Siemens siprotec 7SD5 User Manual page 76

2 Functions
By the way, the two above possibilities for two devices can be regarded as special
cases of chain and ring. The connection as shown in Figure 2-7 forms a communica-
tion chain with only one chain element, and Figure 2-8 shows a ring which is com-
pressed into one two-way connection.
Figure 2-10
Communication The communication is enabled via pilot wire or direct optical fibre connections or via
Media communication networks. 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 having a transmission rate of 512 kBit/s is possible. Otherwise we rec-
ommend communication converters. A transmission via modem and communication
networks can also be realized. Please note, however, that the tripping times of the dif-
ferential protection devices depend on the transmission quality and that they are pro-
longed 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 distance depends on the type of the optical fibre. Table 2-3 lists
the options available. The modules in the device are replaceable. For ordering infor-
mation see Appendix, under Accessories.
If a communication converter is used, the device and the communication converter are
linked with a FO5 module via optical fibres. The converter itself is available in different
versions allowing to connect it to communication networks operating with two-wire
copper lines or ISDN. The order numbers can be found in the Appendix under Acces-
sories.
76
Differential protection for four ends with ring topology
7SD5 Manual
C53000-G1176-C169-1