Non-contact monitoring device for 4-20mA current loop

Abstract

The utility model discloses a non-contact monitoring device for a 4-20mA current loop. The non-contact monitoring device comprises a first detection channel, a second detection channel and a processing module which is in communication connection with the first detection channel and the second detection channel. Each of the first detection channel and the second detection channel comprises a signal acquisition unit and a signal conditioning module, the signal acquisition unit is used for detecting a current signal and an environment magnetic field signal in the current loop in a non-contact manner, and the signal conditioning module is used for performing level conversion and driving amplification on a detection signal; and the zero offset of the signal acquisition unit is adjusted through the processing module. Non-contact measurement is adopted, accidental risks caused by circuit breaking in a traditional method are avoided, the influence of an environment magnetic field is effectively restrained through difference operation of a signal monitoring and processing module of the double sensors on monitoring results, the monitoring accuracy is effectively improved, meanwhile, a digital-to-analog conversion feedback driving amplification circuit is adopted, and the reliability of the system is improved. Zero offset of the sensor is corrected in real time, and monitoring stability is improved.

Description

Technical Field

[0001] This utility model relates to the field of monitoring device technology, specifically to a 4-20mA current loop non-contact monitoring device. Background Technology

[0002] In industrial settings, voltage signal transmission is susceptible to noise interference and voltage drop due to transmission line resistance. Compared to voltage signals, 4-20mA current loops offer stronger noise resistance during transmission, and the voltage drop caused by transmission line resistance has no impact on the signal. Therefore, they are more suitable for long-distance transmission and signal conditioning. In a 4-20mA current loop, 4mA represents zero signal, the 4-20mA signal maintains a proportional relationship with the measured signal, 20mA represents the full-scale signal, and signals below 4mA but above 20mA are used for various fault alarms.

[0003] The operation of a 4-20mA current loop relies on several key components: First, it is powered by a 24V power supply; second, the transmitter regulates the 4-20mA signal to maintain a proportional relationship with the process variable; then, the 4-20mA signal is converted into a voltage input signal through the I / O input resistor of the indicator or controller; finally, the indicator or controller converts this voltage signal into the corresponding process variable of the 4-20mA signal.

[0004] Currently, verifying 4-20mA signals typically involves using a milliampere clamp meter or a series connection to measure the signal. However, milliampere clamp meters cannot provide real-time online measurement and are time-consuming. Using a series connection increases the number of points in the 4-20mA current circuit, potentially leading to more faults. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a 4-20mA current loop non-contact monitoring device.

[0006] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: A 4-20mA current loop non-contact monitoring device, comprising a first detection channel, a second detection channel, and a processing module that is communicatively connected to the first detection channel and the second detection channel respectively;

[0007] Both the first and second detection channels include a signal acquisition unit and a signal conditioning module that is communicatively connected to the signal acquisition unit. The signal acquisition unit is used for non-contact detection of current signals and ambient magnetic field signals in the current loop. The signal conditioning module is used for level conversion and drive amplification of the detection signals, and the processing module adjusts the zero-point offset of the signal acquisition unit.

[0008] The processing module is communicatively connected to the signal conditioning module. The processing module performs differential calculations on the output signals of the two detection channels to eliminate environmental magnetic field interference and outputs an effective signal corresponding to the actual current value in the current loop.

[0009] Furthermore, the signal conditioning module includes a level conversion module and a drive amplification module. The output signal of the signal acquisition unit is electrically connected to the input terminal of the analog-to-digital conversion module of the processing module through the level conversion module, and then the output terminal of the analog-to-digital conversion module of the processing module is processed by the drive amplification module and fed back to the signal acquisition unit.

[0010] Furthermore, it also includes a communication module, which is connected to the processing module and exchanges data with the terminal device through the communication module.

[0011] Furthermore, it also includes a power module, which supplies power to the electrical components of the device.

[0012] Furthermore, the signal acquisition unit is a Hall current sensor.

[0013] Furthermore, the processing module uses a microcontroller.

[0014] The present invention has the following beneficial effects: The 4-20mA current loop non-contact monitoring device provided by the present invention adopts non-contact measurement, avoiding the accidental risks caused by circuit breakage in traditional methods. By using the signal monitoring and processing module of dual sensors to calculate the difference of monitoring results, the influence of the environmental magnetic field is effectively suppressed, breaking through the accuracy bottleneck of single sensor and effectively improving the monitoring accuracy. At the same time, a digital-to-analog conversion feedback drive amplifier circuit is used to correct the zero-point drift of the sensor in real time, improving the stability of monitoring performance. Attached Figure Description

[0015] Figure 1 This is a block diagram illustrating the structural principle of this utility model;

[0016] Figure 2 This is a schematic diagram of the signal passing through a single sensor in this utility model;

[0017] Figure 3 This is a schematic diagram showing the signal passing through two sensors in this utility model;

[0018] Figures 1 to 3 The reference numerals in the attached figures are respectively: 1-first detection channel, 2-second detection channel, 3-processing module, 10-signal acquisition unit, 11-signal conditioning module, 110-level conversion module, 111-drive amplification module, 4-communication module, 5-power supply module. Detailed Implementation

[0019] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0020] like Figures 1 to 3 As shown, a 4-20mA current loop non-contact monitoring device includes a first detection channel 1, a second detection channel 2, and a processing module 3 that is communicatively connected to the first detection channel 1 and the second detection channel 2, respectively.

[0021] In this embodiment, both the first detection channel 1 and the second detection channel 2 include a signal acquisition unit 10 and a signal conditioning module 11 communicatively connected to the signal acquisition unit 10. The signal acquisition unit 10 is used for non-contact detection of the current signal and the ambient magnetic field signal in the current loop. The signal conditioning module 11 is used for level conversion and drive amplification of the detection signal, and the zero-point offset of the signal acquisition unit 10 is adjusted by the processing module 3. Since the current in the 4-20mA current loop is a DC current, an AC transformer cannot be used for non-contact measurement. Preferably, a Hall current sensor made according to the Hall effect principle is used. Therefore, the signal acquisition unit 10 is a Hall current sensor. The processing module 3 uses an STM32 microcontroller. The processing module 3 is communicatively connected to the signal conditioning module 11. The processing module 3 performs difference calculation on the output signals of the two detection channels to eliminate ambient magnetic field interference and outputs an effective signal corresponding to the actual current value in the current loop.

[0022] In this embodiment, the signal acquisition unit 10 in the first detection channel 1 is a first Hall current sensor, and the signal acquisition unit 10 in the second detection channel 2 is a second Hall current sensor.

[0023] The Hall effect sensors of the first detection channel 1 and the second detection channel 2 satisfy one of the following conditions:

[0024] (i) The first Hall effect sensor detects the superposition signal of the current signal and the ambient magnetic field, while the second Hall effect sensor only detects the ambient magnetic field signal.

[0025] (ii) Both the first Hall effect sensor and the second Hall effect sensor detect the superposition signal of the current signal and the ambient magnetic field, and the flow direction of the measured current in the two is opposite.

[0026] Processing module 3 eliminates environmental magnetic field interference in the following ways:

[0027] When condition (i) is met, the detection value of the first Hall effect sensor is subtracted from the detection value of the second Hall effect sensor to obtain an effective measurement signal;

[0028] When condition (ii) is met, the effective measurement signal is obtained by subtracting the detection values ​​of the first Hall effect sensor and the second Hall effect sensor and then dividing by 2.

[0029] In this embodiment, the signal conditioning module 11 includes a level conversion module 110 and a drive amplification module 111. The signal output from the signal acquisition unit 10 is electrically connected to the input terminal of the analog-to-digital conversion module of the processing module 3 through the level conversion module 110, and then processed by the drive amplification module 111 and fed back to the signal acquisition unit 10.

[0030] Specifically, the output signal of the first Hall current sensor is electrically connected to one input terminal of the microcontroller's analog-to-digital converter module via a corresponding level conversion module 110, and the output signal of the second Hall current sensor is electrically connected to the other input terminal of the microcontroller's analog-to-digital converter module via a corresponding level conversion module 110. After the microcontroller acquires the signals from the first and second Hall current sensors, it processes them to obtain the current values ​​passing through the first and second Hall current sensors. The measured values ​​of the first and second Hall current sensors are subtracted to eliminate environmental influences and obtain the valid measured values. One output terminal of the microcontroller's analog-to-digital converter module is connected to the first Hall current sensor via a drive amplification module 111 to adjust the output zero point of the first Hall current sensor. The other output terminal of the microcontroller's analog-to-digital converter module is connected to the second Hall current sensor via a drive amplification module 111 to adjust the output zero point of the second Hall current sensor.

[0031] In addition, this device also includes a communication module 4 and a power supply module 5. The communication module 4 is communicatively connected to the processing module 3 and exchanges data with the terminal equipment through the communication module 4. The power supply module 5 supplies power to the electrical components of the device.

[0032] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A 4-20 mA current loop non-contact monitoring device, characterized by, It includes a first detection channel (1), a second detection channel (2), and a processing module (3) that is communicatively connected to the first detection channel (1) and the second detection channel (2), respectively; The first detection channel (1) and the second detection channel (2) both include a signal acquisition unit (10) and a signal conditioning module (11) that is communicatively connected to the signal acquisition unit (10). The signal acquisition unit (10) is used for non-contact detection of current signals and ambient magnetic field signals in the current loop. The signal conditioning module (11) is used for level conversion and drive amplification of the detection signal, and the zero-point offset of the signal acquisition unit (10) is adjusted by the processing module (3). The processing module (3) is communicatively connected to the signal conditioning module (11). The processing module (3) performs difference calculation on the output signals of the two detection channels to eliminate environmental magnetic field interference and outputs an effective signal corresponding to the actual current value in the current loop.

2. The 4-20 mA current loop non-contact monitoring device of claim 1, wherein, The signal conditioning module (11) includes a level conversion module (110) and a drive amplification module (111). The signal output of the signal acquisition unit (10) is electrically connected to the input terminal of the analog-to-digital conversion module of the processing module (3) through the level conversion module (110), and then processed by the drive amplification module (111) and fed back to the signal acquisition unit (10).

3. The 4-20 mA current loop non-contact monitoring device of claim 1, wherein, It also includes a communication module (4), which is communicatively connected to the processing module (3) and exchanges data with the terminal device through the communication module (4).

4. The 4-20 mA current loop non-contact monitoring device of claim 1, wherein, It also includes a power module (5) to supply power to the electrical components of the device.

5. The 4-20 mA current loop non-contact monitoring device of claim 1, wherein, The signal acquisition unit (10) is a Hall current sensor.

6. The 4-20 mA current loop non-contact monitoring device of claim 1, wherein, The processing module (3) uses a microcontroller.

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