Planar Sensors for Online Detection and Region Identification of Turn-to-Turn Faults in Transformers

Among the various techniques for transformer protection, more accurate, sensitive, and secure results can be achieved by the flux-based ones. The symmetrical form of the magnetic flux distribution will be disturbed due to any fault occurrence in the transformer windings. So, it seems that this is an appropriate criterion to achieve a suitable protection algorithm, while it can be used to detect faults as well as identify the faulty phase/region. In this paper, a miniature sensor is proposed consisting of simple planar magnetic flux sub-sensors and located in the existing space between the transformer core and the first insulating layer to sense the leakage flux distribution. Comparing the induced voltages in symmetrical sub-sensors for each phase exhibits asymmetrical configuration of the leakage flux distribution and identifies the faulty region in that phase. Appropriate fine and tiny construction of the proposed sensors provides them a good choice to install in the transformer core vicinity. Then, the leakage flux can be sensed in the origin regions during turn-to-turn faults. Experimental results show that such sensors have high sensitivity to detect leakage flux that ejects from the core or comes back to it.