Functions
2.2 Protection Data Interfaces and Protection Data Topology
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
76
Figure 2-10 Differential protection for four ends with ring topology
Communication media
Communication can be effected via different communication connections. Which kind of media is used depends
on the distance and on the communication media available. For shorter distances, a direct connection via
optical fibres with a transmission rate of 512 kBit/s is possible. Otherwise, we recommend communication con-
verters. A transmission via modems and communication networks can also be realized. Please note, however,
that the tripping times of the differential protection devices depend on the transmission quality and that they are
prolonged in case of a reduced transmission quality and/or an increased transmission time. Figure 2-11 shows
some examples for communication connections. In case of a direct connection, the bridgeable distance
depends on the type of the optical fibre (refer to Chapter 4). Different types of communication modules can be
installed in the devices. For ordering information, refer to Appendix, under “Ordering Information and Accesso-
ries”.
If a communication converter is used, the device and the communication converter are linked with an FO5
module via optical fibres. The converter itself is available in different versions allowing to connect it to commu-
nication networks (X.21, G703 64 kBit, G703 E1/T1) or connection via two-wire copper lines. Use the FO30
module to connect the device to the communication networks via IEEE C37.94. For the ordering information,
please refer to the Appendix under “Ordering Information and Accessories”.
Note
If the protection data interfaces of the devices are connected via a communication network, a circuit switched
network, e.g. a SDH and/or PDH-network is required. Packet switched networks, e.g. IP-Networks, are not suit-
able for protection data interface communication. Networks of this type do not have deterministic channel
delays as the symmetrical and asymmetrical channel delays vary too much from one telegram to the next. As
a result it is not possible to obtain a definite tripping time.
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