Investigation of a DN400 Large-Diameter Pressure Relief Valve: Design, Simulation, and Arc Fault Test

(DN172). In recent years, several cases of oil tank rupture induced by arc faults have been reported in UHV transformers, revealing the deficiencies of existing pressure relief devices in terms of response sensitivity and relief capacity. The effective oil discharge diameter is the paramount factor influencing pressure relief performance; nevertheless, enlarging the effective relief diameter inevitably increases the mass of the diaphragm disc, which severely impairs its actuation speed. To resolve this contradiction, this study innovatively proposes a design approach integrating a modular assembled diaphragm disc and a rotary opening mechanism, which achieves a significant improvement in actuation speed while guaranteeing the pressure relief area. A numerical model was constructed, and flow field simulations were performed under identical inlet pressure conditions. The simulation results demonstrate that the pressure relief capacity of the DN400 PRV exceeds four times that of the DN172 counterpart. A DN400 PRV prototype was fabricated and tested under a 3.2 MJ arc fault simulation scenario. Experimental data show that the tank wall pressure reduced by 83.88% after the DN400 PRV was triggered, which is remarkably better than the 53.17% pressure drop achieved by the DN172 valve. Additionally, the oil tank remained undamaged post-test, fully validating its excellent pressure relief and explosion suppression capabilities.