2.11 Undervoltage and Overvoltage Protection (optional)
161
7SD610 Manual
C53000-G1176-C145-4
Figure 2-59 Logic diagram of the undervoltage protection for positive sequence voltage system
During single-pole dead time for automatic reclosure the stages of the undervoltage
protection are automatically blocked in the positive sequence system so that they do
not respond to the reduced voltage caused by the disconnected phase in case the
voltage transformers are located on the outgoing side.
2.11.3 Setting Notes
General The voltage protection can only operate if, when configuring the device scope (ad-
dress 137), it has been set to Enabled. Compounding is only available if (address
137) is set to Enabl. w. comp..
The overvoltage and undervoltage stages can detect phase-to-earth voltages, phase-
to-phase voltages or the symmetrical positive sequence system of the voltages; for ov-
ervoltage also the symmetrical negative sequence system, zero sequence voltage or
a different single-phase voltage can be used. Any combination is possible. Detection
procedures that are not required are switched OFF.
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