The Research And Design Of Non-contact Measurement System Of Electrostatic Potential

In the research field of electrostatic, electrostatic potential measurement is one of the most important contents. Potential measurement is the basis of other parameters. Not only the application of electrostatic in our production and life, but also the prevention of its hazard, all call for the accurate measurement of electrostatic. Reading drift, measurement errors are the main shortcomings of the existing electrostatic instruments. Therefore, it can not meet our high precision demand.The paper analyzed the main problem of existing measurement instrument as well as the developing trend of electrostatic measurement technique home and aboard. Then we proposed and designed a non-contact measurement instrument. The device composed of signal processing system, electrostatic potential sensor, ultrasonic measuring system and signal generator. Through the phase sensitive detector which make up of IC Operational Amplifier LM324 and field effect transistor 3DJ7F, the signal processing system detect the desired signal from the mixed noises. Then, add the two-grade DC amplifier to the protect terminal of potential sensor as feedback, use high-tension electrode as the sensor guard to make sure the equal potential between the measured project and probe. Select piezoelectric ceramics to acquire data, it have good axial characteristics, the frequency of it is 40Hz, avoid the reading drift. For the sake of accurate detecting distance, and improving measuring accuracy, the paper designed a ultrasonic measuring system, it's measurement range is 0.17m-4m,accuracy is 1mm, which meet the potential measuring system. The device is high-accuracy, non-contact and has no reading drift. The instrument use DDS technique to construct a Sin wave generator, which drives the sensor to work.Experiment shows that the designed electrostatic instrument's measuring range is 0-±6000V, error is 0.15%, no-drift, meet the measuring demand.