Title :
Qualification of fiber-reinforced insulating materials based on PD analysis
Author :
Kutil, Alexander
Author_Institution :
High Voltage Lab., Fed.. Inst. of Technol., Zurich, Switzerland
fDate :
8/1/1998 12:00:00 AM
Abstract :
For fiber-reinforced insulating materials used e.g. in gas-insulated system (GIS), a test procedure has been created which stresses tube shaped specimens simultaneously dielectrically and mechanically. Mechanical stress is applied by four-point bending at electric ac fields up to 12 kV/mm. To prevent surface discharges the specimens are tested in a 600 kPa SF6 atmosphere. For diagnosis a partial discharge (PD) system with a sensitivity of 100 fC has been employed. Even for high-quality vacuum-impregnated materials internal PD was detected and a clear influence of mechanical stress was found. The study of PD patterns resulted in the proposal of a prebreakdown model, which reveals the physical failure process taking place in the fiber/matrix-interface of the specimens. The model provides suitable criteria for a clear ranking of the tested materials. Also general suggestions for the improvement of fiber-reinforced insulating materials are given. For a quantitative estimation of life expectancy accelerated multifactor aging-tests are recommended
Keywords :
SF6 insulation; composite insulating materials; fibre reinforced composites; insulation testing; internal stresses; partial discharges; 600 kPa; AC electric field; PD analysis; accelerated multifactor aging test; dielectric stress; failure; fiber-reinforced insulating material; fiber/matrix interface; four-point bending; gas insulated system; life expectancy; mechanical stress; partial discharge diagnosis; prebreakdown model; vacuum-impregnated material; Dielectric materials; Dielectrics and electrical insulation; Gas insulation; Geographic Information Systems; Materials testing; Optical fiber testing; Partial discharges; Qualifications; Stress; System testing;
Journal_Title :
Dielectrics and Electrical Insulation, IEEE Transactions on
