This article combines the working principle of magnetostrictive level gauges and maintenance examples of magnetostrictive level gauges to share the maintenance methods and experience of magnetostrictive level gauges.
The magnetostrictive liquid level gauge consists of three parts: a measuring rod (with a built-in giant magnetostrictive line), a floating ball (with a built-in permanent magnet), and a transmitter, as shown in the figure. The current pulse generated by the transmitter circuit unit is transmitted downward along the magnetostrictive line, accompanied by a circular magnetic field. The measuring rod is equipped with a float, which moves up and down along the measuring rod as the liquid level changes. The float is equipped with a magnet, which simultaneously generates a magnetic field. When the current magnetic field and the float magnetic field meet, their magnetic fields interact to generate an instantaneous torque and form 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. The measured liquid level height can be calculated by measuring the time difference between the transmitted electrical pulse and the returned torque wave pulse.
[Maintenance example 1 of magnetostrictive level gauge] The magnetostrictive level gauge displays fluctuations during the day, but the night shift is normal.
[Fault check] The night shift voltage will be high, is the power supply abnormal? The power supply, sensor, and transmitter were inspected separately and no problems were found. Later, I saw an electric welding machine operating more than 30 meters away from the instrument. Upon careful observation, as long as the electric welding was arcing together, the liquid level display fluctuated.
[Troubleshooting] After cooperating with the welder to try to move the ground wire of the welder, the magnetostrictive liquid level gauge display returned to normal.
[Maintenance Summary] This example is a fault caused by electromagnetic interference. The welder welded in several places and was too lazy to pull the ground wire around, so he clamped the welding ground wire onto the support frame of the instrument cable bridge, causing interference to the instrument. To solve the problem of instrument interference, read the article on anti-interference measures for measurement and control instruments
[Maintenance example of magnetostrictive liquid level gauge 2] The magnetostrictive liquid level gauge displayed fluctuations and then ran to the maximum, but ultimately it simply did not display.
[Fault Check] Check that the power supply is normal. A separate power supply was used to supply power to the transmitter indicating an abnormality, but the output signal is still abnormal. When there is no display, it is found that the module of the transmitter has been damaged through re inspection.
[Fault handling] Replace the module for emergency. Contact the magnetostrictive level gauge supplier to help solve the problem.
[Maintenance Summary] This failure belongs to a quality issue with the magnetostrictive level gauge because there have been multiple identical failures of this batch of instruments on site, and the final result is that the transmitter module is burned out. This type of failure did not occur again after replacing the product.
[Maintenance Example 3 of Magnetostrictive Level Gauge] The AT100 Magnetostrictive Level Gauge gave an overrange alarm and the current reached 21mA.
[Fault check] Both the power supply and the transmitter are normal. The inspection found that the float position was too much lower than the normal zero point when the tank was empty.
[Troubleshooting] Install a stainless steel sleeve at the bottom of the float, reset the range, and then return to normal.
[Maintenance Summary] The fault in this example 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 annular magnetic field of the float is not sensitive to the lower end of the magnetostrictive line in the measuring rod, resulting in a false alarm.
Post time: 29-03-23