TY  - JOUR
AU  - WANG, Yiming
AU  - LUO, Ning
AU  - WEI, Yucheng
AU  - ZHANG, Hu
AU  - WANG, Lujia
PY  - 2026
TI  - Dynamic response and failure mechanism of current transformer pressure relief devices under explosive load
JO  - Explosion and Shock Waves
SN  - 1001-1455
VL  - 46
IS  - 11
AB  - Current transformers are core components of power systems used for current measurement and relay protection. During long-term service under coupled multiphysical-field conditions, the internal insulation structure is susceptible to breakdown under locally intensified electric fields, triggering arc discharge in the insulating oil. The resulting oil cracking and rapid gas expansion produce a sharp rise in internal pressure. If this pressure is not relieved promptly, the resulting pressure surge may lead to combustion and explosion accidents. Therefore, the rapid-response capability of pressure relief devices under explosive loading is critical to the operational safety of current transformers. This study focuses on the expander–rupture disc pressure relief assembly of an LVB-220 current transformer and systematically investigates its dynamic mechanical behavior and failure mechanism under explosive impact loading. An equivalent hydrogen-air premixed-gas explosion test platform was constructed. The test system consisted of two stainless-steel flame-acceleration tubes with an inner diameter of 168.3 mm and a total length of 4250 mm, a gas-filling and mixing unit, an ignition device, and a high-speed data-acquisition system. A hydrogen-air mixture with a volume ratio of 27∶75 was used as the combustible gas to reproduce the most severe explosion conditions caused by arc-generated cracking gas in transformer oil. Pressure and flame signals were recorded synchronously using a high-temperature pressure transducer and two flame detectors installed along the tube. The tested assembly consisted of a positive-arch, cross-scored rupture disc made of 316L stainless steel, with a static burst pressure of 0.2 MPa, and a nine-convolution expander. In addition, an explicit dynamic finite element model was developed using ANSYS/LS-DYNA. The Johnson-Cook constitutive model was adopted to describe the strain-rate-dependent behavior of 316L stainless steel. The cross-scored region of the rupture disc was finely meshed with a minimum element size of approximately 0.02 mm to accurately capture crack initiation and propagation. The measured pressure-time history was applied as the loading boundary condition. The model was validated by comparing the simulated opening pressure and expander deformation with the experimental results. The results show that, during the early stage of the explosion, the pressure wave reaches the relief port ahead of the flame front and triggers the opening of the rupture disc. The measured peak pressure before disc opening is 0.72 MPa, which is significantly higher than the static calibration value of 0.2 MPa because of strain-rate hardening, structural inertia, and the spatial nonuniformity of the pressure field under rapid loading. The expander exhibits limited plastic deformation, with the axial deformation of the nine convolutions ranging from 0.60 to 2.30 mm. The deformation distribution is characterized by larger values at both ends and smaller values in the middle, reflecting an energy-absorption mechanism dominated by low-order bending modes. The asymmetric curling of the rupture-disc petals is closely associated with stress-wave reflections and fluid-structure interaction induced by high-speed venting. The numerical simulation reproduces the crack-growth sequence, opening morphology, and stress distribution in good agreement with the experimental observations. The proposed integrated experimental-numerical approach provides a reliable mechanical basis and engineering guidance for optimizing the blast-resistant design of pressure relief devices for current transformers.
UR  - https://doi.org/10.11883/bzycj-2026-0022
DO  - 10.11883/bzycj-2026-0022