PROTECTIVE RELAY DEVICE

Data from a digitizing unit is stored in a time-series data buffer, via a data receiving circuit. The data on which a digital filtering process is performed by a digital filtering processing circuit is stored in time series in a time-series instantaneous-value data storing circuit. A digital computing unit sets a time of temporally oldest data from among a group of latest time data stored in a latest time-data storing circuit as a reference time, extracts time data having the same time as the reference time from the time-series instantaneous-value data storing circuit, and then performs a digital computation.