The Application Research Of On-line Monitoring Technique For XLPE Cable Joint By Temperature

XLPE insulated cables are widely used in power industry etc. Its insulated faults often take place. And cable joint faults are high scale in XLPE cable faults. For this reason, the on-site detecting technique, which could reflect the insulation condition of XLPE cable joint by detecting the temperature of respective part, is presented.This paper introduces water tree aging theory of XLPE cables and insulated characteristic of water tree aged XLPE cables. Temperature of XLPE cable joint and relation with water tree are analyzed. Author establishes a math model for relation between interior temperature and exterior temperature of XLPE cable joint.The relation of interior temperature and exterior temperature of XLPE cable joint is studied in lab based on structure analyzing of XLPE cable and cable joint. It is found that theoretic result and experimental result of the difference between interior temperature and exterior temperature of VYJV22-6/10kV 3 X 300 XLPE cable joint is basically consistent.On the basis of theory and experiments, the author designs the on-site detecting system for reflecting the insulation condition of XLPE cable joint by measuring temperature. By adopting the design idea of distributed system, it is used for detecting interior temperature of XLPE cable joint. The system adopts ND type hardware module for control. This paper designs the transform and drive circuit of controlling voltage, the controlling circuit of signal boxes and signal channels, and the adjusting circuit of sensor's output-signal. At last, based on hardware, system software is designed which include the program module of ND type hardware module, controlling circuit, signal collection, data processing. Totally, this system has simple structure, high reliability, strong expansibility, easily installing and high capability-price ratio.