A Comprehensive Characterization of Glass Fiber Wire: Thermal Life, Electrical Life, and Partial Discharge

This paper presents a comprehensive investigation of glass-fiber wire insulation, evaluating its thermal life, electrical life, partial discharge (PD) behavior and the impact of combined thermal and electrical ageing on insulation lifetime. Thermal endurance tests were conducted to establish thermal life versus temperature characteristics. The impact of thermal ageing was assessed by monitoring dissipation factor and insulation capacitance, confirming progressive degradation within the insulation. The time-to-failure of each sample was estimated and statistically analyzed using Weibull probability distribution to develop life models. The model, derived at the 50% failure percentile, was compared with manufacturer data, showing close agreement with a percentage error of only 0.44%. Subsequently, electrical ageing tests were conducted to determine electrical life versus voltage excitations. PD measurements under PWM excitation were then carried out to evaluate the impact of pulse frequency, rise time, and duty cycle on the PDIV of glass-fiber insulation. Finally, the impact of combined thermal and electrical ageing on the life of glass-fiber insulation is evaluated using Miner’s law. A combined representative thermo-electrical stress profile is suggested under which the insulation has consumed approximately 96.3% of its lifetime, corresponding to 7,704 hours out of the targeted 8,000 hours lifetime.