The internal temperatures and the ability to dissipate the heat from active part influence the windings’ insulation deterioration and determine how long power transformers are able to remain in operation. Due to the great importance of this equipment for the electrical system, studies to avoid failures and early aging are needed. This article presents an evaluation of thermal performance of power transformers and the optical fiber sensor positioning to temperature monitoring. For this, an experimental and numerical methodology is performed, comparing the measurements during the temperature rise test of single-phase prototype power transformer, under oil directed and air natural (ODAN) cooling system conditions equipped with 20 optical fiber sensors along its windings, to the obtained results of computational fluid dynamics (CFD) simulations performed in ANSYS Fluent software. It was verified that the punctual temperature measured by optical sensors may not accurately represent the critical temperatures along transformers’ windings, and the windings’ arrangements impact on oil flow and temperature distribution, as the number and positioning of block washers being necessary to be considered in previous studies for a better positioning of the sensors and temperature monitoring.

Creating time-marching unsteady governing equations for a steady state in high-speed flows is not a trivial task. Residue convergence in time cannot be achieved when using most low- and high-order spatial discretization schemes. Recently, high-order, weighted, essentially non-oscillatory schemes have been specially designed for steady-state simulations. They have been shown to be capable of achieving machine precision residues when simulating the Euler equations under canonical coordinates. In the present work, we review these schemes and show that they can also achieve machine residues when simulating the Navier–Stokes equations under generalized coordinates. This is carried out by considering three supersonic flows of perfect fluids, namely the flow upstream a cylinder, the flow over a blunt wedge, and the flow over a compression ramp.

Arc flashes pose significant hazards to personnel working with energised power lines due to their high thermal risk, quantified by incident energy (IE) in joules or calories per area. Accurate estimation of IE is crucial for ensuring safety. The most widely employed method for estimating IE from an arc flash is outlined in IEEE Std 1584‐2018, which applies exclusively to three‐phase AC arc flashes. However, limited research has explored alternative methods due to the complexities, costs, and preparation involved. Numerical simulations offer a viable alternative for studying arc flashes. This paper introduces a multiphysics simulation approach for determining IE by modelling three‐phase AC arc flashes using the magnetohydrodynamics (MHD) theory. This study exclusively investigates horizontal electrodes in open‐air (HOA) configuration due to the specific characteristics of the local power system configuration, which predominantly features overhead power lines, and the available test setup in the laboratory. The IE derived from simulations is compared with measurements from an arc flash laboratory based on IEEE Std 1584‐2018 and with the IE calculated by the standard itself. The results indicate a significant alignment between this innovative approach and other methods for estimating IE for three‐phase arc flashes.