Intelligent electromagnetic flowmeter sensor grounding considerations

Intelligent electromagnetic flowmeter installation pipelines, in general, are metal pipes, are themselves grounded, this requirement is easy to meet. However, in the case of large external electromagnetic field interference, the electromagnetic flowmeter should be provided with a grounding device. The grounding wire should be a multi-strand copper wire with a total cross-section greater than 4mm2. The ground wire of the sensor must not be connected to the common bottom wire of the motor or other equipment. Avoid the effects of leakage currents. The grounding resistance should be less than 10Î©. From the principle of the electromagnetic flowmeter and the circuit of the flow sensing signal current, the ground of the sensor and the converter must be at the same potential as the measured medium. Here are a few examples of how sensors are installed in different pipes for reference:

First, the sensor is installed on the metal pipe (no insulation coating on the inner wall of the metal pipe), as shown below

2. The sensor shall be installed on the plastic pipe or on the pipe with insulation lining. The grounding ring or the grounding flange or the short pipe with the grounding electrode shall be installed at both ends of the sensor . The measured medium flowing in the tube is short-circuited to ground and has zero potential. Otherwise, the electromagnetic flowmeter cannot work normally.

Third, when the sensor is installed on the cathodic protection pipeline, the grounding ring (or grounding flange) must be carefully installed at both ends of the sensor. Because there is a certain potential difference between the cathodically protected pipe and ground, the measured medium has a high common mode ground potential. Therefore, the sensor must use a grounding ring, otherwise the electromagnetic flowmeter cannot work normally . See below

Note: The grounding ring should be installed on both sides of the sensor. They must be insulated from the flange of the connecting pipe and connected to the sensor grounding ring through the grounding wire (2). The material of the grounding ring should be resistant to the corrosion of the medium. The standard material provided by the instrument is the stainless steel IcrI8Ni9Ti. company network.

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