Siemens siprotec 7SD5 User Manual

2.7 Teleprotection for Distance Protection (optional)
197
7SD5 Manual
C53000-G1176-C169-1
Operation with three terminals is also possible if the device allows it. The following
figure shows the logic for two terminals.
Figure 2-82 Receive circuit of pilot wire comparison logic
The isolation voltage of the pilot wires and the binary inputs and outputs must also be
taken into account. In the event of an earth fault the induced longitudinal voltage must
neither exceed 60% of the isolation voltage of the pilot wires nor 60% of the isolation
of the device. The pilot wire comparison is therefore only suited for short lines.
2.7.11 Reverse Interlocking
If the distance protection function of the 7SD5 is used as backup protection in single-
end fed transformer feeders, the reverse interlocking function ensures a fast protec-
tion of the busbar without endangering the selectivity for faults on the outgoing feed-
ers.
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Siemens siprotec 7SD5 Specifications

General

Brand	Siemens
Model	siprotec 7SD5
Category	Relays
Language	English