Circuit and device for detecting virtual connection of grounding wire

Abstract

The utility model discloses a circuit and a device for detecting virtual connection of a grounding wire, and belongs to the technical field of resistance detection. According to the circuit for detecting virtual connection of the ground wire, the operational amplifier and the triode form a negative feedback loop, so that the current flowing through the load to be detected is kept constant, the ground resistance value can be accurately calculated by measuring the voltage drop, the detection precision is high, and the problem of traditional virtual connection detection of the ground wire can be effectively solved; therefore, the problem of poor contact caused by steel rail corrosion, smudginess or bolt looseness can be found in time, and the electric shock risk of operators can be effectively prevented. By adopting the combined design of the integrated operational amplifier and the triode, the circuit structure is simple and reliable, the anti-interference capability is strong, and the circuit is suitable for complex and severe field environments of ordinary speed railways.

Description

Technical Field

[0001] This utility model relates to the field of resistance detection technology, specifically to a circuit and device for detecting loose connections in grounding wires. Background Technology

[0002] In the maintenance of overhead contact lines during power outages on conventional railways, the grounding wire is a crucial safety device to prevent electric shock to workers, and its electrical reliability directly affects operational safety. Existing overhead contact line grounding wires are divided into upper and lower grounding wires based on their installation location: the upper grounding wire connects the overhead equipment to the conductor via a special hook; the lower grounding wire is equipped with a hook-shaped grounding shoe and is physically connected to the rail base or steel column angle steel, etc., using bolt fastening. The cross-sectional area of ​​the upper and lower grounding wires is not less than 25mm². 2 A complete electrical circuit is formed by a copper flexible wire approximately 6m in length.

[0003] Due to the complex operating environment of conventional railways, the rail surface often has layers of contamination such as rust and oil. In actual operation, if the workers do not thoroughly treat the rail contact surface or the tightening torque does not meet the specifications, it is very easy for a loose connection defect to form between the grounding shoe and the rail contact surface. This defect will significantly increase the contact resistance value, causing the grounding impedance to exceed the safety threshold, obstructing the discharge path of induced current, and exposing workers to the risk of electric shock. Existing grounding wire detection technology has the following limitations: First, anti-misoperation devices can only ensure the mechanical connection status and cannot detect the electrical connection quality in real time; second, traditional multimeter testing methods are highly dependent on manual operation and lack sensitivity to microscopic defects on the contact surface. These technical defects make it difficult for existing methods to effectively detect loose grounding wire faults, creating safety hazards in overhead contact line maintenance operations.

[0004] Therefore, how to provide a circuit for detecting loose grounding wires and provide reliable safety assurance for overhead contact line maintenance has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a circuit and device for detecting loose grounding wire connections, so as to overcome the problem that it is difficult to effectively detect loose grounding wire connection faults in the prior art.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution:

[0007] A circuit for detecting a loose grounding connection includes a first resistor R2, a second resistor R3, a third resistor R4, a load under test RL, an integrated operational amplifier U4, a transistor Q2, and a power supply VCC.

[0008] The output of the integrated operational amplifier U4 is connected to the base of the transistor Q2. The emitter of the transistor Q2 is divided into two paths: the first path is connected to the inverting input of the integrated operational amplifier U4, and the second path is connected to the third resistor R4. The third resistor R4 is divided into two paths: the first path is connected to the second resistor R3, and the second path is grounded. The second resistor R3 is divided into two paths: the first path is connected to the non-inverting input of the integrated operational amplifier U4, and the second path is divided into two paths via the first resistor R2: the first path is connected to the collector of the transistor Q2 via the load under test RL, and the second path is connected to the power supply VCC.

[0009] A further improvement of this invention is that transistor Q2 is an NPN transistor.

[0010] A further improvement of this utility model is that the power supply VCC is a DC power supply, and the voltage of the DC power supply is +5V.

[0011] A further improvement of this invention is that the resistance value of the second resistor R3 is equal to the resistance value of the third resistor R4, and the resistance value of the first resistor R2 is greater than the resistance value of the second resistor R3.

[0012] This utility model also provides a device for detecting a loose connection in a grounding wire, including the circuit for detecting a loose connection in a grounding wire as described above, an analog-to-digital converter module, a microcontroller module, an audible and visual alarm module, and a voltage regulator module; the voltage regulator module is used to output a +5V power supply VCC;

[0013] The load under test RL is divided into two paths. The first path is connected to the collector of transistor Q2. The second path is connected to the first port of the microcontroller module via the analog-to-digital converter module. The second port of the microcontroller module is connected to the sound and light alarm module.

[0014] A further improvement of this utility model is that it also includes a power-off protection module, which is connected to the third port of the microcontroller module.

[0015] A further improvement of this utility model is that the sound and light alarm module includes a first module and a second module;

[0016] The first module includes a fourth resistor R5, a transistor Q1, and a buzzer LS1. One end of the fourth resistor R5 is connected to the base of the transistor Q1, the collector of the transistor Q1 is connected to the power supply VCC, and the emitter of the transistor Q1 is grounded through the buzzer LS1. The other end of the fourth resistor R5 is connected to the microcontroller module.

[0017] The second module includes a first light-emitting diode D1, a second light-emitting diode D2, a fifth resistor R6, and a sixth resistor R7. The microcontroller module is connected to the cathodes of the first light-emitting diode D1 and the second light-emitting diode D2, respectively. The anode of the first light-emitting diode D1 is connected to the power supply VCC via the fifth resistor R6, and the anode of the second light-emitting diode D2 is connected to the power supply VCC via the sixth resistor R7.

[0018] A further improvement of this invention is that transistor Q1 is a PNP type transistor.

[0019] A further improvement of this invention is that the resistance values ​​of the fourth resistor R5, the fifth resistor R6, and the sixth resistor R7 are equal.

[0020] The further improvements of this utility model are as follows: the microcontroller module uses a chip of model STC89C52; the analog-to-digital converter module uses a chip of model ADC0832; the power-down protection module uses a chip of model 24C02; the voltage regulator module uses a chip of model LM7805CT; and the integrated operational amplifier U4 uses an operational amplifier of model LM358.

[0021] Compared with the prior art, the positive and progressive effects of this utility model are as follows:

[0022] The circuit provided by this utility model for detecting loose grounding wire connections utilizes an operational amplifier U4 and a transistor Q2 to form a negative feedback loop, keeping the current flowing through the load RL under test constant. By measuring the voltage drop, the grounding resistance value can be accurately calculated, resulting in high detection accuracy. This effectively solves the traditional problem of detecting loose grounding wire connections, thereby promptly identifying poor contact caused by rail corrosion, dirt, or loose bolts, and effectively preventing the risk of electric shock to workers. Through the combination design of integrated operational amplifier and transistor, the circuit structure is simple and reliable, with strong anti-interference ability, and is suitable for the complex and harsh field environment of conventional railways.

[0023] The device for detecting loose grounding wire connections provided by this utility model uses a constant current source circuit to ensure that the measurement results are not affected by power supply voltage fluctuations, thus guaranteeing the stability and reliability of the detection and providing a safety guarantee for overhead contact line maintenance operations. This device can be integrated into portable testing equipment, is small in size and light in weight, and can be used handheld, making it convenient for on-site operators to quickly judge the grounding wire connection quality, thereby improving the safety and work efficiency of overhead contact line maintenance operations. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the present invention and constitute a part of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0025] Figure 1 This is a circuit diagram of the present invention for detecting a loose connection in a grounding wire;

[0026] Figure 2 This is a connection diagram of the analog-to-digital conversion module in Embodiment 1 of this utility model;

[0027] Figure 3 This is a connection diagram of the power failure protection module in Embodiment 1 of this utility model;

[0028] Figure 4 This is a connection diagram of the microcontroller module in Embodiment 1 of this utility model;

[0029] Figure 5 This is a connection diagram of the second module in Embodiment 1 of this utility model;

[0030] Figure 6 This is a connection diagram of the first module in Embodiment 1 of this utility model;

[0031] Figure 7 This is a schematic diagram of the circuit board structure of a device for detecting loose grounding wires according to the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0034] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0035] In the description of the embodiments of this utility model, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use, they are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the utility model. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0036] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0037] In the description of the embodiments of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0038] The present invention will be further described in detail below with reference to the accompanying drawings. The description is intended to explain the present invention and not to limit it.

[0039] A circuit for detecting a loose grounding connection includes a first resistor R2, a second resistor R3, a third resistor R4, a load under test RL, an integrated operational amplifier U4, a transistor Q2, and a power supply VCC.

[0040] The output of the integrated operational amplifier U4 is connected to the base of the transistor Q2. The emitter of the transistor Q2 is divided into two paths: the first path is connected to the inverting input of the integrated operational amplifier U4, and the second path is connected to the third resistor R4. The third resistor R4 is divided into two paths: the first path is connected to the second resistor R3, and the second path is grounded. The second resistor R3 is divided into two paths: the first path is connected to the non-inverting input of the integrated operational amplifier U4, and the second path is divided into two paths via the first resistor R2: the first path is connected to the collector of the transistor Q2 via the load under test RL, and the second path is connected to the power supply VCC.

[0041] The circuit provided by this utility model for detecting loose grounding wire connections utilizes an operational amplifier U4 and a transistor Q2 to form a negative feedback loop, keeping the current flowing through the load RL under test constant. By measuring the voltage drop, the grounding resistance value can be accurately calculated, resulting in high detection accuracy. This effectively solves the traditional problem of detecting loose grounding wire connections, thereby promptly identifying poor contact caused by rail corrosion, dirt, or loose bolts, and effectively preventing the risk of electric shock to workers. Through the combination design of integrated operational amplifier and transistor, the circuit structure is simple and reliable, with strong anti-interference ability, and is suitable for the complex and harsh field environment of conventional railways.

[0042] See Figure 1 Operational amplifier U4 operates in the linear region, and transistor Q2 operates in the amplification region. The potentials at the non-inverting input, inverting input, and output of operational amplifier U4 are u0, u1, u2, u3, u4 ...5, u6, u7< / + u - u o Among them, the potentials of the non-inverting input, inverting input, and output terminals of operational amplifier U4 are u, respectively. + u - u o The base current of transistor Q2 is I. b The current across the load RL under test is I. L The voltage and current across the third resistor R4 are U and U, respectively. R4 I R4 .

[0043] Based on the properties of operational amplifiers, circuit topology, and Ohm's law, we have I R4 =U R4 / R4=u - / R4; Based on the properties of the transistor: I L ≈I R4 Therefore, we can conclude that:

[0044] When I L When I ↗ R4 ↗→U R4 ↗→u - ↗→(u + -u - )↘→u o ↘→I b ↘→I L ↘.

[0045] When I L When ↘, I R4 ↘→U R4 ↘→u - ↘→(u + -u - )↗→u o ↗→I b ↗→IL ↗.

[0046] In this context, ↗ represents increasing, ↘ represents decreasing, and → represents a progressive relationship.

[0047] Specifically, when the load under test RL is connected to the circuit, the detection device starts working, and at this time the current flowing through the load under test RL is I. L The response process is as follows (duration less than 1 millisecond): If I L Increase, because transistor Q2 operates in the amplification region, according to its properties we have I L ≈I R4 , then I R4 Increase; according to Ohm's law U R4 =I R4 ·R4, then U R4 Increase; according to the properties of operational amplifiers, then u - =U R4 Increase, (u + -u - Decrease, u o Decrease, I b Decrease; since transistor Q2 is operating in the amplification region, I L Decrease; if I L The value decreases because transistor Q2 operates in the amplification region, and according to its properties, I... L ≈I R4 , then I R4 Decrease; according to Ohm's law U R4 =I R4 ·R4, then U R4 Decrease; according to the properties of operational amplifiers, then u - =U R4 Decrease, (u + -u - Increase, u o Increase, I b Increase; since transistor Q2 is operating in the amplification region, then I L Therefore, the circuit provided by this invention for detecting loose grounding wires can introduce a negative feedback mechanism, making the current on the load RL under test constant.

[0048] Specifically, transistor Q2 is an NPN transistor.

[0049] Specifically, the power supply VCC is a DC power supply, and the voltage of the DC power supply is +5V.

[0050] Specifically, the resistance of the second resistor R3 is equal to the resistance of the third resistor R4, and the resistance of the first resistor R2 is greater than the resistance of the second resistor R3.

[0051] Based on the same inventive concept, this utility model also provides a device for detecting a loose connection in a grounding wire, including the circuit for detecting a loose connection in a grounding wire as described above, an analog-to-digital converter module, a microcontroller module, an audible and visual alarm module, and a voltage regulator module; the voltage regulator module is used to output a +5V power supply VCC;

[0052] The load under test RL is divided into two paths. The first path is connected to the collector of transistor Q2. The second path is connected to the first port of the microcontroller module via the analog-to-digital converter module. The second port of the microcontroller module is connected to the sound and light alarm module.

[0053] The device for detecting loose grounding wire connections provided by this utility model uses a constant current source circuit to ensure that the measurement results are not affected by power supply voltage fluctuations, thus guaranteeing the stability and reliability of the detection and providing a safety guarantee for overhead contact line maintenance operations. This device can be integrated into portable testing equipment, is small in size and light in weight, and can be used handheld, making it convenient for on-site operators to quickly judge the grounding wire connection quality, thereby improving the safety and work efficiency of overhead contact line maintenance operations.

[0054] Specifically, it also includes a power-down protection module, which is connected to the third port of the microcontroller module.

[0055] Specifically, the audible and visual alarm module includes a first module and a second module;

[0056] The first module includes a fourth resistor R5, a transistor Q1, and a buzzer LS1. One end of the fourth resistor R5 is connected to the base of the transistor Q1, the collector of the transistor Q1 is connected to the power supply VCC, and the emitter of the transistor Q1 is grounded through the buzzer LS1. The other end of the fourth resistor R5 is connected to the microcontroller module.

[0057] The second module includes a first light-emitting diode D1, a second light-emitting diode D2, a fifth resistor R6, and a sixth resistor R7. The microcontroller module is connected to the cathodes of the first light-emitting diode D1 and the second light-emitting diode D2, respectively. The anode of the first light-emitting diode D1 is connected to the power supply VCC via the fifth resistor R6, and the anode of the second light-emitting diode D2 is connected to the power supply VCC via the sixth resistor R7.

[0058] Specifically, transistor Q1 is a PNP type transistor.

[0059] Specifically, the resistance values ​​of the fourth resistor R5, the fifth resistor R6, and the sixth resistor R7 are equal.

[0060] Specifically, the microcontroller module uses the STC89C52 chip; the analog-to-digital converter module uses the ADC0832 chip; the power-down protection module uses the 24C02 chip; the regulated power supply module uses the LM7805CT chip; and the integrated operational amplifier U4 uses the LM358 operational amplifier.

[0061] Example 1

[0062] A device for detecting a loose grounding wire connection includes the circuit described above for detecting a loose grounding wire connection, an analog-to-digital converter module, a microcontroller module, an audible and visual alarm module, and a regulated power supply module; the regulated power supply module is used to output a +5V power supply VCC.

[0063] The microcontroller module uses the STC89C52 chip; the analog-to-digital converter module uses the ADC0832 chip; the power-down protection module uses the 24C02 chip; the voltage regulator module uses the LM7805CT chip; and the integrated operational amplifier U4 uses the LM358 operational amplifier.

[0064] See Figure 2 The power supply terminal P1, A9, is connected to the Vin terminal of the LM7805 chip U6; the positive terminal of capacitor C4 is connected to the Vin terminal of the LM7805 chip U6, and the negative terminal of capacitor C4 is connected to the GND terminal of the LM7805 chip U6; capacitor C5 is connected between the Vin and GND terminals of the LM7805 chip U6; the positive terminal of capacitor C6 is connected to the Vout terminal of the LM7805 chip U6, and the negative terminal is connected to the GND terminal of the LM7805 chip U6; capacitor C7 is connected to the LM7805 chip... Between the Vout and GND terminals of chip U6; the B12 terminal of power terminal P1 is connected to the GND terminal of LM7805 chip U6, which is the common ground terminal of the device used to detect loose grounding; the power supply VCC is led out from the Vout terminal of LM7805 chip U6 and is the common power supply terminal of the device used to detect loose grounding. This part is based on the LM7805 chip and is used to output a stable +5V power supply voltage at the Vout terminal of LM7805 chip U6.

[0065] See Figure 3 The SDA pin of the 24C02 chip U3 is connected to the P31 pin of the STC89C52 microcontroller U1, the SCK pin of the 24C02 chip U3 is connected to the P30 pin of the STC89C52 microcontroller U1, the WP, A1, A2, A0, and GND pins of the 24C02 chip U3 are connected to the common ground, and the VCC pin of the 24C02 chip U3 is connected to the common power supply. This part, with the 24C02 chip as the core, provides power-loss protection for the microcontroller data.

[0066] See Figure 4 The VCC and EA terminals of the STC89C52 microcontroller U1 are connected to the common power supply terminal; capacitor C1 and push-button switch S1 are connected between the common power supply terminal and the RST terminal of the STC89C52 microcontroller U1; resistor R1 is connected between the RST terminal and the GND terminal of the STC89C52 microcontroller U1; crystal oscillator Y1 is connected between XTAL1 and XTAL2 of the STC89C52 microcontroller U1; capacitor C2 is connected between XTAL2 and GND of the STC89C52 microcontroller U1; capacitor C3 is connected between XTAL1 and the common ground terminal of the STC89C52 microcontroller U1. Pin 8 of the LM358 operational amplifier chip U4 is connected to the common power supply, pin 4 is connected to the common ground, and pin 1 is connected to the base of transistor Q2. Measurement terminal P2 is a two-pin terminal block, serving as the interface for the load under test. Pin 1 of measurement terminal P2 is connected to the common power supply, and pin 3 is connected to the collector of NPN transistor Q2. Resistor R2 is connected between the common power supply and pin 3 of the LM358 operational amplifier chip U4. Resistor R3 is connected between pin 3 of the LM358 operational amplifier chip U4 and the common ground. Resistor R4 is connected between the emitter of NPN transistor Q2 and the common ground. The CH0 pin of the ADC0832 chip U2 is connected to the base of NPN transistor Q2. The collector of ADC0832 chip U2 is connected to P2.3 of STC89C52 microcontroller U1, the DI terminal of ADC0832 chip U2 is connected to P2.4 of STC89C52 microcontroller U1, the CS terminal of ADC0832 chip U2 is connected to P2.5 of STC89C52 microcontroller U1, the CLK terminal of ADC0832 chip U2 is connected to P2.6 of STC89C52 microcontroller U1, the VCC terminal of ADC0832 chip U2 is connected to the common power supply terminal, and the GND terminal of ADC0832 chip U2 is connected to the common ground terminal. This part uses the integrated operational amplifier LM358 chip U4 and NPN transistor Q2 as the core to generate a constant current on the load under test. ADC0832 chip U2 collects the voltage signal on the ground side of the load under test, performs analog-to-digital conversion, and sends it to STC89C52 microcontroller U1.

[0067] See Figure 5 and Figure 6The fifth resistor R6 is connected between the anode of LED D1 and the common power supply terminal; the sixth resistor R7 is connected between the anode of LED D2 and the common power supply terminal; the cathode of LED D1 is connected to P3.5 of STC89C52 microcontroller U1; the cathode of LED D2 is connected to P3.7 of STC89C52 microcontroller U1; the collector of PNP transistor Q1 is connected to the common power supply terminal; resistor R5 is connected between P3.4 of STC89C52 microcontroller U1 and the base of Q1; the buzzer LS1 is connected between the emitter of PNP transistor Q1 and the common ground terminal. This part consists of LEDs and a buzzer, and the alarm is controlled by the P3.4, P3.5, and P3.7 pins of STC89C52 microcontroller U1.

[0068] See Figure 7 This is a schematic diagram of the circuit board structure of this utility model. All component numbers are shown in Table 1. The overall length of the circuit board is 60mm, the width is 60mm, the height is 11mm, and the weight does not exceed 100g.

[0069] Table 1 Component List

[0070]

[0071]

[0072] The above-mentioned device is used to test the load under test. The load resistance R measured at the connection between the lower grounding wire of the contact wire and the rail is... L When R is 8Ω L When the circuit is connected between terminals 1 and 3 of P2, it begins to operate. Within milliseconds, under the negative feedback mechanism formed by the integrated operational amplifier U4 and transistor Q2, the load current remains constant at I. L =VCC·R3 / [R4(R2+R3)]=4mA, R L The ground side is the voltage U acquired by the ADC0832. m =32mV, the analog voltage acquired by the ADC0832 from the CH0 terminal is converted from analog to digital and then sent to the P2.3 terminal of the microcontroller through the DO terminal. The microcontroller receives U m The sampled voltage is 32mV. Since it is a constant current source under the negative feedback mechanism, I... L Given that R is calculated L =U m / I L =8Ω, less than the set threshold U f=10Ω, therefore the requirement is met, and no alarm is triggered. Therefore, the microcontroller outputs a low level at P3.5, while P3.7 and P3.4 remain high. The green LED D1 cathode emits green light due to the low level at P3.5, while the red LED D2 does not emit light because there is no voltage difference at the high level at P3.7. The buzzer does not sound because the high level at P3.4 prevents Q1 from conducting. This indicates that the lower ground connection is reliable.

[0073] The load resistance R measured at the connection point between the lower grounding wire of the contact wire and the rail. L When R is 100Ω, L When the circuit is connected between terminals 1 and 3 of P2, it begins to operate. Within milliseconds, under the negative feedback mechanism formed by the integrated operational amplifier U4 and transistor Q2, the load current remains constant at I. L =VCC·R3 / [R4(R2+R3)]=4mA, R L The ground side is the voltage U acquired by the ADC0832. m =400mV. The analog voltage acquired by the ADC0832 from the CH0 terminal is converted from analog to digital and then sent to the P2.3 terminal of the microcontroller through the DO terminal; the microcontroller receives U m The sampling voltage is 400mV. Because it is a constant current source under the negative feedback mechanism, I... L Given that R is calculated L =U m / I L =100Ω, greater than the set threshold U f =10Ω, therefore it does not meet the requirements and an alarm needs to be triggered; therefore, the microcontroller outputs a high level at P3.5 and a low level at P3.7 and P3.4; then the green LED D1 cathode does not light up because the high level at P3.5 does not conduct, the red LED D2 conducts due to the voltage difference at P3.7 and emits red light, and the buzzer emits a buzzing sound because the low level at P3.4 Q1 conducts. At this time, it indicates that the lower ground wire is loosely connected.

[0074] This device integrates all modules onto a single circuit board, resulting in a small overall size, low cost, and portability, making it suitable for mobile operations and highly targeted at overhead contact line grounding work. It utilizes an integrated operational amplifier and transistor-based negative feedback circuit to form a constant current source, ensuring a constant and known load current. The ADC0832 analog-to-digital converter chip acquires the load grounding voltage, thus measuring the resistance parameters. The constant current source circuit is simple in structure and requires few components. The ADC0832 chip offers high accuracy and fast response, enabling more convenient and rapid measurement of the resistance parameters at the lower grounding wire connection. The device employs a microcontroller for logical judgment, combined with LEDs and a buzzer for audible and visual alarms. Upon receiving the resistance parameters at the lower grounding wire connection, it quickly identifies loose connections and triggers audible and visual alarms, providing a faster and more efficient assessment compared to manual reading and judgment.

[0075] Finally, it should be noted that the embodiments listed above are merely one or more specific manifestations of the technical solution of this utility model. Their purpose is to clearly illustrate the concept, principle, and application of this utility model through specific examples, and is by no means intended to limit the scope of protection of this utility model to these specific embodiments. In fact, the true value of this utility model lies in its proposed technical ideas and innovations, rather than its manifestations or implementation methods.

[0076] For those skilled in the art, after thoroughly reading and understanding the technical solution of this utility model, they are fully capable of making various changes, modifications, or equivalent substitutions to the specific embodiments of the utility model based on their own professional knowledge and skills. These changes may include, but are not limited to: adjusting the range of technical parameters, optimizing the algorithm flow to improve efficiency, and replacing some technical components to achieve better compatibility or reduce costs. As long as these modified technical solutions substantially retain the technical features claimed by the original utility model, that is, they can still achieve the core functions and effects of this utility model, then these changes should be considered to fall within the scope of protection of the pending claims of this utility model.

[0077] Furthermore, with the continuous progress and development of technology, new technical means and methods are constantly emerging, which provides ample space for the further improvement and perfection of this utility model. Therefore, the scope of protection of this utility model should also include reasonable and foresightful improvements and extensions based on existing technology. As long as these improvements and extensions do not deviate from the basic principles and core concept of this utility model, they should be regarded as equivalents of this utility model and are equally protected by patent rights.

Claims

1. A circuit for detecting a loose connection in a grounding wire, characterized in that, This includes the first resistor R2, the second resistor R3, the third resistor R4, the load under test RL, the integrated operational amplifier U4, the transistor Q2, and the power supply VCC; The output of the integrated operational amplifier U4 is connected to the base of the transistor Q2. The emitter of the transistor Q2 is divided into two paths: the first path is connected to the inverting input of the integrated operational amplifier U4, and the second path is connected to the third resistor R4. The third resistor R4 is divided into two paths: the first path is connected to the second resistor R3, and the second path is grounded. The second resistor R3 is divided into two paths: the first path is connected to the non-inverting input of the integrated operational amplifier U4, and the second path is divided into two paths via the first resistor R2: the first path is connected to the collector of the transistor Q2 via the load under test RL, and the second path is connected to the power supply VCC.

2. The circuit for detecting a loose grounding connection according to claim 1, characterized in that, Transistor Q2 is an NPN transistor.

3. The circuit for detecting a loose grounding connection according to claim 1, characterized in that, The power supply VCC is a DC power supply, and the voltage of the DC power supply is +5V.

4. The circuit for detecting a false ground connection of claim 1, wherein, The resistance of the second resistor R3 is equal to the resistance of the third resistor R4, and the resistance of the first resistor R2 is greater than the resistance of the second resistor R3.

5. An apparatus for detecting a ground line open, comprising: Includes the circuit for detecting loose grounding wires as described in any one of claims 1 to 4, an analog-to-digital converter module, a microcontroller module, an audible and visual alarm module, and a voltage regulator module; the voltage regulator module is used to output a +5V power supply VCC; The load under test RL is divided into two paths. The first path is connected to the collector of transistor Q2. The second path is connected to the first port of the microcontroller module via the analog-to-digital converter module. The second port of the microcontroller module is connected to the sound and light alarm module.

6. The apparatus for detecting a false ground connection of claim 5, wherein, It also includes a power-down protection module, which is connected to the third port of the microcontroller module.

7. The apparatus for detecting a false ground connection of claim 5, wherein, The audible and visual alarm module includes a first module and a second module; The first module includes a fourth resistor R5, a transistor Q1, and a buzzer LS1. One end of the fourth resistor R5 is connected to the base of the transistor Q1, the collector of the transistor Q1 is connected to the power supply VCC, and the emitter of the transistor Q1 is grounded through the buzzer LS1. The other end of the fourth resistor R5 is connected to the microcontroller module. The second module includes a first light-emitting diode D1, a second light-emitting diode D2, a fifth resistor R6, and a sixth resistor R7. The microcontroller module is connected to the cathodes of the first light-emitting diode D1 and the second light-emitting diode D2, respectively. The anode of the first light-emitting diode D1 is connected to the power supply VCC via the fifth resistor R6, and the anode of the second light-emitting diode D2 is connected to the power supply VCC via the sixth resistor R7.

8. The apparatus for detecting a false ground connection of claim 7, wherein, Transistor Q1 is a PNP type transistor.

9. The apparatus for detecting a false ground connection of claim 7, wherein, The resistance values ​​of the fourth resistor R5, the fifth resistor R6, and the sixth resistor R7 are equal.

10. A device for detecting a loose connection in a grounding wire according to claim 6, characterized in that, The microcontroller module uses the STC89C52 chip; the analog-to-digital converter module uses the ADC0832 chip; the power-down protection module uses the 24C02 chip; the regulated power supply module uses the LM7805CT chip; and the integrated operational amplifier U4 uses the LM358 operational amplifier.

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