Functions
2.19 Undervoltage and Overvoltage Protection (optional)
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
371
Figure 2-178
Logic diagram of the undervoltage protection for positive sequence voltage system
During single-pole dead time for automatic reclosure, the stages of positive sequence undervoltage protection
are automatically blocked. In this way, the stages do not respond to the reduced positive sequence voltage
caused by the disconnected phase in case the voltage transformers are located on the outgoing side.