Common anti-interference methods of electromagnetic flow meter

Abstract: Information on common anti-interference methods for electromagnetic flowmeters is provided by excellent flowmeter and flowmeter manufacturers. The measurement principle of the electromagnetic flowmeter is based on Faraday's law of electromagnetic induction, and the original signal it generates is very weak, less than a millivolt. If there is strong electromagnetic field radiation near the flowmeter, such as motors, transformers, inverters and other devices that are easy to cause electromagnetic interference. More flowmeter manufacturers choose models and price quotations. You are welcome to inquire. The following are the details of the articles on common anti-interference methods for electromagnetic flowmeters. The measurement principle of the electromagnetic flowmeter is based on Faraday's law of electromagnetic induction, and the original signal it generates is very weak, less than a millivolt. If there is strong electromagnetic field radiation near the flowmeter, such as electric motors, transformers, frequency converters and other equipment that are prone to electromagnetic interference, it will affect the measurement accuracy and even make the flowmeter unable to work normally. Therefore, how to do a good job of signal interference is particularly important. The following are some practical experiences accumulated by our company over the years for your reference. 1. Elimination of differential interference and power frequency interference: There are often differential interference and power frequency interference signals in the signal, and it is often difficult to completely filter out the power frequency interference by low-pass filtering in the signal processing circuit. The company adopts synchronous sampling and power frequency compensation technology to suppress the power frequency interference caused by the power frequency interference in the flow signal potential and the power frequency power supply frequency fluctuation, and effectively remove the differential interference. Synchronous sampling technology, the sampling start time lags the excitation signal by 1/4 cycle, the pulse width is an even multiple of the power frequency period, and the differential interference is eliminated while making the average value of the power frequency interference in the flow signal potential equal to zero to eliminate the power frequency interference The frequency fluctuation compensation of the power frequency power supply is to ensure that the excitation power supply and the sampling pulse can be adjusted synchronously in the dynamic fluctuation of the frequency, which truly realizes the synchronous sampling technology and synchronous excitation technology, synchronous A/D conversion, and reduces the differential interference and power frequency. the effect of interference. 2. Elimination of zero drift: The so-called zero drift means that when the input signal of the sensor is zero, the output of the amplifier is not zero. The zero-point drift signal will be transmitted between the amplified circuits at all levels. After multi-stage amplification, it will become a larger signal at the output end. Since the useful signal output by the sensor is weak, the zero-point drift may drown the useful signal, making the circuit unable to normal work. Therefore, in order to suppress the zero drift, the differential circuit input of three operational amplifiers is used to realize the acquisition of weak signals with large internal resistance, so as to suppress the introduction of common mode signals. After the first-stage amplifier circuit, a DC blocking capacitor is used to filter out the zero-point drift of the baseline and prevent the DC signal from being too large and exceeding the input range of the A/D conversion. 3. Other measures to remove interference: for the electromagnetic flowmeter sensor“Transformer effect”The resulting quadrature interference, using“Transmitter Zero Method”to eliminate. In terms of software design, digital filtering technology and power-down protection technology are adopted, and software instruction redundancy measures can effectively improve the reliability of input microprocessor numbers. Maintenance point of electromagnetic flowmeter: After using electromagnetic flowmeter for a period of time, it will find inaccurate measurement data. In fact, this is not the quality problem of the electromagnetic flowmeter itself. But because the user did not follow the method in the manual to maintain and maintain the flowmeter. 1. Zero point inspection and adjustment: Before the intelligent electromagnetic flowmeter is put into operation, the zero point must be adjusted when the electromagnetic flow sensor is full of liquid and static after power-on. After being put into operation, it is also necessary to periodically stop the flow for zero-point inspection according to the conditions of use; especially for precipitation, easily polluted electrodes, and non-cleaning liquids containing solid phase, more inspections should be carried out in the early stage of operation to gain experience to determine the normal inspection cycle. Compared with the rectangular wave shock, the electromagnetic flowmeter of the AC excitation method is more prone to zero drift, so more attention should be paid to inspection and adjustment. 2. Regularly check the electrical properties of the sensor. First, roughly measure the resistance between electrodes. Disconnect the signal connection between the sensor and the converter, fill the sensor with liquid, measure the resistance between the two electrodes and the ground terminal with a multimeter, whether it is within the range specified by the manufacturer, and the two measured values ​​are roughly the same. Record the resistance value of the first measurement, which is useful for later determining the cause of the sensor failure (such as whether the deposited layer is conductive or insulating). Next, empty the sensor of the liquid, wipe the inner wall, and measure the resistance between the two electrodes and the ground terminal with a megohmmeter after it is completely dry. The above are some common methods of our company, I hope it will be helpful to you. If you still have any questions that have not been solved, you can call our company, and our company will have professional technicians to answer for you. The above is the whole content of this article. You are welcome to inquire about the flowmeter selection and quotation of our factory. 'Common anti-interference method of electromagnetic flow meter'
We are a performance driven culture that uses level gauge to ensure continuous improvement.
Guangdong Kaidi Energy Technology Co., Ltd. aims to hire several additional experienced marketing professionals that can add to our existing talent-pool and help continue the steady growth of our business.
While manufacturing level gauge, we always pay attention to the technology and quality of the product.