Assessment of Dielectric Properties and Breakdown Strength of Oil-Impregnated Reclaimed Cellulose Paper

Abstract

Cellulose paper remains the dominant solid insulation in oil-immersed power transformers due to its costeffectiveness and excellent dielectric and mechanical behavior. However, during the manufacturing of insulation assemblies, a significant amount of cellulose paper is discarded as waste due to its small, unused size, despite being unused factory remnants. Reclaiming and reusing these remnants presents an opportunity to reduce: material waste, production costs, raw material consumption, and support sustainable manufacturing. The present work provides a systematic evaluation of recycled cellulose insulation, a topic with limited prior investigation. This study provides a systematic evaluation of recycled cellulose insulation, a topic with limited prior investigation. Both recycled and standard cellulose papers were impregnated in two commonly used mineral oils, Shell DIALA S2 and Shell DIALA S4, and tested for dielectric constant, dissipation factor, and AC breakdown strength. Measurements were performed using precision LCR techniques and an IEC 60156-compliant breakdown tester. The recycled cellulose paper exhibited closely comparable results, with a difference of approximately $6 \%$ in dielectric constant and less than $1 \%$ in AC breakdown strength, confirming consistent dielectric performance and insulation reliability. These results demonstrate the recycled paper’s viability as a sustainable insulation material for high-voltage applications.