Study Of Online Measurement System Based On PC For Cable Eccentricity

The cable eccentricity not only causes huge waste of the material but also affects the performance parameters of the cable. So it is necessary to judge whether the cable eccentricity takes place. On-line measurement system based on PC is studied in this paper.The present situation of domestic and overseas measurement system for cable eccentricity is introduced in the first part of paper. Then the principles and characteristics of the usual measure methods for measuring cable eccentricity are analyzed. Based on that, a project of on-line measurement system based on PC for cable eccentricity is brought forward. In this system, the eddy current measure method is adopted.The whole measurement system is composed of three parts: eddy current sensor, data collection system and PC. The eddy current sensor used in this system is designed according to the measuring distance principle of the eddy current and it is composed of inductive probe and exciting circuit. To make sure that it is feasible to adopt this sensor, the performances of this sensor such as frequency characteristic, stability and transverse excursive characteristic are analyzed by a lot of experiments.The output signal of the sensor is the sinusoidal signal with intermediate frequency. To sample and process this signal, a data collection circuit that centers on P89C51RD2 single chip is designed. As the output signal of the sensor passes through the data collection system, it is amplified and its amplitude is discriminated and filtered. Then the signal is transformed into 12 bits digital signal by A/Dconverter and transported to PC by serial communication circuit. In addition, the identify circuit in the data collection system can identify the position of the sample dots around the cable.The software used on PC is compiled by Visual Basic language. The PC accepts the data transported by the data collection system, analyzes the data with specify algorithm and judge whether the cable eccentricity takes place. In the end, the measure result is displayed on the software interface.