Experimental Assessment of Dielectric Stability in Transformer Oil Using Partial Discharge Energy Signatures

The assessment of dielectric stability in transformer oil is a critical aspect of condition monitoring in high-voltage equipment. Partial discharges (PDs) are widely recognized as early indicators of insulation degradation, including the progressive degradation of insulating oil; however, their behavior under stable dielectric conditions remains insufficiently characterized in controlled experimental environments.

This work presents an experimental approach to evaluate dielectric stability through the analysis of partial discharge energy signatures derived from electrical measurements. A modular test cell was developed to reproduce controlled PD conditions using spherical electrodes with adjustable inter-electrode distances. This configuration allows the generation of repeatable discharge events under well-controlled electrical conditions representative of early-stage insulation stress. Repeated experiments were conducted under controlled experimental configurations, and current signals were recorded during each discharge event using synchronized measurement equipment. The analysis focuses on physically interpretable indicators, including peak current amplitude and energy-based descriptors computed from the electrical signals.

The results show that, under stable dielectric conditions, these indicators exhibit low dispersion and no significant drift across repeated measurements, indicating stable dielectric behavior and consistent discharge mechanisms.

These findings demonstrate that PD energy signatures can serve as reliable and practical indicators for monitoring dielectric stability and detecting early signs of insulation degradation in transformer oil. The proposed approach provides a relevant basis for condition monitoring strategies in high-voltage insulation systems and is particularly suited for early-stage diagnostics.