Electromagnetic flowmeter electromagnetic loss in several ways

The electromagnetic loss of the electromagnetic flowmeter is caused by a variety of factors. There may be interference from the surrounding magnetic field that causes loss, or the structure of the flowmeter itself causes interference in signal transmission. No matter what the factors are, usually, the electromagnetic flowmeter There are several ways of electromagnetic loss:

Hysteresis loss: Hysteresis loss is caused by the hysteresis characteristics of magnetic materials. After the coil is supplied with alternating current, due to the hysteresis phenomenon of the magnetic material, the magnetic flux phase lags behind the current phase by a certain angle (hysteresis angle). When the magnetic induction intensity in the iron core does not reach saturation, the hysteresis loss is very small. Therefore, the yoke and iron core of the electromagnetic flowmeter are made of electrical silicon steel sheets with high magnetic permeability. The rolling direction of the silicon steel sheets is consistent with the direction of the magnetic lines of force. In this way, the hysteresis loss is greatly reduced and can be ignored.

Eddy current loss: Eddy current loss in the yoke. The yoke should be made of sheets with high magnetic permeability and low electrodynamic rate. Each sheet should be insulated to reduce losses. Usually, it is suitable for the mains power supply of tens of hertz. frequency, the thickness of the silicon steel sheet is 0.25~0.5mm, which can prevent the eddy current loss from exceeding the allowable value.

Eddy current losses in metal measuring tubes: The higher the frequency of the excitation power supply, the stronger the magnetic field intensity, the longer the axial length of the magnetic field, the larger the diameter of the measuring tube, and the thicker the wall thickness, the greater the eddy current loss. The larger the value, the greater the eddy current loss, and the greater the phase difference angle between the magnetic induction intensity and the magnetic field current.