ACCIDENT ASPECT DECISION DEVICE

PROBLEM TO BE SOLVED: To contribute to prompt and secure recognition of an abnormal accident aspect and to reduce a load on a person in charge at the supervision point of an electric power system.SOLUTION: An accident aspect decision device 4 obtains voltage waveform data of each phase voltage of the three phases and a zero phase voltage, detects the presence or absence of a decrease of each phase voltage and the presence or absence of an increase of the zero phase voltage on a cycle-by-cycle basis, based on the voltage waveform data, and detects the accident aspect including a short circuit between phases and a ground fault of each phase on a cycle-by-cycle basis, based on the detection results of the presence or absence of the decrease of each phase voltage and the presence or absence of the increase of the zero phase voltage. When the detection of the accident aspect continues for a predetermined number or more of cycles or the type of the accident aspect changes, the accident aspect decision device 4 decides the accident aspect is such an abnormal aspect that manual confirmation is necessary.