Method for obtaining a backup function for a digital distance relay and relay to carry out the method

摘要

The invention relates to a method and a relay for carrying out this method for obtaining a backup function for a digital distance relay in the case of faults in the signal processing of said distance relay comprising a central control unit (5), a databus (4), measurement signal units (1, 2, 3) for generating measurement signals from the different measuring zones (Z1, Z2, Z3) of the distance relay in a power supply system. The method comprises testing the distance relay continuously, in case of a faultless network, with respect to the digital signal processing by means of a central control unit (5). In case of a characteristic fault on the network, the distance relay is switched over from testing to protective function involving measurement by means of measurement signal units (1, 2, 3) included in the distance relay. In case of a fault on the network coinciding with a fault in the digital signal processing, faults signals (F1, F2, F3) from the measurement signal units via time lag circuits (6,7,8) and logical elements (9, 10) bring about tripping of the line section inflicted by the fault. When a fault is detected in the digital signal processing, an alarm function (ALARM) is triggered.