A Study of a Novel Pressure Relief Valve for High-energy Internal Arcing Faults Protection on Ultra-high Voltage Power Transformers

An internal arcing fault in an ultra-high voltage power transformer can release several tens of megajoules of energy within tens of milliseconds, generating severe pressure shocks that pose a significant threat to transformer safety. Effective and efficient pressure relief is essential to enhance the transformer's arc containment capability. However, conventional pressure relief valves available on the market often fall short of protection requirements due to limitations in venting capacity and structural strength. To address this issue, this study proposes a novel pressure relief valve design featuring a significantly larger venting area and an innovative valve disk opening mechanism. First, the working principle and key characteristics of the new valve are described in detail. Subsequently, both structural and fluid dynamics analyses are performed to validate the design. A prototype valve is manufactured and evaluated through equivalent arcing tests and simulations using a small-scale transformer tank. The rolling opening mechanism improves opening efficiency and reduces the weight of individual disks. Moreover, the new valve exhibits a fourfold increase in oil flow rate compared to a valve with 172 mm flange diameter. During arcing tests, the valve operates effectively and reseals successfully, allowing for potential reuse. The tank's maximum and total deformation confirm that a single developed valve provides superior venting performance compared to two smaller valves under identical arcing conditions. This study offers a valuable protective solution for high-energy internal arcing faults in power transformers.