Method and device for monitoring polyphase lines and for detecting phase losses based on the phase angle between phase-to-phase voltages

摘要

The method according to the invention, for monitoring and protecting alternating current threephase lines, comprises the following operations: a) finding the course of the three concatenate voltages (Vab, Vac, Vbc) between a phase and another phase; b) determining the three phase-differences (”Õab-ac, ”Õac-bc, ”Õab-bc) between the three pairs (Vab-Vac; Vab-Vbc; Vac-Vbc) of concatenate voltages; c) checking whether at least one of the three phase-differences (”Õab-ac, ”Õac-bc, ”Õab-bc) between the several pairs of concatenate voltages is comprised in its respective admissible phase-difference range. This allows providing protection and monitoring relais able to operate in a very wide range of line voltage rating. The invention also relates to a device arranged for carrying out such method.