Protection for parallel lines in an electrical energy supply network

The method involves connecting a protection device (13a) to a line (11a) of an electrical power supply system for detecting measured values indicating operating state of the line. Another protection device (13b) is connected to another line (11b), where the two devices exchange the detected measured values and/or signals derived from the measured values with one another. The measured values detected at the lines and the measured values and/or signals received by the protection devices are utilized for implementing a main protection algorithm of the protection devices. An independent claim is also included for a protection system comprising a control device.