Life Estimation of Thermally Stressed Insulating Papers of Rotating Machines by Using Arrhenius Model

In the present study, life estimation of accelerated aged insulating papers used in rotating machines is estimated by Arrhenius model. Various types of insulating papers used in rotating machines such as Mylar, Nomex-Mylar-Nomex(NMN), Leatheroid, Dacron-Mylar-Dacron(DMD), Mica Tape, and Kapton are thermally aged at 90°C, 130°C and 170°C with 300hrs duration of each sample. These insulating materials wrapped on copper conductor with single and double layer. Then, breakdown voltage test is performed at each temperature for both single and double layer papers to determine their dielectric strength. Further, correlation analysis between breakdown voltage and different applied temperatures is performed for all paper samples. Popular Arrhenius plot is drawn by short term test data on breakdown voltage for an extrapolation to long term performance of various types of insulating paper used in rotating machines. The results showed that the performance of double layer insulation is almost twice than single layer performance. The aging analysis and testing of insulating papers was performed in TIFAC-Core centre of NIT Hamirpur, H.P., India.