Menetelmät kuivuneiden öljypäätteiden havaitsemiseksi voimakaapeleissa

Cable termination is one of the important components in the electrical power system. A failure of it can cause a long interruption, costly repair and loss of revenue. An existing oil filled cable termination such as rubber tube and porcelain type of cable termination require an observation and preventive maintenance in order to prevent an enormous electrical system failure in future. One of the defects of this type of oil filled cable termination is the lack of insulation oil inside it. The worst case if it becomes totally empty and at the same time there is no approach that can help to detect it. This thesis presents the work carried out to find any possibility method that can be used to detect a drying out of oil impregnated paper tape cable terminations. Furthermore, the diagnosis has to be used without destroying the terminations. Four diagnosis methods; infrared (IR) thermography, partial discharge (PD) measurements, acoustic PD measurements and X-ray imaging are reviewed and the diagnosis result are presented. In addition, a finite element method (FEM) calculation is used to compute electrostatic and thermal field in 2D-cross section of a cable termination. The FEM simulation calculation results on electrostatic and thermal field are presented. By comparison of four diagnosis method in this work, the X-ray imaging method is the best approach to observe and detect a drying out of paper tape oil impregnated cable terminations