Earth leakage protection unit for Three=phase current mains - carries out angular measurement between displaced voltage occurring at star point of 3 phase current mains and reference voltage and has fault signal producer

摘要

The fault signal producer produces a fault signal, depending on the angle measured, for the respective phase with earth leakage of the three phase mains (5). The reference voltage is an interlinked voltage between the phases of the three phase mains. The displacement voltage and the interlinked voltage are determined outside the earth leakage protection unit (3) and the unit (13) for the angular measurement are lead over corresponding terminals (11a,11b) of the earth leakage protection unit (3). ADVANTAGE - Less complicated and costly than unit hitherto used for selective signalling of faulty phase.