Siemens SIPROTEC 7SD610 Manual page 51

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
Figure 2-5 Examples for communication connections
Establishing the protection data communication
When the devices of a differential protection system are linked to each other and switched on, they communi-
cate by themselves. The successful connection is indicated, e.g. with „Rel2 Login", when device 1 has de-
tected device 2. Each device of a differential protection system informs the other device of the successful pro-
tection data communication.
These are helpful features during commissioning and are described, together with further commissioning tools,
in the Section „Mounting and Commissioning". But even during operation, the proper communication of the
devices can be checked.
SIPROTEC, 7SD610, Manual
C53000-G1176-C145-6, Release date 02.2011
2.2 Protection Data Interfaces and Protection Data Topology
Functions
51