is the temperature coefficient of resistance of the tension clamp material near the standard reference temperature (20℃);

[0021] S5: The main control unit packages the standard resistance value R0, the measured resistance value R_meas, the surface temperature of the tension clamp T1, the ambient temperature T2, the ambient humidity H, and the test current I data, and uploads them to the Internet of Things cloud platform through the wireless communication module.

[0022] S6: The IoT cloud platform receives and stores test data, compares and analyzes the standard resistance value R0 with the historical test data and preset qualified threshold of the tension clamp, determines whether the conductivity of the tension clamp meets the requirements, and outputs operation and maintenance early warning information based on the data analysis results.

[0023] Preferably, the typical values ​​of the material temperature coefficient α are as follows: α is 0.00393 / ℃ for pure copper, α is 0.00403 / ℃ for aluminum alloy, and α is 0.0060 / ℃ for cast steel (all of the above are approximate values ​​at a standard reference temperature of 20℃). The main control unit has a pre-stored temperature coefficient comparison table for different materials. When the user remotely selects the material type of the tension clamp to be tested through the operation panel (4) or the Internet of Things cloud platform, the main control unit automatically calls the corresponding α value for temperature correction.

[0024] Preferably, in step S2, the value of the test current I applied by the constant current source module is determined according to the nominal current carrying capacity of the tension clamp, so that the test current density is comparable to the normal operating current density of the tension clamp.

[0025] Preferably, step S2 further includes a step of multiple measurements: performing N repeated measurements on the same point under the same test conditions, where N≥3, calculating the average value of the N measurement results as the final measured resistance value R_meas, and simultaneously calculating the relative standard deviation RSD of the measurement results. If the RSD exceeds a preset deviation threshold, a measurement stability alarm signal is issued.

[0026] Preferably, the material temperature coefficient α in step S4 is pre-stored in the memory of the main control unit. The user can remotely configure the material type of the tension clamp to be tested through the operation panel (4) or the Internet of Things cloud platform, and the main control unit will automatically call the corresponding material temperature coefficient for temperature correction.

[0027] Preferably, in step S6, the IoT cloud platform uses a time-series-based data analysis algorithm to perform trend analysis on the test data of the same tension clamp. When the growth rate of the standard resistance value R0 exceeds the preset warning threshold, the platform automatically generates a warning message and pushes it to the terminal of the designated maintenance personnel.

[0028] Preferably, in step S6, the IoT cloud platform marks the test data on the corresponding transmission line section of the electronic map based on the test location information obtained by the GPS / BeiDou positioning module, forming a spatial distribution heat map of the DC resistance of the tension clamp.

[0029] Preferably, the test device also includes a self-testing step: before each test, by clamping the four-terminal test fixture onto the standard resistor calibrator, the accuracy of the constant current source module output current and the measurement accuracy of the voltage sampling module are automatically verified. If the verification error exceeds ±0.5%, the device is prompted to return to the factory for calibration.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. Measurement accuracy is significantly improved:

[0032] This invention employs a Kelvin four-terminal test fixture, with the current probe and voltage probe operating independently, effectively eliminating the influence of lead resistance and contact resistance on the measurement results. The voltage sampling module uses a 24-bit high-precision Σ-Δ ADC, coupled with an instrumentation amplifier, capable of resolving weak voltage signals at the 1μV level, making micro-ohm level resistance measurement possible. The constant current source module has an output current stability better than 0.1% and supports multiple output levels from 1A to 100A, allowing selection of appropriate current based on clamp specifications to ensure a high signal-to-noise ratio. By switching between forward and reverse current measurements and averaging the values, the system error introduced by thermoelectric potential is effectively eliminated.

[0033] 2. Accurate temperature compensation and strong comparability of results:

[0034] This invention obtains the real-time temperature of the tension clamp by placing a contact temperature sensor on the clamp, which directly contacts the surface of the clamp body, instead of relying on ambient temperature estimation. Simultaneously, it collects ambient temperature and humidity data to provide auxiliary judgment for measurements under abnormal environmental conditions. The main control unit incorporates the temperature coefficient of resistance α for various metal materials (copper, aluminum alloy, cast steel, etc.), allowing users to remotely configure the material. The system automatically calls the corresponding coefficient for correction, and the main control unit then converts the R... 20 Package the following information: R, T, test current range, test timestamp, and geographic location information.

[0035] Correction formula: R 20 =R_meas / [1+α·(T-20)];

[0036] Among these measures, the measured values ​​are uniformly converted to the equivalent resistance at a standard temperature of 20℃, making the test data from different seasons and regions directly comparable.

[0037] 3. Testing efficiency is greatly improved, and manual intervention is reduced:

[0038] Traditional manual micro-ohmmeter testing requires multiple people and manual recording, with a single-point test taking 5-10 minutes. This invention's fixture can automatically complete the entire process of current application, voltage acquisition, forward / reverse switching, multiple repeated measurements, temperature correction, and data upload with a single clamping, reducing single-point test time to less than 1 minute. It supports N≥3 repeated measurements and automatically calculates the average value and relative standard deviation (RSD). If the RSD exceeds the threshold, an alarm is automatically triggered, eliminating the need for manual verification of data validity. Test reports can be thermally printed on-site or stored in the cloud, essentially eliminating the problems of errors and data loss associated with manual recording.

[0039] 4. IoT functionality enables remote monitoring and intelligent early warning:

[0040] This invention utilizes a 4G / 5G wireless communication module to upload test data to an IoT cloud platform in real time. Administrators can remotely view the latest and historical resistance values ​​of any tension clamp. The cloud platform incorporates a time-series-based trend analysis algorithm to automatically track the resistance change trend of the same tension clamp across multiple tests. If the resistance value rises continuously and the growth rate exceeds a preset threshold (e.g., a cumulative increase of 10%), a degradation warning is immediately generated and pushed to maintenance personnel's mobile app or via SMS. Combined with GPS / BeiDou positioning information, the resistance health status of all tension clamps on the entire line is displayed on an electronic map in the form of a heat map (green for normal, yellow for caution, red for alarm), facilitating the overall planning of maintenance priorities and avoiding blind inspections.

[0041] 5. Device self-test and fault indication ensure test reliability:

[0042] Before each test, the device automatically clamps a standard resistor calibrator to verify the accuracy of the constant current source output current and voltage sampling accuracy. If the error exceeds ±0.5%, it prompts the device to return to the factory for calibration, thus preventing testing with defects. The indicator light system (power, test status, alarm) provides intuitive feedback on the device's operating status and test results, allowing on-site operators to determine the current situation without having to check the screen. During the measurement process, if there is poor contact or abnormal environment (such as RSD exceeding the threshold or temperature exceeding the reasonable range), an audible and visual alarm is automatically issued to prevent erroneous data from being mixed into the normal records.

[0043] 6. Portability and adaptability to different situations:

[0044] This invention integrates the entire device into a portable case, with the case hinged to the lid. The internal modules are compactly arranged, making it lightweight and easy to carry to field power transmission line sites. The clamps use an elastic compression spring design, and the probes are made of gold-plated copper alloy, which is wear-resistant and oxidation-resistant, ensuring reliable contact after multiple insertions and removals. The built-in or external power adapter supports AC-220V power supply and can also be equipped with a battery module to adapt to remote tower sites without mains power.

[0045] 7. Data management and operation and maintenance decision support:

[0046] This invention centrally stores historical data through a cloud platform, supports retrieval by line, tower number, time range, and other conditions, and facilitates the generation of operation and maintenance reports; it supports remote configuration of parameters such as test current level, material coefficient, and alarm threshold without on-site equipment modification, and adapts to the testing needs of different lines and clamps of different materials; it can be connected to third-party operation and maintenance management systems (such as transmission line status monitoring platforms) via API to achieve data sharing and linkage early warning.

[0047] 8. Enhanced security:

[0048] This invention features a constant current source module with an extremely low output voltage (typically below 10V), eliminating the risk of electric shock and ensuring operator safety. Automatic forward and reverse switching avoids short circuits or misoperations that may occur during manual wire replacement. When the resistance value is too high (such as when the wire clamp is severely broken or open-circuited), the constant current source automatically limits the voltage to prevent equipment damage. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0050] Figure 2 This is a schematic diagram of the structure of the test host of the present invention;

[0051] Figure 3 This is a schematic diagram of the four-end test fixture of the present invention.

[0052] Figure 4 This is a system structure block diagram of the testing device of the present invention;

[0053] Figure 5 This is a flowchart of the Internet of Things (IoT) test method for the DC resistance of tension clamps according to the present invention.

[0054] The diagram shows the following components: 1. Portable housing; 2. Lid; 3. Test host; 4. Control panel; 5. Wireless network module; 6. Test terminal; 7. Power input terminal; 8. Printing module; 9. Indicator; 10. Ambient temperature and humidity sensor; 11. Indicator light; 12. Four-terminal test clamp; 13. Right clamping arm; 14. Tension clamp body; 15. Left clamping arm; 16. Voltage probe; 17. Elastic compression spring; 18. Insulating thermal pad; 19. Contact temperature sensor; 20. Sensor signal line; 21. Current probe. Detailed Implementation

[0055] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0056] Example 1

[0057] like Figure 1-5 As shown, this embodiment discloses an IoT testing device and method for the DC resistance of tension clamps. It includes a portable housing 1 and a cover 2 hinged to the housing. A test host 3 is installed inside the portable housing 1. The test host 3 is equipped with a main control unit, which is electrically connected to a wireless network module 5, a positioning module, a constant current source module, an operation panel 4, a voltage sampling module, and a temperature acquisition module. The test host 3 is also connected to a test terminal 6, a power input terminal 7, a printing module 8, an indicator 9, and an indicator light 11. The test terminal 6 is pluggably connected to a four-terminal test fixture 12, which includes a left clamping arm 15, a right clamping arm 13, and a tension clamp body 14.

[0058] In this embodiment, the positioning module can be a GPS or Beidou positioning module; the wireless network module 5 can be a 4G / 5G communication module; the printing module 8 can be a thermal printer; and the indicator 9 is an analog pointer meter.

[0059] Indicator light 11 includes a power indicator light with a single green LED, a test status indicator light with three-color green, yellow, and red LEDs, and an alarm indicator light with a single red LED.

[0060] The power indicator light serves to indicate whether the device is powered on correctly.

[0061] Working principle:

[0062] When the test host 3 is connected to AC-220V power supply or internal battery power supply (if any) through power input terminal 7, the main control unit detects a stable working voltage, which drives the power indicator light to light up (usually a solid green light).

[0063] If the power supply voltage is abnormal (too low or too high), the indicator light may flash or not light up, and the alarm indicator light may be triggered simultaneously.

[0064] The function of the test status indicator light is to reflect the current test progress and status.

[0065] Working principle:

[0066] Standby mode: Indicator light off or constantly on with a weak light (such as yellow).

[0067] During testing: When the main control unit starts the constant current source module and controls the voltage sampling module to collect data, the test status indicator light will flash slowly (e.g., 1Hz, green) to remind the operator not to disassemble the fixture.

[0068] Test complete: After the data has been read and the resistance value has been successfully calculated, the indicator light will stay on (green) for a few seconds, indicating that the result can be read or the next test can be performed.

[0069] Abnormal Interruption: If the constant current source output exceeds the limit, the voltage sampling value overflows, or the contact is poor (such as the relative standard deviation RSD exceeding the threshold) occurs during the measurement process, the main control unit will make the test status indicator flash rapidly (such as 5Hz, red) and the alarm indicator will light up.

[0070] The function of the alarm indicator light is to indicate that the measurement result exceeds the standard or that the device has a self-test / operational failure.

[0071] Working principle:

[0072] Self-test failure: If the standard resistor calibration error is ≥ ±0.5% during the device's self-test procedure, the main control unit will drive the alarm indicator light to stay on (red) and simultaneously prompt "Return to factory for calibration".

[0073] Measured value exceeds threshold: Resistance value R after temperature compensation 20 When the threshold set in the cloud or locally is exceeded, the main control unit will keep the alarm indicator light on or flash slowly (red), and can upload the alarm information through the wireless network module 5.

[0074] Temperature / Environmental Abnormality: If the reading of the ambient temperature and humidity sensor 10 or the contact temperature sensor 19 exceeds the reasonable range (e.g., temperature > 80℃), the alarm indicator light will flash (red), indicating that the environment is not suitable for testing or the clamp is overheated.

[0075] Communication / Storage Failure: Data fails to upload after packaging or local storage is full. The alarm indicator flashes briefly and then alternates with the test status indicator to prompt maintenance personnel to check.

[0076] In this embodiment, the test host 3 has an operation panel 4 embedded on its panel as a human-computer interaction interface. The operation panel 4 has an overall vertical layout structure. The upper part of the operation panel is provided with an LCD screen, which constitutes a measurement result display area for real-time display of key data and status information during the test process. Specifically, this includes: the current test current value I applied by the constant current source module, the voltage drop U collected by the voltage sampling module, the measured resistance value R_meas calculated by the main control unit at the current temperature, the standard resistance value R0 after temperature correction, the surface temperature T1 of the tension clamp body, the ambient temperature T2 and the ambient humidity H, and the relative standard deviation RSD after multiple repeated measurements.

[0077] Meanwhile, the LCD screen can also display current test progress prompts (such as "Self-testing", "Testing", "Data uploading", "Test completed"), equipment operating status, and alarm information.

[0078] The lower part of the control panel features a set of function buttons, including a "Measure" button, a "Reset" button, a "Select" button, and an "OK" button. These four buttons are arranged in a row, and their functions are as follows:

[0079] "Measurement" button: After clamping the four-terminal test fixture and confirming that the wiring is correct, the operator presses this button, and the main control unit will start a complete automatic test according to the preset process, sequentially executing steps such as constant current source application, voltage acquisition, resistance calculation, temperature correction, and data packaging and uploading, without the need for manual intervention.

[0080] The "Reset" button is used to restore the main control unit to its initial standby state, clear the current measurement data, and stop the output of the constant current source module when the test is interrupted abnormally, the parameter settings are incorrect, or the test needs to be restarted, ensuring operational safety.

[0081] The "Select" button is used to cycle through the available items in the menu interface of the LCD screen. By pressing this button continuously, the operator can select the material type of the tension clamp to be tested (such as pure copper, aluminum alloy, cast steel, etc.), the test current range (such as 1A, 5A, 10A, 50A, 100A), or view historical test records. The selected item is displayed on the screen in a highlighted or reversed manner.

[0082] "OK" button: Used to confirm the execution of the menu item selected by the "Select" button. For example, when the operator switches to the corresponding material type by using the "Select" button, pressing the "OK" button completes the material selection. The main control unit automatically calls the resistance temperature coefficient α value corresponding to the material for subsequent temperature correction. When switching to the target current range, pressing the "OK" button locks the range, and the constant current source module outputs the test current according to the selected value.

[0083] In addition, the operation panel is equipped with indicator lights 11, including a power indicator light, a test status indicator light, and an alarm indicator light, which are used to indicate the power-on status of the device, the current test process status, and whether the measurement result exceeds the threshold or whether the device is abnormal, respectively. An indicator table 9 is also provided on one side of the operation panel. This indicator table is an analog pointer table, which is used to roughly reflect the current test current or voltage change trend in real time during the test, so that the on-site operator can quickly judge whether the constant current source output is stable without observing the LCD screen.

[0084] In this embodiment, the panel of the test host is equipped with a socket as a test terminal. The four-terminal test fixture achieves pluggable electrical connection through a plug that matches the test socket and extends from its tail. The four-terminal test fixture includes a left clamping arm 15 and a right clamping arm 13, which are hinged together by a pivot to form a clamping body for clamping the tension clamp body 14. It also includes a pair of current probes 21 as current output terminals, marked as C1 and C2, which are electrically connected to the constant current source module of the test host.

[0085] And a pair of voltage probes 16 are voltage sampling terminals, marked P1 and P2, which are electrically connected to the voltage sampling module of the test host;

[0086] Both the current probe and the voltage probe are made of gold-plated copper alloy. The elastic compression spring 17 is sleeved at the tail of the current and voltage probes to press the probe against the test surface of the tension clamp with a constant pressure of 2N to 5N and adapt to the change of clamp thickness. At the same time, a guide sleeve is provided between the probe and the clamp housing. The guide sleeve is provided with a polytetrafluoroethylene insulating bushing that fits against the probe, so that its insulation resistance is greater than 100MΩ (500V test voltage).

[0087] Structure and working principle of elastic compression spring 17:

[0088] Structure: The spring is sleeved at the tail of the probe, with one end resting on the probe step and the other end resting on the inner end face of the guide sleeve.

[0089] Static (free state): The spring is in a pre-compressed or free length state, the probe extends and is limited by the limiting ring, which is fixed to the front end of the probe (i.e. the measuring end), and the probe moves along with the limiting ring.

[0090] Dynamic (Compression State): The clamp holds the object under test (tension clamp body 14), and the tip of the probe is pushed back. The spring is compressed, and the spring force (F=K·x) increases.

[0091] Function: Provides stable and controllable contact pressure (2N~5N) regardless of thickness variation (due to low spring stiffness, pressure variation is small), ensuring low contact resistance while avoiding damage to the clamp or probe.

[0092] The four-terminal test fixture is also equipped with an insulating thermally conductive pad 18 and a contact temperature sensor 19. The insulating thermally conductive pad is attached to the inner side of the clamping body, and the contact temperature sensor is tightly attached to the surface of the tension clamp body 14 through the insulating thermally conductive pad 18. The contact temperature sensor 19 is connected to the temperature acquisition module of the test host through the sensor signal line 20.

[0093] The temperature sensor 19 has its temperature probe embedded in the probe mounting base of the clamping body, with the probe tip protruding slightly from the probe tip by 0.2mm to 0.5mm to ensure that the clamping device makes priority contact with the wire clamp surface when clamping.

[0094] Both the current probe 21 and the voltage probe 16 are connected to the corresponding interface of the test host via soft copper braided wire. A polytetrafluoroethylene or ceramic insulating bushing is provided between the probe and the clamping body to make the insulation resistance between the probe and the clamping shell greater than 100MΩ. In the four-terminal test clamp, the tip length of the voltage probe 16 is 0.3mm longer than the tip length of the current probe 21, so that the voltage probe contacts the tension clamp before the current probe during clamping and detaches from the current probe after the current probe during release, so as to protect the voltage sampling circuit from the impact of the test current.

[0095] Example 2

[0096] like Figure 1-5 As shown, this embodiment discloses an IoT testing device and method for the DC resistance of a tension clamp. It includes a portable housing 1 and a cover 2 hinged to the housing. A test host 3 is installed inside the portable housing 1. The test host 3 is equipped with a main control unit. The main control unit is electrically connected to a wireless network module 5, a positioning module, a constant current source module, an operation panel (4), a voltage sampling module, and a temperature acquisition module. The test host 3 is also connected to a test terminal 6, a power input terminal 7, a printing module (8), an indicator 9, and an indicator light 11. The test terminal 6 is pluggably connected to a four-terminal test fixture 12. The four-terminal test fixture 12 includes a left clamping arm 15, a right clamping arm 13, and a tension clamp body 14.

[0097] In this embodiment, the test host 3 integrates a main control unit, which adopts an ARM-Cortex-M series microcontroller to be responsible for logic control, data acquisition and communication protocol processing. The constant current source module adopts a high-precision DAC to control the MOSFET array, and the output current stability is better than 0.1%. The voltage sampling module adopts a 24-bit Σ-Δ ADC (Sigma-Delta analog-to-digital converter), which, together with the instrumentation amplifier, can distinguish voltage signals at the 1μV level.

[0098] In this embodiment, after the four-terminal test fixture is clamped, the system automatically performs a self-test: first, it measures the standard resistance range; if the error exceeds ±0.5%, it prompts the system to return the device to the factory for calibration to ensure test reliability.

[0099] In this embodiment, the contact temperature sensor 19 is attached to the surface of the tension clamp body 14 to monitor the body temperature in real time; the ambient temperature and humidity sensor 10 collects the ambient temperature and humidity. The main control unit prioritizes the clamp body temperature for compensation, and automatically switches to the ambient temperature as a backup if the body temperature sensor is abnormal.

[0100] In this embodiment, after receiving the data, the cloud platform uses a time series analysis algorithm to fit the historical resistance values ​​of the same tension clamp to a trend. When the resistance values ​​are monotonically increasing for three consecutive measurements and the cumulative rate of change exceeds 10%, an "early warning of deterioration trend" is automatically generated and pushed to the mobile APP of the maintenance personnel.

[0101] In addition, the cloud platform supports electronic map heat map display, which marks the resistance health status of each clamp with different colors, making it easier for maintenance units to coordinate maintenance plans.

[0102] A device and method for testing the DC resistance of tension clamps for Internet of Things (IoT) applications, comprising the following steps:

[0103] S1: Clamp the four-terminal test fixture onto the test part of the tension clamp to be tested, so that a pair of current probes and a pair of voltage probes make reliable contact with the test points of the tension clamp respectively. At the same time, the surface temperature T1 of the tension clamp is detected by the contact temperature sensor set on the fixture, and the ambient temperature T2 and ambient humidity H are detected by the ambient temperature and humidity sensor.

[0104] S2: The constant current source module of the test host applies a preset test current I to the tension clamp, while the voltage sampling module collects the voltage drop U across the test part of the tension clamp through the voltage probe.

[0105] S3: The main control unit calculates the measured resistance value R_meas=U / I of the tension clamp at the current temperature according to Ohm's law;

[0106] S4: The main control unit acquires the material information of the tension clamp body and, based on the preset material temperature coefficient α, corrects the measured resistance value R_meas to the standard resistance value R0 at the standard reference temperature T0. The correction formula is:

[0107] R0 = R_meas / [1 + α × (T1 - T0)];

[0108] Where T0 is the preset standard reference temperature, and α is the temperature coefficient of resistance of the tension clamp material near the standard reference temperature.

[0109] S5: The main control unit packages the standard resistance value R0, the measured resistance value R_meas, the surface temperature of the tension clamp T1, the ambient temperature T2, the ambient humidity H, and the test current I data, and uploads them to the Internet of Things cloud platform through the wireless communication module.

[0110] S6: The IoT cloud platform receives and stores test data, compares and analyzes the standard resistance value R0 with the historical test data and preset qualified threshold of the tension clamp, determines whether the conductivity of the tension clamp meets the requirements, and outputs operation and maintenance early warning information based on the data analysis results.

[0111] In step S2, the value of the test current I applied by the constant current source module is determined according to the nominal current carrying capacity of the tension clamp, so that the test current density is comparable to the normal operating current density of the tension clamp.

[0112] Step S2 also includes a step of multiple measurements: under the same test conditions, the same point is measured N times repeatedly, N≥3, and the average value of the N measurement results is calculated as the final measured resistance value R_meas. At the same time, the relative standard deviation RSD of the measurement results is calculated. If RSD exceeds the preset deviation threshold, a measurement stability alarm signal is issued.

[0113] The material temperature coefficient α in step S4 is pre-stored in the memory of the main control unit. The user can remotely configure the material type of the tension clamp to be tested through the operation panel (4) or the Internet of Things cloud platform. The main control unit automatically calls the corresponding material temperature coefficient for temperature correction.

[0114] In step S6, the IoT cloud platform uses a time-series-based data analysis algorithm to perform trend analysis on the test data of the same tension clamp. When the growth rate of the standard resistance value R0 exceeds the preset warning threshold, it automatically generates a warning message and pushes it to the terminal of the designated maintenance personnel.

[0115] In step S6, the IoT cloud platform marks the test data on the corresponding transmission line section of the electronic map based on the test location information obtained by the GPS / BeiDou positioning module, forming a spatial distribution heat map of the DC resistance of the tension clamp.

[0116] It also includes a self-testing step for the testing device: before each test, by clamping the four-terminal test fixture onto the standard resistor calibrator, the accuracy of the constant current source module output current and the measurement accuracy of the voltage sampling module are automatically verified. If the verification error exceeds ±0.5%, the device is prompted to return to the factory for calibration.

[0117] The foregoing has shown and described the basic principles and main features of the present invention and its advantages. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description. Therefore, it is intended to include variations falling within the meaning and scope of equivalents of the claims within the present invention, and no reference numerals in the claims should be regarded as limiting the scope of the claims.

[0118] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A DC resistance IoT testing device for strain clamp, characterized in that: It includes a portable housing (1) and a lid (2) hinged to the housing. The portable housing (1) is equipped with a test host (3). The test host (3) is equipped with a main control unit. The main control unit is electrically connected to a wireless network module (5), a positioning module, a constant current source module, an operation panel (4), a voltage sampling module, and a temperature acquisition module. The test host (3) is equipped with a test terminal (6), a power input terminal (7), a printing module (8), an indicator (9) and an indicator light (11) on its panel. The test end (6) is pluggably connected to a four-terminal test fixture (12), which includes a left clamping arm (15), a right clamping arm (13), and a tension clamp body (14).

2. The DC resistance testing device for the strain clamp of claim 1, wherein: The left clamping arm (15) and the right clamping arm (13) each integrate independent current electrodes and voltage electrodes, with the current electrodes located on the outside of the clamping arm and the voltage electrodes located on the inside of the clamping arm.

3. The IoT testing device for DC resistance of tension clamps according to claim 2, characterized in that: The left clamping arm (15) and the right clamping arm (13) are respectively provided with voltage probes (16) and current probes (21) for the corresponding current electrodes and voltage electrodes. The tail rods of the voltage probes (16) and current probes (21) are each fitted with elastic compression springs (17). The voltage probes (16) and current probes (21) are both made of gold-plated copper alloy material.

4. The IoT testing device for DC resistance of tension clamps according to claim 2, characterized in that: An insulating thermal pad (18) and a contact temperature sensor (19) are provided on one side of the left clamp arm (15) corresponding to the tension clamp body (14). The contact temperature sensor (19) is in close contact with the surface of the tension clamp body (14) through the insulating thermal pad (18).

5. The IoT testing device for DC resistance of tension clamps according to claim 4, characterized in that: The contact temperature sensor (19) is also electrically connected to a sensor signal line (20), and the contact temperature sensor (19) is connected to the temperature acquisition module of the test host (3) via the sensor signal line (20).

6. The IoT testing device for DC resistance of tension clamps according to claim 1, characterized in that: The constant current source module is a programmable constant current source that can output multiple levels of constant test current within the range of 1A to 100A, and automatically switch between forward and reverse test current under the control of the main control unit.

7. The IoT testing device for DC resistance of tension clamps according to claim 1, characterized in that: The voltage sampling module (9) includes a high-precision analog-to-digital converter for acquiring weak voltage signals between the voltage terminals of the four-terminal test fixture (12).

8. The IoT testing device for DC resistance of tension clamps according to claim 1, characterized in that: The temperature acquisition module includes an ambient temperature and humidity sensor (10) and a contact temperature sensor (19) for acquiring ambient temperature and the surface temperature of the tension clamp body.

9. A method for testing the DC resistance of a tension clamp for Internet of Things (IoT) applications, wherein the method is implemented using the tension clamp DC resistance IoT testing device as described in any one of claims 1-8, characterized in that... Includes the following steps: S1: Clamp the four-terminal test fixture onto the test part of the tension clamp to be tested, so that a pair of current probes and a pair of voltage probes make reliable contact with the test points of the tension clamp respectively. At the same time, the surface temperature T1 of the tension clamp is detected by the contact temperature sensor set on the fixture, and the ambient temperature T2 and ambient humidity H are detected by the ambient temperature and humidity sensor. S2: The constant current source module of the test host applies a preset test current I to the tension clamp, while the voltage sampling module collects the voltage drop U across the test part of the tension clamp through the voltage probe. S3: The main control unit calculates the measured resistance value R_meas=U / I of the tension clamp at the current temperature according to Ohm's law; S4: The main control unit acquires the material information of the tension clamp body and, based on the preset material temperature coefficient α, corrects the measured resistance value R_meas to the standard resistance value R0 at the standard reference temperature T0. The correction formula is: R0 = R_meas / [1 + α × (T1 - T0)]; Wherein, T0 is the preset standard reference temperature, T0=20℃, and α is the temperature coefficient of resistance of the tension clamp material near the standard reference temperature (20℃); S5: The main control unit packages the standard resistance value R0, the measured resistance value R_meas, the surface temperature of the tension clamp T1, the ambient temperature T2, the ambient humidity H, and the test current I data, and uploads them to the Internet of Things cloud platform through the wireless communication module. S6: The IoT cloud platform receives and stores test data, compares and analyzes the standard resistance value R0 with the historical test data and preset qualified threshold of the tension clamp, determines whether the conductivity of the tension clamp meets the requirements, and outputs operation and maintenance early warning information based on the data analysis results.

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