Development of Relay Prototype for Turn-to-Turn Fault Detection in Transformer

Digital microprocessor based protective relays that makes use of negative sequence current magnitude as well as phase difference between the primary and secondary side of the transformer are used for protection purpose. By making use of the information obtained from this data it becomes possible to detect turn-to-turn fault in transformers. However, this method involves the use of current based data for fault detection which becomes insensitive when no current flows through any one of the windings of the transformer. Such situation occurs during transformer energization during which current flows only in primary winding and no current-flow is observed in the secondary winding. Thus, the current based algorithm has some limitations and hence this paper presents development of voltage based algorithm so as to cope up with conditions of no-current flow. In voltage based algorithm, magnitude and phase angle information of voltages on both the sides of the transformer is used to detect the turn-to-turn fault during the condition of no-current flow and it is used in conjunction with the negative sequence current based algorithm which improves the reliability of the relay operating system.