Work

Phased Array Ultrasonic Testing and Imaging Technology for Gas-Gap Defects in Dry-Type Bushings

Year: 2026

Type: article

Abstract: Dry-type bushings are critical insulation components in power systems, where internal gas-gap defects can trigger insulation degradation and threaten operational reliability. To address the limited localization accuracy and poor visualization of conventional electrical diagnostics, this study proposes a Phased Array Ultrasonic Testing method combined with the Total Focusing Method (TFM) for detecting gas-gap defects in dry-type bushings. A two-dimensional finite-element model of the multilayer epoxy resin-paper-aluminum foil structure was established to investigate the feasibility and mechanisms of gas-gap defect detection under different excitation frequencies. Results indicate that 5 MHz provides the optimal balance between penetration depth and spatial resolution for multilayer heterogeneous media. Experimental validation was performed on fabricated specimens containing gas-gap defects using a custom open-platform phased-array system. The proposed method successfully identified gas-gap defects with clear imaging and controllable localization error, in good agreement with simulation results. These findings demonstrate that ultrasonic phased-array imaging with TFM offers an effective non-destructive solution for high-resolution detection of gas-gap defects in dry-type bushings.

Source: IEEE Transactions on Dielectrics and Electrical Insulation

DOI: 10.1109/tdei.2026.3752418

Authors: Yu Hou, Hao Yang, Yuanshuai He, Yajun Qiao, Fusheng Zhou, Chao Gao

Institutions: Xi'an Polytechnic University, China Southern Power Grid (China)

Language: English

Topic: Ultrasonics and Acoustic Wave Propagation

Subfield: Mechanics of Materials

Field: Engineering

Domain: Physical Sciences

SDG: Industry, innovation and infrastructure

Open Access status: hybrid

Estimated APC paid: $2,645