A method of determining out of step condition and an instance of separation within electrical power system. The method does not require user settings and ensures reliable discrimination between recoverable power swing and pole slips that indicates non-recoverable power swing and the need for system separation. The method also allows tripping at a user selected system angle if desired. A calculated angle is used to determine the magnitude of the swing current to control the tripping at the desired angle θ when the system could be safely split after detection of out of step condition based on the criteria of this invention.