P4LR |1KHL015107R0001 ABB PLC Module

Important dual-circuit lines (132 kV to 400 kV) areoften equipped with duplicated line protectionand breaker failure protection on each circuit. TwoETL500 links, each with a four-command NSD550,are then arranged in a redundant teleprotectionscheme (operating mode “2+2”).Important single-circuit lines (400 kV to 800 kV) arealways equipped with duplicated main protection,breaker failure protection, and perhaps a generatorshutdown / load shedding facility. Two ETL500links, each with a four-command NSD550, are thenarranged in a fully duplicated teleprotection scheme(operating mode “2+2”).An NSD550 with its four commands can also beused for phase-segregated protection of a threephase line (operating mode “3+1”). The non-coded