# The Effects of K-BNNS Nanoparticles on PD Characteristics of Composite Aramid Paper

## TL;DR

This paper studies how adding K-BNNS nanoparticles to aramid paper improves its insulation performance in high-frequency transformers by reducing partial discharge.

## Contribution

The study identifies the optimal 10% K-BNNS concentration for enhancing aramid paper's insulation properties.

## Key findings

- Aramid paper with 10% K-BNNS shows a 65.35% reduction in PD amplitude in the needle-plate model.
- Breakdown voltage increases by 32.2% and 38.5% in needle-plate and column-plate models, respectively.
- Residual charges and hydrogen bonds are key factors influencing PD characteristics.

## Abstract

Aramid paper serves as an insulating material in high-frequency power electronic transformers, and the incorporation of composite K-BNNS particles has been shown to enhance the insulating properties of aramid paper. Partial discharge (PD) is a predominant phenomenon that can lead to insulation failure in high-frequency transformers. Therefore, this paper primarily investigates the PD performances of different nanoparticle doping concentrations on aramid paper. Firstly, composite aramid papers containing K-BNNSs at different concentrations are prepared, namely 5%, 8%, 10% and 13%, respectively. Then, the experimental platforms of PD for composite aramid paper are established, and the PD performances, surface potentials, and hydrogen bonds under different high-frequency applied voltages are discussed. The experiment results show that the composite aramid paper with 10% K-BNNSs nanoparticle content has the optimal insulation performance. In the needle-plate and column-plate models, the PD amplitude decreases by 65.35% and 27.33%, respectively, when compared with non-doped aramid paper. Moreover, the breakdown voltage improves by 32.2% and 38.5%, respectively. After that, the influence mechanisms of residual charges and hydrogen bonds on the PD characteristics of composite aramid paper are analyzed. The results obtained in this paper can provide important reference for the design and selection of insulation materials for high-frequency transformers.