Study Of Eddy Current Measurement Technology For Cable Eccentricity

The cable eccentricity has disastrous effects on the quality of cable. So it is necessary to judge whether the cable eccentricity takes place during the process of producing cable. In view of the current situation that measurement technology for cable eccentricity is out-of-date in our country, a new eddy current measurement method is provided in this paper. According to this method, a on-line real-time automatic measurement system is designed. In addition, the measurement technology is studied from several aspects in detail. The whole eddy current measurement system for cable eccentricity is designed from three parts that are eccentricity sensor, data collector and superior system in the first part of this paper. The probe of the eccentricity sensor is designed. The problems such as power supply needed by oscillating circuit and signal transmission from rotary part to stationary part are solved. With core components of TLC2543 A/D converter and AT89C52 single chip, the data collector is designed to finish the conversion from analog signal to digital signal. The sampled data is transported to PC by RS-232 serial communication. With Visual Basic language, the software system is developed to process the data and display the result. To improve the precision of the measurement system, a analog filter and a digital filter are applied. According to the characteristic of the signal in measurement system, the performance index of the analog filter and digital filter are determined. The 3 order Butterworth analog filter and 5 order elliptic IIR digital low pass filter are designed and realized with proper methods separately. The performance of the filters are proved well through static experimental system. Eccentricity sensor is the key component of the measurement system and its performance is very important. The performance of the eccentricity sensor is studied through the static experimental measurement system. The effects of diameter of the measured cable core, turns of the measurement coil and size of the measurement probe on the performance of the eccentricity sensor are analyzed.