Double-end grounding loop resistance tester and method

Abstract

The invention discloses a double-end grounding loop resistance tester and method, and the tester comprises a current source loop which is composed of a to-be-tested resistor loop and a DC constant current source module, is connected with the two ends of the to-be-tested resistor loop in parallel, and generates voltage drop at the two ends of the to-be-tested resistor loop, the other end of the to-be-measured resistor loop is connected with one end of the voltage sampling circuit and one end of the direct current sampling circuit; the other end of the voltage sampling circuit and the other end of the direct current sampling circuit are connected with one end of the analog-to-digital conversion circuit; the other end of the analog-digital conversion circuit is connected with one end of the CPU circuit; and the other end of the CPU circuit is respectively connected with the display circuit, the storage circuit, the communication circuit and the key circuit. The current test probe is suitable for a large-diameter switch, the test precision and the operation simplicity can be guaranteed, and the technical problem that the shunt current of a grounding wire is difficult to test under different conditions can be solved.

Description

Technical Field

[0001] The invention belongs to the field of resistance testers, and in particular relates to a double-terminal ground loop resistance tester and a method. Background Art

[0002] The traditional method for measuring the loop resistance of GIS or GEBS / GCB switches is the DC voltage drop method. Its working principle is Ohm's law. A DC current is applied to the resistor to be measured. The test current applied is an automatic constant 100 ampere DC. The resistance value is calculated by measuring the voltage drop across the resistor. As early as the 1990s, someone proposed the vibration method test. The principle is that the current passing through the abnormal contact will produce vibration, and the contact contact is judged based on whether the voltage waveform is distorted. Other methods include partial discharge method, infrared temperature measurement method, SF6 gas detection method and light temperature measurement method, which can determine whether the contact has abnormal contact or poor contact to a certain extent.

[0003] At present, there is no mature equipment that can accurately detect the conductive loop resistance of GIS or GEBS / GCB switches without removing the grounding wire. The MOM600A microohmmeter developed by the Swedish Megger company can be used for the DC voltage drop method, but it is necessary to remove the grounding wire for measurement and modeling calculation. At present, there is no research on measuring the conductive loop resistance of GIS or GEBS / GCB without removing the grounding wire, and there are few reports on the calculation model and application of GIS or GEBS / GCB loops without removing the grounding wire. There is no precedent in China. Compared with foreign countries, domestic GIS or GEBS / GCB equipment started late, and the measurement method of conductive loop resistance was also measured with the help of foreign equipment using the DC voltage drop method. In the early GIS or GEBS / GCB equipment, the grounding knife lead conductor was connected to the shell. People also analyzed the resistance structure and used the DC voltage drop method to measure in batches to reverse the contact resistance value.

[0004] Therefore, the present invention aims to design a tester for quickly measuring the conductive loop resistance of GIS or GEBS / GCB without disassembling the grounding bar or pulling open the grounding switches at both ends. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a two-terminal ground loop resistance tester and method, which is suitable for current test probes of large diameter switches, can not only ensure the test accuracy and ease of operation, but also solve the technical problem of difficult shunt current testing of ground wires under different circumstances.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A two-terminal ground loop resistance tester, comprising a resistance loop to be tested, a DC constant current source module, a current source loop, a voltage sampling circuit, a DC current sampling circuit, an analog-to-digital conversion circuit, a CPU circuit, a display circuit, a storage circuit, a communication circuit and a key circuit; The current source loop is composed of a resistance loop to be measured and a DC constant current source module. The current source loop is connected in parallel with both ends of the resistance loop to be measured, and a voltage drop is generated at both ends of the resistance loop to be measured. The other end of the resistance loop to be measured is connected to one end of the voltage sampling circuit and one end of the DC current sampling circuit; The other end of the voltage sampling circuit and the other end of the DC current sampling circuit are both connected to one end of the analog-to-digital conversion circuit; The other end of the analog-to-digital conversion circuit is connected to one end of the CPU circuit; The other end of the CPU circuit is connected to the display circuit, the storage circuit, the communication circuit and the key circuit respectively. Preferably, the voltage sampling circuit is used to output a voltage signal; The DC current sampling circuit is used to output a DC current signal; The analog-to-digital conversion circuit is used to convert the detected voltage and DC current signals into digital signals; The CPU circuit is used to process the digital signal output by the analog-to-digital conversion circuit, and output the voltage value, current value and resistance value of the resistance loop to be measured; The storage circuit is used to store the measurement result output by the CPU circuit.

[0007] Preferably, the tester further comprises a Hall sensor, which is connected to a DC current sampling circuit for collecting DC signals.

[0008] Preferably, the tester further comprises a signal amplifier connected to the resistance loop to be tested, and the signal amplifier is used to amplify the voltage signal and the DC current signal.

[0009] Preferably, the tester further comprises a display, wherein the display circuit is arranged in the display, and the display is used to display the detected voltage value, current value and resistance value of the resistance loop to be measured.

[0010] Preferably, the tester further comprises a current program running module, the current program running module is connected to a key circuit, the key circuit is used to control the current program running module, and the current program running module is used to control the program flow and input parameters.

[0011] Preferably, the tester further comprises a host computer, the communication circuit is communicatively connected to the host computer, and the communication circuit is used to exchange data with the host computer and record historical measurement data.

[0012] Preferably, the Hall sensor includes a current probe, which is made of a flexible ferromagnetic material with high magnetic concentration capability; the flexible ferromagnetic material includes Permalloy, ferrite, silicon steel sheet and amorphous alloy, and the Permalloy contains copper or molybdenum elements.

[0013] Preferably, a probe core made of flexible ferromagnetic material is provided in the current probe, and the probe core includes a magnetic core composed of two semicircular rings, and a toothed bite structure is provided at the openings of the two semicircular rings, and the openings of the two semicircular rings are combined in a stacked bite manner.

[0014] Preferably, the diameter of the probe magnetic core is larger than its cross section, and the openings of the two semicircular rings are divided into an upper opening and a lower opening, and a Hall sensor chip is arranged at the upper opening.

[0015] A testing method for a two-terminal ground loop resistance tester comprises the following steps: Step 1: Connect the resistance circuit to be tested and the DC constant current source module: Step 1.1: Prepare the resistance circuit to be tested and the DC constant current source module; Step 1.2: Connect the resistance loop to be measured to the DC constant current source module to form a current source loop; Step 1.3: Ensure that the current source loop is connected in parallel with both ends of the resistance loop to be measured, and a voltage drop is generated across the resistance loop to be measured; Step 2: Connect the voltage sampling circuit and the DC current sampling circuit: Step 2.1: Connect one end of the voltage sampling circuit to one end of the resistance loop to be measured; Step 2.2: Connect one end of the DC current sampling circuit to the other end of the resistance loop to be measured; Step 2.3: Make sure that the other ends of the voltage sampling circuit and the DC current sampling circuit are connected to one end of the analog-to-digital conversion circuit; Step 3: Connect the analog-to-digital conversion circuit and the CPU circuit: Step 3.1: Connect the other end of the analog-to-digital conversion circuit to one end of the CPU circuit; Step 3.2: Ensure that the analog-to-digital conversion circuit can convert the detected voltage and DC current signals into digital signals and transmit them to the CPU circuit; Step 4: Connect the display circuit, storage circuit, communication circuit and key circuit: Step 4.1: Connect the other end of the CPU circuit to the display circuit, storage circuit, communication circuit and key circuit respectively; Step 4.2: Ensure that the display circuit can display the detected voltage value, current value and resistance value of the resistance loop to be measured; Step 4.3: Ensure that the storage circuit is capable of storing the measurement results output by the CPU circuit; Step 4.4: Ensure that the communication circuit can exchange data with the host computer and record the measurement history data; Step 4.5: Ensure that the key circuit can control the current program running module, thereby controlling the program flow and input parameters; Step 5: Start the tester: Step 5.1: Start the DC constant current source module to provide a stable DC current to the resistance circuit to be tested; Step 5.2: Detect the DC current signal of the resistance loop to be measured through the Hall sensor and the probe core made of flexible ferromagnetic material; Step 5.3: Detect the voltage drop signal at both ends of the resistance loop to be tested through the voltage sampling circuit; Step 6: Signal Amplification: Step 6.1: Transmitting the detected voltage signal and DC current signal to a signal amplifier; Step 6.2: Amplify the voltage signal and the DC current signal through a signal amplifier to improve the accuracy of the signal; Step 7: Analog to Digital Conversion: Step 7.1: Transmit the amplified voltage signal and DC current signal to an analog-to-digital conversion circuit; Step 7.2: The analog-to-digital conversion circuit converts the analog signal into a digital signal and transmits it to the CPU circuit; Step 8: Data Processing: Step 8.1: The CPU circuit processes the received digital signal and calculates the voltage value, current value and resistance value of the resistance loop to be measured; Step 8.2: The CPU circuit transmits the calculation result to the display circuit, the storage circuit and the communication circuit; Step 9: Result display and storage: Step 9.1: The display circuit displays the detected voltage value, current value and resistance value of the resistance loop to be measured; Step 9.2: The storage circuit stores the measurement results output by the CPU circuit for future viewing; Step 9.3: The communication circuit exchanges data with the host computer and records the test history data of the measured object; Step 10: End of testing: Step 10.1: Control the current program running module through the key circuit to stop the power supply of the DC constant current source module; Step 10.2: Disconnect all connections and turn off the tester.

[0016] The present invention can achieve the following beneficial effects: 1. The prior art usually uses a DC transformer to detect DC current, which transforms the DC current to be measured to meet the requirements of the automatic detection system. However, the DC transformer is large in size and expensive, which is not conducive to the low cost and miniaturization of the entire detection system. The present invention uses flexible ferromagnetic materials and Hall sensors to replace the traditional solution to manufacture a DC current measurement probe suitable for grounding buses of different structures. The probe core made of Hall effect and flexible ferromagnetic materials can be used according to different voltage levels and different types of grounding busbars. The probe is suitable for current testing probes of large diameter switches, which can not only ensure the test accuracy and ease of operation, but also solve the technical problem of difficult shunt current testing of grounding wires under different conditions.

[0017] 2. The present invention uses a lamination method to divide the Permalloy into two semicircular rings to form a probe core, and uses a lamination bite method to combine. The diameter of the probe core is larger than its cross section, which is suitable for measuring the current of the object to be measured in a narrow or flat space. The lamination bite method effectively avoids magnetic leakage, improves the magnetic induction intensity, and thus improves the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a connection diagram of the double-terminal ground loop resistance tester module of the present invention; Figure 2 It is a structural diagram of scheme 1 of the present invention; Figure 3 This is a structural diagram of Scheme 2 of the present invention; Figure 4 Structural diagram of Scheme 3 of the present invention; Figure 5 This is a structural diagram of Scheme 4 of the present invention.

[0019] In the figure: probe magnetic core 1, upper opening 2, lower opening 3, Hall sensor chip 4, and tooth-shaped bite structure 5. DETAILED DESCRIPTION

[0020] The preferred solution is Figures 1 to 5 As shown, a two-terminal ground loop resistance tester includes a resistance loop to be measured and a DC constant current source module, and also includes a current source loop, a voltage sampling circuit, a DC current sampling circuit, an analog-to-digital conversion circuit, a CPU circuit, a display circuit, a storage circuit, a communication circuit and a key circuit, wherein the current source loop is composed of a resistance loop to be measured and a DC constant current source module, the current source loop is connected in parallel with both ends of the resistance loop to be measured, and a voltage drop is generated at both ends of the resistance loop to be measured, and the other end of the resistance loop to be measured is connected to one end of the voltage sampling circuit and one end of the DC current sampling circuit; The other end of the voltage sampling circuit and the other end of the DC current sampling circuit are both connected to one end of the analog-to-digital conversion circuit; The other end of the analog-to-digital conversion circuit is connected to one end of the CPU circuit; The other end of the CPU circuit is connected to the display circuit, the storage circuit, the communication circuit and the key circuit respectively; Specifically, the voltage sampling circuit is used to output a voltage signal, the DC current sampling circuit is used to output a DC current signal, the analog-to-digital conversion circuit is used to convert the detected voltage and DC current signals into digital signals, the CPU circuit is used to process the digital signal output by the analog-to-digital conversion circuit, and output the voltage value, current value and resistance value of the resistance loop to be measured, the storage circuit is used to store the measurement results output by the CPU circuit, and also includes a Hall sensor, which is connected to the DC current sampling circuit for collecting DC signals.

[0021] Specifically, the present invention selects a Hall sensor produced by Asahi Kasei Corporation of Japan, the material of which is SbAs, the model is HW302B, which is a high-precision sensor chip.

[0022] Furthermore, the device also includes a signal amplifier connected to the resistance loop to be measured, and the signal amplifier is used to amplify the voltage signal and the DC current signal. With such a structural design, the signal amplified by the signal amplifier can be received more accurately by the analog-to-digital conversion circuit.

[0023] Furthermore, the device also includes a display, the display circuit is arranged in the display, and the display is used to display the detected voltage value, current value and resistance value of the resistance loop to be measured.

[0024] Furthermore, the device also includes a current program running module, which is connected to a key circuit, and the key circuit is used to control the current program running module, and the current program running module is used to control the program flow and input parameters.

[0025] Furthermore, the device also includes a host computer, and the communication circuit is communicatively connected to the host computer. The communication circuit is used to exchange data with the host computer and record measurement history data.

[0026] Furthermore, the Hall sensor includes a current probe, and the current probe is made of a flexible ferromagnetic material with high magnetic concentration ability.

[0027] Furthermore, the flexible ferromagnetic material includes permalloy, ferrite, silicon steel sheet and amorphous alloy, and copper or molybdenum elements are added to the permalloy.

[0028] Specifically, the present invention uses Permalloy as the manufacturing material of the probe magnetic core. The basic materials of Permalloy are iron and nickel, but in order to improve its performance, the manufacturer will add some other elements, such as copper, molybdenum, etc., which can not only improve the relative hardness of the material, but also reduce the eddy current after the laminated magnetic core is made, and increase the resistivity of the material. Due to the different proportions of elements, Permalloy is divided into four categories: 35%~40% Ni-Fe alloy, 45%~50% Ni-Fe alloy, 50%~65% Ni-Fe alloy and 70%~81% Ni-Fe alloy. These alloys can be used in different occasions due to the different proportions of elements.

[0029] Furthermore, a probe core made of flexible ferromagnetic material is provided in the current probe, and the probe core includes a core composed of two semicircular rings, and a toothed bite structure is provided at the openings of the two semicircular rings, and the openings of the two semicircular rings are combined in a stacked bite manner.

[0030] Furthermore, the diameter of the probe magnetic core is larger than its cross section, and the cross section is 6 mm. The openings of the two semicircular rings are divided into an upper opening and a lower opening, and a Hall sensor chip is arranged at the upper opening.

[0031] Furthermore, the outer radius of the semicircular ring of the probe magnetic core is 49 mm, and the inner radius of the semicircular ring of the probe magnetic core is 35 mm.

[0032] like Figure 1 As shown, the working principle of the two-terminal ground loop resistance tester based on large-diameter non-contact DC current measurement technology of the present invention is as follows: The resistance loop to be measured and the DC constant current source module form a current loop, and a voltage drop is generated at both ends of the resistance loop to be measured. Then, a DC clamp-type ammeter (or a probe core made of a Hall sensor and a flexible ferromagnetic material proposed in the present invention) is used to detect the current signal of the resistance loop to be measured respectively; then, the voltage drop signal at both ends of the resistance loop to be measured is transmitted to a signal amplifier for signal amplification; then, the detected voltage and DC current signals are transmitted to an analog-to-digital conversion circuit to be converted into digital signals, and finally, the CPU circuit processes the DC current and voltage signals to obtain the resistance value of the resistance loop to be measured.

[0033] Among them, the display circuits in the display all use universal liquid crystal display, and the display is used to display the detected voltage, current and resistance value; the key circuit is used to control the current program running module; the storage circuit is used to store the measurement results for viewing; the communication circuit is used to exchange data with the host computer to record the test history data of the measurement object; the communication circuit is used to exchange data with the host computer.

[0034] The prior art usually uses a DC transformer to detect DC current, which transforms the DC current to be measured to meet the requirements of the automatic detection system. However, the DC transformer is large in size and expensive, which is not conducive to the low cost and miniaturization of the entire detection system. The present invention uses flexible ferromagnetic materials and Hall sensors to replace the traditional solution to manufacture a DC current measurement probe suitable for grounding buses of different structures. The probe core made of Hall effect and flexible ferromagnetic materials can be used according to different voltage levels and different types of grounding busbars. The probe is suitable for current testing probes of large diameter switches, which can not only ensure the test accuracy and ease of operation, but also solve the technical problem of difficult shunt current testing of grounding wires under different conditions.

[0035] In addition, the present invention uses a lamination method to divide the Permalloy into two semicircular rings to form a probe core, and the laminations are combined in a bite-jointed manner. The diameter of the probe core is larger than its cross section, which is suitable for measuring the current of the object to be measured in a narrow or flat space, and the lamination bite-jointed manner effectively avoids magnetic leakage, improves the magnetic induction intensity, and thus improves the measurement accuracy. In addition, the two semicircular ring structures composed of the probe core are combined in a bite-jointed manner to measure the current on the conductive loop, and the voltage values ​​at both ends of the conductive loop are simultaneously measured, and the resistance value is calculated by Ohm's law.

[0036] Since the shape of the probe core is a critical part, several design options are available: Scenario 1: like Figure 2 As shown, Scheme 1 uses a winding method to divide the Permalloy into a magnetic core composed of two semicircular rings, and the Hall is placed in the air gap in the middle; and this magnetic core has a large caliber and a small cross-section, which is suitable for measuring the current of the object to be measured in a narrow or flat space, and the winding method is simple to make, low in production cost, and easy to mass produce. However, there is a certain gap at the position where the two semicircular rings are combined, which is called an air gap, and leakage magnetic field will occur. The larger the air gap, the more leakage magnetic field, the smaller the magnetic induction intensity, the greater the data difference, and the greater the error of the measured current. In addition, a Hall chip needs to be installed between the air gaps, resulting in the length of the air gap being at least 1mm (the thickness of the Hall chip is 1mm). This scheme will produce a very serious leakage magnetic phenomenon, reduce the magnetic induction intensity, and affect the measured results. Because the measured current of the present invention requires high precision, Scheme 1 is not applicable to the present invention.

[0037] Scenario 2: like Figure 3As shown, Scheme 2 uses a winding method to divide the Permalloy into a magnetic core consisting of a semicircle and two 1 / 4 rings, and the Hall is placed in the air gap between the two 1 / 4 rings; this magnetic core has a large diameter and a small cross-section, which is suitable for measuring the current of the object to be measured in a narrow or flat space. The winding method is used to divide a ring into three rings, which is easy to cause ring loss during the manufacturing process. At the same time, the enameled wire is easy to break during the winding process, which increases the difficulty and cost of the manufacturing process. In addition, Scheme 2 places a Hall sensor chip in the middle of the two 1 / 4 rings. This method effectively reduces the air gap, improves the magnetic induction intensity, and avoids serious magnetic leakage. There is still a certain air gap at the junction of the semicircle and the two 1 / 4 rings, which will also cause magnetic leakage. The accuracy is not very high, but this scheme is better than Scheme 1.

[0038] Solution 3: like Figure 4 As shown, Scheme 3 uses lamination to divide Permalloy into two semicircular rings to form a magnetic core, and the middle is biting, and the Hall is placed in the air gap in the middle; this magnetic core has a large diameter and a small cross-section, which is suitable for measuring the current of the object to be measured in a narrow or flat space. The lamination method is used, and the opening is made biting at the junction of the two semicircular rings (referred to as the opening), which effectively avoids magnetic leakage, improves the magnetic induction intensity, and improves the measurement accuracy. This method has a complex manufacturing process, high precision requirements for the lamination biting, and higher precision requirements for the installation of the magnetic core, which increases the manufacturing cost and lengthens the manufacturing cycle. The Hall sensor chip is placed at the upper opening, which produces a certain air gap, which will have a certain impact on the measurement accuracy. However, considering the measurement accuracy, this scheme is better than the previous two schemes.

[0039] Solution 4: like Figure 5 As shown, Scheme 4 uses lamination to divide Permalloy into a magnetic core consisting of a semicircular ring and two 1 / 4 circular rings, and the middle is biting, and the Hall is placed in the middle air gap between the two 1 / 4 circular rings; this magnetic core has a large diameter and a small cross-section, which is suitable for measuring the current of the object to be measured in a narrow or flat space. The lamination method is used, and the upper and lower openings are biting, which eliminates the air gap at the opening, improves the magnetic induction intensity, and improves the measurement accuracy. Scheme 4 has high requirements for the manufacturing process, the winding process of the magnetic core, and the installation of the magnetic core.

[0040] In summary, the present invention selects Scheme 3, which meets the characteristics of high precision and high sensitivity of the present invention, and the operation and production process of Scheme 3 is relatively simple, with high practicality and economic benefits.

[0041] The invention provides a test method for testing a double-terminal ground loop resistance, and the accurate measurement of the double-terminal ground loop resistance is achieved through the following steps.

[0042] Step 1: Connect the resistance circuit to be tested and the DC constant current source module: Step 1.1: Prepare the resistance circuit to be tested and the DC constant current source module.

[0043] Step 1.2: Connect the resistance loop to be measured to the DC constant current source module to form a current source loop.

[0044] Step 1.3: Ensure that the current source loop is connected in parallel with the resistor loop to be measured and a voltage drop is generated across the resistor loop to be measured.

[0045] Step 2: Connect the voltage sampling circuit and the DC current sampling circuit: Step 2.1: Connect one end of the voltage sampling circuit to one end of the resistance loop to be measured.

[0046] Step 2.2: Connect one end of the DC current sampling circuit to the other end of the resistance loop to be measured.

[0047] Step 2.3: Make sure that the other ends of the voltage sampling circuit and the DC current sampling circuit are connected to one end of the analog-to-digital conversion circuit.

[0048] Step 3: Connect the analog-to-digital conversion circuit and the CPU circuit: Step 3.1: Connect the other end of the analog-to-digital conversion circuit to one end of the CPU circuit.

[0049] Step 3.2: Ensure that the analog-to-digital conversion circuit can convert the detected voltage and DC current signals into digital signals and transmit them to the CPU circuit.

[0050] Step 4: Connect the display circuit, storage circuit, communication circuit and key circuit: Step 4.1: Connect the other end of the CPU circuit to the display circuit, storage circuit, communication circuit and key circuit respectively.

[0051] Step 4.2: Ensure that the display circuit can display the detected voltage value, current value and resistance value of the resistance loop to be measured.

[0052] Step 4.3: Ensure that the memory circuit is capable of storing the measurement results output by the CPU circuit.

[0053] Step 4.4: Ensure that the communication circuit can exchange data with the host computer and record the measurement history data.

[0054] Step 4.5: Ensure that the key circuit can control the current program running module, thereby controlling the program flow and input parameters.

[0055] Step 5: Start the tester: Step 5.1: Start the DC constant current source module to provide a stable DC current to the resistance circuit to be tested.

[0056] Step 5.2: Detect the DC current signal of the resistance loop to be measured through the Hall sensor and the probe core made of flexible ferromagnetic material.

[0057] Step 5.3: Detect the voltage drop signal across the resistance loop to be tested through the voltage sampling circuit.

[0058] Step 6: Signal Amplification: Step 6.1: Transmit the detected voltage signal and DC current signal to the signal amplifier.

[0059] Step 6.2: Amplify the voltage signal and the DC current signal through a signal amplifier to improve the accuracy of the signal.

[0060] Step 7: Analog to Digital Conversion: Step 7.1: Transmit the amplified voltage signal and DC current signal to the analog-to-digital conversion circuit.

[0061] Step 7.2: The analog-to-digital conversion circuit converts the analog signal into a digital signal and transmits it to the CPU circuit.

[0062] Step 8: Data Processing: Step 8.1: The CPU circuit processes the received digital signal and calculates the voltage value, current value and resistance value of the resistance loop to be measured.

[0063] Step 8.2: The CPU circuit transmits the calculation results to the display circuit, storage circuit and communication circuit.

[0064] Step 9: Result display and storage: Step 9.1: The display circuit displays the detected voltage value, current value and resistance value of the resistance loop to be measured.

[0065] Step 9.2: The storage circuit stores the measurement results output by the CPU circuit for future viewing.

[0066] Step 9.3: The communication circuit exchanges data with the host computer and records the test history data of the measured object.

[0067] Step 10: End of testing: Step 10.1: Control the current program running module through the key circuit to stop the power supply of the DC constant current source module.

[0068] Step 10.2: Disconnect all connections and turn off the tester.

[0069] This method ensures that the entire process from connection, signal acquisition, signal amplification, analog-to-digital conversion, data processing, result display and storage can be performed efficiently and accurately.

[0070] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A two-terminal ground loop resistance tester, characterized in that: It includes a resistance circuit to be tested, a DC constant current source module, a current source circuit, a voltage sampling circuit, a DC current sampling circuit, an analog-to-digital conversion circuit, a CPU circuit, a display circuit, a storage circuit, a communication circuit and a key circuit; The current source loop is composed of a resistance loop to be measured and a DC constant current source module. The current source loop is connected in parallel with both ends of the resistance loop to be measured, and a voltage drop is generated at both ends of the resistance loop to be measured. The other end of the resistance loop to be measured is connected to one end of the voltage sampling circuit and one end of the DC current sampling circuit; The other end of the voltage sampling circuit and the other end of the DC current sampling circuit are both connected to one end of the analog-to-digital conversion circuit; The other end of the analog-to-digital conversion circuit is connected to one end of the CPU circuit; The other end of the CPU circuit is connected to the display circuit, the storage circuit, the communication circuit and the key circuit respectively.

2. A two-terminal ground loop resistance tester according to claim 1, characterized in that: The voltage sampling circuit is used to output a voltage signal; The DC current sampling circuit is used to output a DC current signal; The analog-to-digital conversion circuit is used to convert the detected voltage and DC current signals into digital signals; The CPU circuit is used to process the digital signal output by the analog-to-digital conversion circuit, and output the voltage value, current value and resistance value of the resistance loop to be measured; The storage circuit is used to store the measurement result output by the CPU circuit.

3. A two-terminal ground loop resistance tester according to claim 1, characterized in that: It also includes a Hall sensor, which is connected to a DC current sampling circuit to collect DC signals.

4. A two-terminal ground loop resistance tester according to claim 1, characterized in that: It also includes a signal amplifier connected to the resistance loop to be measured, and the signal amplifier is used to amplify the voltage signal and the direct current signal.

5. A two-terminal ground loop resistance tester according to claim 1, characterized in that: It also includes a display, the display circuit is arranged in the display, and the display is used to display the detected voltage value, current value and resistance value of the resistance loop to be measured.

6. A two-terminal ground loop resistance tester according to claim 1, characterized in that: It also includes a current program running module, which is connected to a key circuit. The key circuit is used to control the current program running module, and the current program running module is used to control the program flow and input parameters.

7. A two-terminal ground loop resistance tester according to claim 1, characterized in that: It also includes a host computer, and the communication circuit is connected to the host computer for communication. The communication circuit is used to exchange data with the host computer and record measurement history data.

8. A two-terminal ground loop resistance tester according to claim 3, characterized in that: The Hall sensor comprises a current probe, which is made of a flexible ferromagnetic material with high magnetic concentration capability; the flexible ferromagnetic material comprises Permalloy, ferrite, silicon steel sheet and amorphous alloy, and the Permalloy is added with copper or molybdenum elements.

9. A two-terminal ground loop resistance tester according to claim 8, characterized in that: The current probe is provided with a probe core made of flexible ferromagnetic material. The probe core comprises a core composed of two semicircular rings. The openings of the two semicircular rings are provided with a toothed bite structure. The openings of the two semicircular rings are combined in a stacked bite manner.

10. A two-terminal ground loop resistance tester according to claim 9, characterized in that: The diameter of the probe magnetic core is larger than its cross section, and the openings of the two semicircular rings are divided into an upper opening and a lower opening, and a Hall sensor chip is arranged at the upper opening.

11. A testing method for a two-terminal ground loop resistance tester according to any one of claims 1 to 10, characterized in that The following steps are involved: Step 1: Connect the resistance circuit to be tested and the DC constant current source module: Step 1.1: Prepare the resistance circuit to be tested and the DC constant current source module; Step 1.2: Connect the resistance loop to be measured to the DC constant current source module to form a current source loop; Step 1.3: Ensure that the current source loop is connected in parallel with both ends of the resistance loop to be measured, and a voltage drop is generated across the resistance loop to be measured; Step 2: Connect the voltage sampling circuit and the DC current sampling circuit: Step 2.1: Connect one end of the voltage sampling circuit to one end of the resistance loop to be measured; Step 2.2: Connect one end of the DC current sampling circuit to the other end of the resistance loop to be measured; Step 2.3: Make sure that the other ends of the voltage sampling circuit and the DC current sampling circuit are connected to one end of the analog-to-digital conversion circuit; Step 3: Connect the analog-to-digital conversion circuit and the CPU circuit: Step 3.1: Connect the other end of the analog-to-digital conversion circuit to one end of the CPU circuit; Step 3.2: Ensure that the analog-to-digital conversion circuit can convert the detected voltage and DC current signals into digital signals and transmit them to the CPU circuit; Step 4: Connect the display circuit, storage circuit, communication circuit and key circuit: Step 4.1: Connect the other end of the CPU circuit to the display circuit, storage circuit, communication circuit and key circuit respectively; Step 4.2: Ensure that the display circuit can display the detected voltage value, current value and resistance value of the resistance loop to be measured; Step 4.3: Ensure that the storage circuit is capable of storing the measurement results output by the CPU circuit; Step 4.4: Ensure that the communication circuit can exchange data with the host computer and record the measurement history data; Step 4.5: Ensure that the key circuit can control the current program running module, thereby controlling the program flow and input parameters; Step 5: Start the tester: Step 5.1: Start the DC constant current source module to provide a stable DC current to the resistance circuit to be tested; Step 5.2: Detect the DC current signal of the resistance loop to be measured through the Hall sensor and the probe core made of flexible ferromagnetic material; Step 5.3: Detect the voltage drop signal at both ends of the resistance loop to be tested through the voltage sampling circuit; Step 6: Signal Amplification: Step 6.1: Transmitting the detected voltage signal and DC current signal to a signal amplifier; Step 6.2: Amplify the voltage signal and the DC current signal through a signal amplifier to improve the accuracy of the signal; Step 7: Analog to Digital Conversion: Step 7.1: Transmit the amplified voltage signal and DC current signal to an analog-to-digital conversion circuit; Step 7.2: The analog-to-digital conversion circuit converts the analog signal into a digital signal and transmits it to the CPU circuit; Step 8: Data Processing: Step 8.1: The CPU circuit processes the received digital signal and calculates the voltage value, current value and resistance value of the resistance loop to be measured; Step 8.2: The CPU circuit transmits the calculation result to the display circuit, the storage circuit and the communication circuit; Step 9: Result display and storage: Step 9.1: The display circuit displays the detected voltage value, current value and resistance value of the resistance loop to be measured; Step 9.2: The storage circuit stores the measurement results output by the CPU circuit for future viewing; Step 9.3: The communication circuit exchanges data with the host computer and records the test history data of the measured object; Step 10: End of testing: Step 10.1: Control the current program running module through the key circuit to stop the power supply of the DC constant current source module; Step 10.2: Disconnect all connections and turn off the tester.

Images