Generally speaking, the material level feedback is not accurate and timely, it is very easy to occur the burst event, and there is a greater safety risk. So the requirements of radar level meters are very high, but radar level meters from time to time will occur abnormal material level jump or fall, or even dead, resulting in the existence of a large error in material level measurement, bringing trouble to production and sales. Today we talk about how to reduce this error.
Causes of measurement errors in radar level meters
1, there is AC interference, and the voltage is high. For example, in the radar level meter used in the production line, the power supply requirement is 24VDC (typical value), but the field measurement found that the power supply shows 27.2V, significantly higher than 24VDC, resulting in large measurement results, and even the radar level meter will appear dead phenomenon.
2, the radar level meter installation position is not correct resulting in measurement deviation, for example, the accumulation of aggregate in the transit bin is a ” mountain ” cone, but only in the return belt near the lower material mouth installed a radar level meter, the installation position is too close to the lower material mouth of the return belt, and at the same time is too far from the two sides of a broken feed belt lower material mouth. The radar level meter is directly below the drop point of the return material belt, the distance is too close, and the falling aggregate will interfere with the radar level meter and form false reflection.
3, the radar level meter emits head of the impact of dust accumulation because the radar level meter uses working conditions more dust, dust easy to adhere, and by the ambient temperature, dust wet easy to clump, the dielectric constant will become large adhesion radar level meter emitting head and horn wall, affecting the radar measurement accuracy and stability.
4, other factors that cause the level jump, are the measured material pile angle is very large, the reflective surface is not flat, the material has a wall phenomenon, sometimes the material will collapse, the output level in the process of falling will suddenly rise, resulting in level display artifacts. If the dielectric constant is relatively low, it cannot form a strong reflection to the radar wave, and the reflected wave received by the radar contains noise and false interference echoes, and the noise reduction and filtering processing work is not done in the preliminary installation and commissioning, which will also lead to the deviation of the measurement.
What are the improvement measures to reduce the measurement error of radar level meter?
1、Add an isolation device to reduce AC interference, for the supply power supply voltage is high signal interference in the transmission process, using the supply power supply and the instrument between the installation of two parallel reverse arrangement isolation modules to solve the above problem.
2, based on the analysis of the measurement conditions choose a reasonable installation location and angle, to improve the accuracy of measurement. For the radar level meter installation position, the same type of radar level meter is installed at a 1.5m position above the transit bin from the side of the two feeding belts, and the horn antenna is installed at a suitable angle when installed so that the radar wave is in a circular area with a radius of 0.5m-1m against the drop point of the lower material. At the same time, the radar level meter should not be installed in the center of the arch-shaped tank, otherwise, the interference echo will lead to signal loss. It should not be installed very close to the tank wall.
3、Keep the radar level meter probe clean and avoid the accumulation of dust and moisture scars on the probe. In view of the dust accumulation in the transmitter head, the existing radar level meter is dismantled, a plastic film is attached to the antenna horn, and the dust on the horn antenna is cleaned regularly to ensure that there is no dust accumulation in the transmitter head to ensure the measurement accuracy and stability.
4, digital filtering to reduce interference, in order to improve the accuracy of the measurement data must be noise reduction processing, the use of increased software filtering time, the use of data smoothing method, as far as possible to eliminate noise and get the actual measurement data