IMPULSGIVARKRETS MED OLIKFORMIG KARAKTERISTIK FOR EN FLERFASIG NETSKYDDSANORDNING

摘要

In each phase, the excitation circuit has three overcurrent stages having different threshold values. The central overcurrent stage responds when the current (IR) exceeds a predetermined threshold value (IDK), where (IR>IDK) and a defect is present ( DELTA UR<0); the occurrence of a defect is detected by determining the drop in the phase voltage ( DELTA UR). Criteria combined in such a manner allow phase-selective detection of short-circuits even in the event of unfavourable load situations in high-voltage networks.