A three-phase switch loop resistance tester

Abstract

The application discloses a kind of measuring three-phase switch loop resistance tester, belong to electronic technology technical field.Mainly including acquisition processing module, low-voltage large-current power module and control on-off unit, low-voltage large-current power module provides stable DC power for acquisition processing module, acquisition processing module drives the power supply on-off of control on-off unit, acquisition processing module includes AD acquisition unit, processor, opto-coupler isolation module, by 0-200A adjustable stable large-current output, combined with high-precision AD acquisition and ohm law calculation, can accurately measure mΩ, μΩ level three-phase switch or cable loop resistance, adapt to the resistance characteristic difference of different electric power products, effectively verify whether it meets the specification requirements of national standard on contact resistance or loop resistance, solve the technical problem that different products need different current verification.

Description

Technical Field

[0001] This application relates to the field of electronic technology, specifically to a tester for measuring the resistance of a three-phase switch circuit. Background Technology

[0002] In the power sector, the contact resistance and loop resistance of three-phase high-voltage switches and high- and low-voltage cables need to be measured. The resistance of these user equipment is very small, measured in mΩ and μΩ. However, because these resistors generate heat under high current, causing energy loss, national standards have specific requirements for the contact resistance and loop resistance of these power products. Existing loop resistance tester equipment can help customers accurately test the contact resistance of three-phase switches or the loop resistance of cables, so as to help customers verify whether the contact resistance of their product switches or the loop resistance of their cables meet the requirements of national standards.

[0003] However, when accurately testing the three-phase contact resistance of high-voltage switches or the loop resistance of cables to help verify whether the contact resistance of the switches or the loop resistance of the cables are qualified and meet the requirements of national standards, different products have different contact resistances or loop resistances. To accurately measure them, different currents and times are required for verification. Utility Model Content

[0004] The purpose of this invention is to provide a three-phase switch circuit resistance tester to solve the problems mentioned in the background art.

[0005] The technical solution adopted by this application to solve its technical problem is: A three-phase switch circuit resistance tester includes an acquisition and processing module, a low-voltage high-current power supply module, and a control on / off unit. The low-voltage high-current power supply module provides a stable DC power supply to the acquisition and processing module, and the acquisition and processing module drives the power supply on / off of the control on / off unit. The acquisition and processing module includes an AD acquisition unit, a processor, and an optocoupler isolation module. The AD acquisition unit includes an AD1 acquisition unit and an AD2 acquisition unit. The AD1 acquisition unit acquires the voltage of the shunt resistor, and the AD2 acquisition unit acquires the voltage of the measured circuit resistance X. Both the AD1 acquisition unit and the AD2 acquisition unit are electrically isolated by the optocoupler isolation module and then transmit data through the SPI interface of the processor.

[0006] Preferably, the low-voltage high-current power supply module includes a 220V-DC conversion circuit and a constant current source. The 220V-DC conversion circuit converts the AC-220V input voltage of the mains power into DC power, which powers the acquisition and processing module and provides a constant current source of DC power, respectively.

[0007] Preferably, the shunt resistor is connected in series with the measured circuit resistor X, and the constant current source supplies power to the shunt resistor and the measured circuit resistor X.

[0008] Preferably, the control on / off unit includes relays, and the relays are provided in three groups, which are respectively connected to phase A, phase B, and phase C of the three-phase switch.

[0009] Preferably, the acquisition and processing module further includes a communication module, which includes a TTL-to-UDP module and a backup interface. The processor communicates with the host computer through the TTL-to-UDP module.

[0010] Preferably, the resistance X of the circuit under test is any one of the resistances of the three-phase switch or cable circuit to be tested.

[0011] The beneficial effects of this application are: 1. This technical solution uses a stable high current output adjustable from 0-200A, combined with high-precision AD acquisition and Ohm's law calculation, to accurately measure the resistance of three-phase switches or cable circuits at the mΩ and μΩ levels. It is adaptable to the differences in resistance characteristics of different power products, effectively verifying whether they meet the national standard requirements for contact resistance or circuit resistance, and solving the technical problem of different products requiring different currents for verification.

[0012] 2. The device adopts an optical isolation design to achieve isolation between strong and weak electrical signals, which greatly improves the measurement anti-interference capability and data accuracy. It is also equipped with multiple communication interfaces such as TTL to UDP module, 485, and spare RS232, which not only meet the requirements of efficient data interaction with the host computer, but also reserve space for functional expansion, thereby improving the practicality and scenario adaptability of the device.

[0013] In addition to the purposes, features, and advantages described above, this application has other purposes, features, and advantages. A further detailed description of this application will be provided below with reference to the figures. Attached Figure Description

[0014] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a system block diagram of a three-phase switch circuit resistance measuring instrument according to the present invention. Detailed Implementation

[0015] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0016] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application.

[0017] Please see Figure 1 The embodiments provided by this utility model are as follows: A three-phase switch circuit resistance tester includes an acquisition and processing module, a low-voltage high-current power supply module, and a control on / off unit. The low-voltage high-current power supply module provides a stable DC power supply to the acquisition and processing module. The low-voltage high-current power supply module includes a 220V-DC conversion circuit and a constant current source. The 220V-DC conversion circuit converts the AC-220V input voltage of the mains power into DC power, which powers the acquisition and processing module and provides a constant current source of DC power. The acquisition and processing module drives the power supply to the on / off unit. The acquisition and processing module includes an AD acquisition unit, a processor, and an optocoupler isolation module. The shunt resistor and the measured circuit resistance X are connected in series. A constant current source supplies power to the shunt resistor and the measured circuit resistance X. The AD acquisition unit includes AD1 acquisition unit and AD2 acquisition unit. AD1 acquisition unit acquires the voltage of the shunt resistor and calculates the circuit current. AD2 acquisition unit acquires the voltage of the measured circuit resistance X and calculates the resistance voltage drop. Both AD1 and AD2 acquisition units are electrically isolated by the optocoupler isolation module and transmit data through the processor's SPI interface. The processor core control unit interacts with the optocoupler isolation module through the SPI1 and SPI2 interfaces to achieve signal isolation transmission and command control, and simultaneously completes resistance calculation, relay control, and data interaction. The processor can be a TM32F103RCT6 or an STM32F407VET6.

[0018] The optocoupler isolation module employs an optocoupler. During operation, the input electrical signal drives the light source to emit light. The receiver receives the light signal and converts it into an electrical signal, which is then output from the output. This achieves electrical-to-optical-to-electrical signal conversion, thus realizing electrical isolation between the high-voltage circuit (high-current, high-voltage section) and the low-voltage circuit (acquisition, processing, and control section). This prevents interference signals from the high-current circuit from entering the acquisition and processing module, ensuring the accuracy of the voltage signal acquired by the AD converter and guaranteeing the accuracy of resistance calculations. Furthermore, it avoids damage to the low-voltage circuit from high-voltage power, improving the system's stability and safety. The resistance X of the circuit to be tested can be any one of the resistance of the three-phase switch or the cable circuit to be tested. The acquisition and processing module also includes a communication module, which includes a TTL to UDP module and a spare interface. The processor communicates with the host computer through the TTL to UDP module. The control unit includes relays, and there are three sets of relays. The three sets of relays are respectively connected to the A, B and C phases of the three-phase switch. During operation, the host computer sends measurement commands to the processor via a TTL-to-UDP module. The processor controls the relay to connect the target phase circuits of phases A, B, and C according to the commands. The acquisition and processing module outputs a 0-5V analog voltage, and the constant current source of the low-voltage high-current power supply module outputs a stable current of 0-200A accordingly. The current loop is: constant current source positive terminal → shunt resistor → measured circuit resistance X → constant current source negative terminal, forming a closed high-current loop.

[0019] The AD1 acquisition unit acquires the voltage across the shunt resistor, converts it into a digital value, and transmits it to the processor via optocoupler isolation and SPI interface. The processor calculates the loop current using Ohm's law. The AD2 acquisition unit acquires the voltage across the measured loop resistor X, converts and isolates it, and transmits it to the processor to obtain the voltage drop across the resistor. The processor calculates the measured loop resistance value using Ohm's law and uploads the result to the host computer via the TTL to UDP module.

[0020] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A tester for measuring the resistance of a three-phase switch circuit, characterized in that: It includes a data acquisition and processing module, a low-voltage high-current power supply module, and a control on / off unit. The low-voltage high-current power supply module provides a stable DC power supply to the data acquisition and processing module, and the data acquisition and processing module drives the power supply of the control on / off unit to switch on and off. The acquisition and processing module includes an AD acquisition unit, a processor, and an optocoupler isolation module. The AD acquisition unit includes an AD1 acquisition unit and an AD2 acquisition unit. The AD1 acquisition unit acquires the voltage of the shunt resistor, and the AD2 acquisition unit acquires the voltage of the measured circuit resistance X. Both the AD1 acquisition unit and the AD2 acquisition unit are electrically isolated by the optocoupler isolation module and then transmit data through the SPI interface of the processor.

2. The three-phase switch circuit resistance measuring instrument according to claim 1, characterized in that: The low-voltage, high-current power supply module includes a 220V-DC conversion circuit and a constant current source. The 220V-DC conversion circuit converts the AC-220V input voltage of the mains power into DC power, which powers the acquisition and processing module and provides a constant current source of DC power.

3. The three-phase switch circuit resistance measuring instrument according to claim 2, characterized in that: The shunt resistor is connected in series with the measured circuit resistance X, and the constant current source supplies power to the shunt resistor and the measured circuit resistance X.

4. The three-phase switch circuit resistance measuring instrument according to claim 1, characterized in that: The control unit includes relays, and there are three sets of relays. The three sets of relays are respectively connected to phase A, phase B, and phase C of the three-phase switch.

5. The three-phase switch circuit resistance measuring instrument according to claim 1, characterized in that: The acquisition and processing module also includes a communication module, which includes a TTL-to-UDP module and a backup interface. The processor communicates with the host computer through the TTL-to-UDP module.

6. The three-phase switch circuit resistance measuring instrument according to claim 1, characterized in that: The resistance X of the circuit under test can be any one of the resistances of the three-phase switch or cable circuit to be tested.

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