The Research Of Vacuum Degree Online Detection System Based On AVR Microcontroller

The vacuum breaker is the critical part of the vacuum switch, in order to extinguish the arc current, the pressure in the vacuum breaker should be less than 0.01 Pa. The vacuum pressure in the breaker is one of the most important factor using in extinguishing of arc current, the reduction of the vacuum degree will affect the ability of extinguishing in the arc, even lead to failure of opening the arc. Therefore, we need to measure and record the real-time pressure of the interrupter in the practical application.This paper studies the domestic and foreign testing methods about the vacuum degree of the vacuum interrupter at present, combined with the present achievements, this paper studies the relation between the shield potential and the vacuum degree of the vacuum interrupter, on the basis of this, this paper proposes an online testing method based on "coupling capacitance method", we can measure the shield potential changes by placing the coupling probe near the shield, according to the relationship between the potential changes on the shield and the vacuum degree, we can infer the vacuum degree of the interrupter and realize the online detection of the vacuum degree. This paper presents an online vacuum detecting system using AVR single-chip microcontroller, finishing the collecting and the processing of the output signal of the capacitor sensor. This new theory enriches the online testing methods and the practical application in the measurement of the vacuum degree.This paper designs a set of on-line detecting experiment system of vacuum degree, including two parts:one is the experiment platform that can simulate the working condition of the vacuum interrupter and control the vacuum degree of the interrupter; the other is the sensor probe and the system of signal collecting, processing and displaying based on the AVR single-chip microcontroller. We pumped the vacuum interrupter in the experiment, and we measured the output signal of the capacitor sensor under the condition of different vacuum degree using AVR single-chip microcontroller, completing the demarcating curve of vacuum degree. We put the data of the vacuum curve into the AVR microprocessor in order to store the data. When we do the on-line detection of the vacuum degree, we need to do signal conditioning of the output signal in the capacitor sensor and then put the signal into AVR microcontroller, and we can get the vacuum degree by checking table or interpolating the data stored in the AVR, accomplishing on-line detection of the vacuum degree. The experiment results show that the on-line detecting system of vacuum degree based on AVR microcontroller can reach 10-4 precision, this system can meet the requirements of the on-line detecting site of vacuum degree.