Protection Communication And Supervision - ABB RELION 615 Series Applications Manual

Section 2
RED615 overview
2.7.3
26

Protection communication and supervision

The communication between the relays is enabled by means of a dedicated fiber optic
communication channel. 1310 nm multi-mode or single-mode fibers with LC connectors
are used for line differential communication. The channel is used for transferring the
phase segregated current value data between the relays. The current phasors from the two
relays, geographically located apart from each other, must be time coordinated so that the
current differential algorithm can be executed correctly. The so called echo method is used
for time synchronization. No external devices such as GPS clocks are thereby needed for
the line differential protection communication.
Apart from the continued protection communication, the communication channel can also
be used for binary signal transfer (BST) that is, transferring of user configurable binary
information between the relays. There are a total of eight BST signals available for user
definable purposes. The BST signals can originate from the relay's binary inputs or
internal logics, and be assigned to the remote relay's binary outputs or internal logics.
The protection communication supervision continuously monitors the protection
communication link. The relay immediately blocks the line differential protection
function in case that severe interference in the communication link, risking the correct
operation of the function, is detected. An alarm signal will eventually be issued if the
interference, indicating permanent failure in the protection communication, persists. The
two high-set stages of the overcurrent protection are further by default released.
RED615
GUID-8CE71CC9-F0EA-4BE9-B693-173CAEA9FA58 V2 EN
Figure 9: Fiber optic protection communication link
Fibre-optic line differential
communication link
Protection communication and supervision
Binary signal transfer
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