Explosion-proof grounding resistance on-line monitoring system

Abstract

The invention relates to the field of electrical safety monitoring, in particular to an explosion-proof grounding resistance online monitoring system. The device comprises an explosion-proof housing, a pulse generator, a sensor, a microprocessor and a communication module. The explosion-proof housing is provided with a closed ground wire through hole. The pulse generator, the sensor and the microprocessor are all arranged in the explosion-proof shell, and the microprocessor is in communication connection with the pulse generator and the sensor; the communication module is in communication connection with the microprocessor; the microprocessor circularly monitors and calculates a grounding resistance value and a metal connection resistance value according to time set by a user, and actively uploads the values to a background monitoring center through the communication module. According to the invention, automatic and real-time resistance on-line measurement can be realized in an explosion-proof environment, an alarm can be given when a resistance value exceeds a threshold value, and a fault can be effectively identified.

Description

Technical Field

[0001] This invention relates to the field of electrical safety monitoring, and in particular to an explosion-proof online monitoring system for grounding resistance. Background Technology

[0002] Currently, traditional grounding resistance detection devices require power-off operation and cannot achieve online monitoring; the devices are not explosion-proof and cannot be used in explosive environments such as petrochemical plants and mines; they cannot monitor resistance values ​​in real time and cannot identify cable breakage faults. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the background technology by proposing an explosion-proof online grounding resistance monitoring system. This system can achieve automated and real-time online resistance measurement in explosion-proof environments, and can issue an alarm when the resistance value exceeds a threshold, effectively identifying faults.

[0004] The technical solution of this invention is an explosion-proof online grounding resistance monitoring system, comprising an explosion-proof enclosure, a pulse generator, a sensor, a microprocessor, and a communication module; the explosion-proof enclosure has a closed ground wire perforation; the pulse generator, sensor, and microprocessor are all housed inside the explosion-proof enclosure, and the microprocessor is communicatively connected to the pulse generator and sensor; the communication module is communicatively connected to the microprocessor; the microprocessor cyclically monitors and calculates the grounding resistance value and the metal connection resistance value according to the user-set time, and actively uploads them to the background monitoring center through the communication module.

[0005] Preferably, it integrates an RS485 interface and a DC power supply terminal.

[0006] Preferably, the explosion-proof housing houses a LoRa module and a lithium-ion battery.

[0007] Preferably, the sensor includes a potential sensor and a current sensor.

[0008] Preferably, auxiliary ground electrode B and auxiliary ground electrode C are arranged to form a loop with the auxiliary ground electrode A under test. The following ternary equations are solved to obtain the accurate grounding resistance value: R1=RA+RB∥RC, R2=RB+RA∥RC, R3=RC+RA∥RB, where RA, RB and RC are the single-pole resistances of auxiliary ground electrode A, auxiliary ground electrode B and auxiliary ground electrode C, respectively.

[0009] Preferably, RA∥RB∥RC<RA.

[0010] Preferably, the metal connection resistance value is detected in real time, and a circuit breaker alarm is triggered when the metal connection resistance value is greater than 5Ω.

[0011] Preferably, it also includes a differential amplifier, a low-pass filter, and a 24-bit Σ-Δ analog-to-digital converter.

[0012] Compared with existing technologies, this invention has the following beneficial technical effects: It enables automated, real-time online resistance measurement in explosion-proof environments, and can trigger an alarm when the resistance value exceeds a threshold, effectively identifying faults. It achieves remote, unmanned monitoring, transforming the traditional on-site periodic manual maintenance mode into an advanced predictive maintenance mode, greatly improving safety and operational efficiency. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the wireless version of the present invention; Figure 2 This is a schematic diagram of the wired version of the present invention; Figure 3 This is a circuit block diagram of the present invention; Figure 4 This is a block diagram of the control circuit system. Detailed Implementation

[0014] like Figures 1-4 As shown in the figure, the explosion-proof grounding resistance online monitoring system proposed in this embodiment includes an explosion-proof enclosure, a pulse generator, a sensor, a microprocessor, a communication module, a differential amplifier, a low-pass filter, and a 24-bit Σ-Δ ADC (analog-to-digital converter).

[0015] The explosion-proof enclosure meets the protection rating of Ex db mb IIC T4 Gb / IP66 WF2 and is suitable for hazardous environments such as petrochemical plants and mines. The enclosure features a closed-type grounding hole with dimensions of 53mm × 20mm.

[0016] The pulse generator, sensors, and microprocessor are all housed within an explosion-proof enclosure. The pulse generator injects an excitation signal into the circuit. The microprocessor communicates with the pulse generator and sensors. The sensors include a potential sensor (E) and a current sensor (I). The potential sensor measures the potential E in the circuit, and the current sensor measures the current I. The microprocessor handles signal processing, resistance calculation (R=E / I), three-point method equation solving, temperature compensation, alarm judgment, and communication scheduling. The pulse generator and constant current source, controlled by the microprocessor, form the excitation signal generation circuit, injecting a stable excitation signal into the grounded or metallic circuit. The signal acquisition and conditioning circuit includes a potential sensor, a current sensor, a differential amplifier, a low-pass filter, and a 24-bit Σ-Δ ADC, enabling high-precision acquisition and conditioning of weak voltage / current signals.

[0017] The communication module is connected to the microprocessor. The microprocessor cyclically monitors and calculates grounding resistance and metal connection resistance values ​​according to user-defined time intervals. It acquires sensor signals via a high-precision ADC and has a built-in temperature compensation algorithm for real-time resistance calculation and alarm judgment. The data is actively uploaded to the backend monitoring center via the communication module. The microprocessor outputs control signals to the excitation signal generation circuit; the analog signals acquired by the sensors are converted into digital signals by the ADC after signal conditioning circuitry and processed by the microprocessor; the processing results are uploaded to the backend system via the communication interface; the alarm circuit is directly driven by the microprocessor. The alarm output circuit integrated into the monitoring system triggers an audible and visual alarm signal when abnormal resistance is detected. The backend monitoring software receives and parses the data uploaded by each monitoring device, compares it with its internally preset alarm thresholds, and issues alarm reminders through audible and visual prompts, pop-ups, etc., and records information such as alarm time, location, and type for timely handling by maintenance personnel.

[0018] The monitoring system is available in wireless and wired versions. For example... Figure 1 As shown, in the wireless version, the explosion-proof housing houses a LoRa module and a lithium-ion battery. A DC-DC boost circuit converts the voltage to the system operating voltage, enabling wireless remote monitoring and ultra-long battery life. The LoRa communication module has a maximum communication range of 3000m, and the built-in lithium-ion battery provides at least 180 days of battery life. Figure 2 As shown, the wired version integrates an RS485 interface and a 12-24V DC power supply terminal, supports the Modbus-RTU protocol, has reverse connection / overvoltage / overcurrent protection, supports long-distance communication and power supply, and supports power supply up to 800 meters away.

[0019] To measure grounding resistance using the three-point method: Arrange auxiliary ground electrodes B and C, forming a loop with the auxiliary ground electrode A being measured. Solve the following ternary equation to obtain the accurate grounding resistance value: R1 = RA + RB∥RC; R2 = RB + RA∥RC; R3 = RC + RA∥RB; In this invention, RA, RB, and RC represent the individual resistances of auxiliary ground electrode A, auxiliary ground electrode B, and auxiliary ground electrode C, respectively. RA∥RB∥RC<RA, meaning the parallel resistance of the three grounding electrodes A, B, and C is less than the resistance of any single electrode (such as RA), because the total resistance decreases after parallel connection, conforming to the basic principle of parallel resistance. By measuring and calculating the resistance of each electrode using the three-point method, the parallel connection effectively reduces the system's grounding resistance, improves the safety of the grounding system, and enhances grounding performance. This invention applies the three-point method to an online monitoring system in an explosion-proof environment, combining it with relevant hardware structures to achieve automated and real-time measurement.

[0020] When monitoring metal circuits for theft prevention, the response time is less than 1 second. This monitoring system employs a four-wire measurement method, combining constant current source excitation and a high-precision differential amplifier circuit to detect the metal connection resistance value in real time. When the metal connection resistance value is >5Ω (the normal value should be between 0Ω and 1Ω), the microprocessor determines it as an open circuit and triggers an open circuit alarm. During monitoring, two pairs of wires are used for injecting current and measuring voltage respectively, avoiding the influence of wire resistance and improving the accuracy of small resistance measurements. The microprocessor controls a pulse generator to inject a constant current into the metal circuit, and a high-precision differential amplifier is used to measure the voltage drop across the circuit. After AD conversion, the voltage is sent to the microprocessor.

[0021] When this monitoring system is applied, for the transmission tower network: overhead ground wires are used to form a loop, enabling parallel monitoring of multiple towers (when R0≈0, the monitored value≈target tower resistance R1). For storage tank anti-static grounding: real-time monitoring of the grounding resistance of the storage tank / loading / unloading point (≤10Ω), conforming to JJF2-2003 standard. For single-point grounding modification: a monitoring loop is constructed by connecting to adjacent grounding electrodes or adding auxiliary electrodes.

[0022] This embodiment enables automated, real-time online resistance measurement in explosion-proof environments, and can trigger an alarm when the resistance value exceeds a threshold, effectively identifying faults. It achieves remote, unmanned monitoring, transforming the traditional on-site, periodic manual maintenance model into an advanced predictive maintenance model, greatly improving safety and operational efficiency.

[0023] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. An explosion-proof online monitoring system for grounding resistance, characterized in that, include: The explosion-proof enclosure has a closed-type grounding wire through-hole; A pulse generator, sensor, and microprocessor are installed inside an explosion-proof enclosure; the microprocessor is communicatively connected to the pulse generator and sensor. The communication module is connected to the microprocessor for communication. The microprocessor cyclically monitors and calculates the grounding resistance and metal connection resistance values ​​according to the user-defined time intervals, and actively uploads them to the background monitoring center through the communication module.

2. The explosion-proof grounding resistance online monitoring system according to claim 1, characterized in that, It integrates an RS485 interface and a DC power supply terminal.

3. The explosion-proof grounding resistance online monitoring system according to claim 1, characterized in that, The explosion-proof enclosure houses a LoRa module and a lithium-ion battery.

4. The explosion-proof grounding resistance online monitoring system according to claim 1, characterized in that, Sensors include potential sensors and current sensors.

5. The explosion-proof grounding resistance online monitoring system according to claim 1, characterized in that, Arrange auxiliary ground electrodes B and C to form a loop with the auxiliary ground electrode A under test. Solve the following ternary equations to obtain the accurate grounding resistance value: R1=RA+RB∥RC, R2=RB+RA∥RC, R3=RC+RA∥RB, where RA, RB and RC are the single-pole resistances of auxiliary ground electrode A, auxiliary ground electrode B and auxiliary ground electrode C, respectively.

6. The explosion-proof grounding resistance online monitoring system according to claim 5, characterized in that, RA∥RB∥RC<RA.

7. The explosion-proof grounding resistance online monitoring system according to claim 1, characterized in that, The metal connection resistance value is monitored in real time, and a circuit breaker alarm is triggered when the metal connection resistance value is greater than 5Ω.

8. The explosion-proof grounding resistance online monitoring system according to claim 1, characterized in that, It also includes a differential amplifier, a low-pass filter, and a 24-bit Σ-Δ analog-to-digital converter.

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