Fast Arc Detection in Power Transformer Using Fiber Optic Sensor

Arc is one of the most dangerous faults in transformers, and it can increase the internal pressure of the transformer tank within milliseconds, resulting in serious consequences such as explosion. Transformers are equipped with Buchholz relays (BHR) to detect faults, enabling circuit breakers (CB) to disconnect the transformer. The time duration between the internal fault occurrence and the disconnection of the transformer is typically around 100 milliseconds. Due to the intensity of the arc energy and the sudden increase in pressure inside the transformer, the power interruption cannot be performed fast enough in some cases, leading to a tank rupture. Therefore, the objective of this investigation is to develop a method for detecting arcs before the rapid increase in pressure. To achieve this objective, a novel sensor is designed using fiber optic cable to recognize the visible light emitted by the arc. In this article, the sensor and its operation are introduced first, and then it is tested in different conditions such as different oils, temperature variations, reflecting housing, and oils with different degrees of aging. According to the results, the method presented in this study shows a high potential for fast arc detection. Moreover, this sensor is well optimized for application inside the transformer.