There are two aspects to the grounding requirements of an electromagnetic flowmeter:
1. From the working principle of the electromagnetic flowmeter and the loop of the flow sensing signal current, the ground of the sensor and the converter must be at the same potential as the measured medium.
2. Grounding. With zero ground potential, reduce external interference. In general, the process pipes are all metal pipes, which are all grounded, which is easy to meet. However, in the case of large external electromagnetic field interference, the electromagnetic flowmeter should be separately provided with a grounding device. The grounding wire should be a multi-strand copper wire with a cross-section larger than 5mm2. The grounding wire of the sensor must not be connected to the common ground of the motor or other equipment. To avoid the effects of leakage current. The grounding resistance should be less than 10Ω.
a. The sensor of the electromagnetic flowmeter is installed on the metal pipe (the inner wall of the metal pipe has no insulating coating).
b. The sensor of the electromagnetic flowmeter is installed on the plastic pipe or on the pipe with insulation lining. Both ends of the sensor should be equipped with a grounding ring, or a grounding flange, or a short pipe with a grounding electrode.
The measured medium flowing in the tube is short-circuited to the ground, and has a zero potential. Otherwise, the electromagnetic flowmeter cannot work normally.
Therefore, the electromagnetic flowmeter does not require non-separate grounding devices, especially small-caliber electromagnetic flow sensors, but the separate grounding device is beneficial to the reliable operation of the instrument. That is to say, there must be a correct understanding of the grounding problem of the electromagnetic flowmeter, and it is important to pay attention to it, but it cannot be overemphasized.
Plano-concave lenses diverge the light, with a negative focal length, one of which is flat and the other is concave. It is often used for beam expansion, projection and enlargement of the focal length of the optical system. Antireflection coating options include UV, VIS, NIR, and SWIR.
Plano-concave lenses with negative focal length are often used in imaging or beam collimation applications. Coated lenses are also widely used in visible light and near-infrared fields. Germanium, silicon or zinc selenide substrates are suitable for infrared applications, and fused silica is suitable for ultraviolet application.
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