Study on Pressure Spread Characteristics of Arc Fault in the Oil Compartment of OLTC

As one of the core components of the converter transformer, the on-load tap changer (OLTC) is a high-incidence area of explosion accidents caused by arcing discharge faults. In order to study the process of pressure wave propagation and mechanical failure in the oil compartment of OLTC, which has a narrow and confined space, pressure simulation calculation and arcing experimental research were carried out. Based on the Structured Arbitrary Lagrangian-Euler (SALE) method, the material and mesh of the oil compartment model were processed, and the spread characteristics of the pressure wave were analyzed by the fluid-solid coupling simulation. Subsequently, the weak area in the oil compartment where there is a risk of mechanical failure under fault pressure were analyzed. The results show that after the fault occurs, the pressure wave propagates around in the form of spherical wave. The side wall and bottom position near the fault point reaches the pressure peak in about 3 ms. Since the top relief valve is far from the fault point, the time to reach the peak pressure is 5.0 ms and the peak pressure value is 13.74 MPa. Eventually, the pressure relief device opens and completes the pressure relief and the bottom of the oil compartment ruptures due to the reflection and convergence. By comparing the simulation and arc fault test results, it is confirmed that the explicit dynamics method is applicable to the analysis of pressure distribution characteristics.