This article combines the working principle of magnetostrictive level gauges and on-site fault maintenance examples to share the maintenance methods and experience of magnetic flap level gauges.

The magnetostrictive liquid level gauge consists of three parts: a measuring rod (with built-in magnetostrictive wire), a floating ball (yong magnet), and a transmitter, as shown in the figure. The current pulse generated by the transmitter circuit unit is transmitted downwards along the magnetostrictive line, accompanied by the generation of a circular magnetic field. The measuring rod is equipped with a float, which moves up and down along the measuring rod with the change of liquid level. The float is equipped with a magnet, which simultaneously generates a magnetic field. When the current magnetic field meets the float magnetic field, the two magnetic fields interact, generating instantaneous torque and forming a mechanical torque wave pulse on the magnetostrictive line. The mechanical torque wave is transmitted back to the electronic component at a certain speed, and the electronic component picks up the pulse. By measuring the time difference between the emitted electrical pulse and the returned torque wave pulse, the height of the measured liquid level can be calculated.



[Repair Example 1 of Magnetostrictive Liquid Level Gauge]The magnetostrictive level gauge shows fluctuations during the day, but it is normal during night shifts.
[fault inspection]The night shift voltage will be higher, is the power supply abnormal? Checked the power supply, sensors, and transmitters separately and found no issues. Later, I saw an electric welding machine operating more than thirty meters away from the instrument. Upon careful observation, whenever an arc light is generated during welding, the liquid level display fluctuates.
[Fault handling]After cooperating with the welder to try to move the ground wire of the welding machine, the magnetostrictive level gauge display returned to normal.
[Maintenance Summary]This example is a fault caused by electromagnetic interference. The welder was welding in several places and was too lazy to pull the grounding wire, so he clamped the welding grounding wire on the support frame of the instrument cable tray, causing interference to the instrument. Solving the problem of instrument interference can be readAnti interference measures for measurement and control instrumentsarticle

[Repair Example 2 of Magnetostrictive Liquid Level Gauge]The magnetostrictive liquid level gauge showed fluctuations and then increased, but then it simply did not display anymore.
[fault inspection]Check that the power supply is normal. The transmitter with abnormal display has been powered by a separate power supply, but the output signal is still abnormal. When there was no display, upon further inspection, it was found that the module of the transmitter was damaged.
[Fault handling]Emergency module replacement. Contact the magnetostrictive level gauge supplier to come to the factory for assistance in resolving the issue.
[Maintenance Summary]This fault belongs to the quality issue of magnetostrictive level gauge, because there have been multiple similar faults of this batch of instruments on site, and the subsequent results are all transmitter module burnout. After replacing the product, this type of malfunction did not occur again.

[Repair Example 3 of Magnetostrictive Liquid Level Gauge]The AT100 magnetostrictive level gauge has an over range alarm and a current of 21mA.
[fault inspection]The power supply and transmitter are both normal. During inspection, it was found that the float position was too much lower than the normal zero point when the tank was empty.
[Fault handling]Add a stainless steel sleeve to the bottom of the float and reset the range to normal.
[Maintenance Summary]The fault in this case is that the difference between the float and the normal zero point is too large when there is no liquid level. When the float is at the bottom of the measuring rod, the circular magnetic field of the float is insensitive to the induction at the lower end of the magnetostrictive wire inside the measuring rod, resulting in false alarm phenomenon.