Statistical analysis of criteria signals for power transformer inrush discrimination

This paper presents results of statistical analysis of criteria signals that can be used for power transformer inrush discrimination. All criteria signals have been defined and evaluated on basis of simulative studies of numerous transformer normal and abnormal operating conditions. For all criteria signals the respective operation thresholds are also recommended. Simulation data has been obtained with use of EMTP software. The selected criteria and their final combination reveal ability of better restraining for various energisation situations. The outcomes of this research can be further used as hints for development of new stabilization algorithms for transformer protection relays.