Power transformers are central elements of power transmission systems and their deterioration can lead to system failures, causing major disruptions in service. Catastrophic failures can occur, posing major environmental hazards due to fires, explosions, or oil spillage. Early fault detection can be accomplished or estimated using electrical sensors or a chemical analysis of oil or gas samples. Conventional methods are incapable of real-time measurements with a low electrical noise due to time-consuming analyses or susceptibility to electromagnetic interference. Optical fiber sensors, passive elements that are immune to electromagnetic noise, are capable of structural monitoring by being enclosed in power transformers. In this work, optical fiber sensors embedded in 3D printed structures are studied for vibration monitoring. The fiber sensor is encapsulated between two pressboard spacers, simulating the conditions inside the power transformer, and characterized for vibrations with frequencies between 10 and 800 Hz, with a constant acceleration of 10 m/s2. Thermal aging and electrical tests are also accomplished, aiming to study the oil compatibility of the 3D printed structure. The results reported in this work suggest that structural monitoring in power transformers can be achieved using optical fiber sensors, prospecting real-time monitoring.

Power transformers have an imperative role in the future developments of the electrical grids. Treated as crucial assets for transportation and distribution of electrical energy, transformers are currently being studied regarding to the integration of technologies aiming to diagnose problems and monitoring data of electrical power grid. Furthermore, environmental noise pollution has gained importance, especially in active units of the power grid, located near consumers, such as transformers. Transformers noise can be classified according to its source: core, windings and cooling. This study addresses an experimental characterization of one of the main causes of transformers core noise-magnetostriction of electrical steel. An evaluation of magnetostriction properties of electrical steel, including resistive strain gauges and Fiber Bragg Gratings (FBGs) measurements with an Epstein frame, are presented and discussed. The magnetic flux density influence on hysteretic strain behavior of magnetostriction was evaluated, as well as the effect of a clamping load on core joints. Nowadays, optical interrogators for Bragg gratings have a high acquisition frequencies and wavelength sensitivity when compared to former optical interrogation systems, allowing to evaluate physical phenomena without electromagnetic interference and with equivalent resolution of conventional strain gauges.

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In this work, a brief review on the application of fiber optic sensors on power grid apparatus is presented. Power transformers, which are the nodes between electrical transmission lines, are the most expensive, critical and one of the central units of this network. The failure of electrical machines compromises the whole grid leading to power outages and income losses. Thus, constant monitoring of structural health and operating conditions of core infrastructures is sought. With different types of sensors either on the market or in the literature, it is possible to measure physical parameters that make this equipment more reliable.