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7.4.3 Remote DIFL/DIFGL trip using communication scheme
Remote differential protection (RDIF†) is designed to operate the DIFL/DIFLG relay operation
remotely when a failure occurs on communication channels. If a relay is able to make the DIFL
or DIFGL computation during the communication failure, it is preferable that other relays can
have the computation result during the communication failure; this allows issuing trip
commands on the enter lines by the DIFL/DIFGL relay during the communication failure. Note
the user is required to program transmitter and receiver logics with the PLC editor at
respective terminals with communication application (COMM_APPL‡).
†Note: For more information about the remote trip protection, see
Chapter Relay
application: DIFL applied to three-terminal line
.
‡Note: For the operation, use Wide frame structure (N=3) by setting [CH*_COM_WIDTH]
= Wide; see
Chapter Relay application: Communication application
.
§Note: Set On for the [INTCOM] in order that the scheme does not to operate incorrectly.
(i) Transmitter and receiver schemes
Figure 2.7-1 shows that the local relay sends ‘DIFL’ operation signal for opposite remote
Terminal G. Relay1 at the terminal G receives the ‘DIFL’ operation signal; Relay1 can use the
receiving signals to issue trip commands if the Relay1 cannot make DIFL computation itself.
Both Relays at Terminals G and H can receive the ‘DIFL’ operation signals. Figure 2.7-1
illustrates that the DIFL signals are transferred for the remote relays in IEEE C37.94
communication format. Table 7.4-6 shows the format and connections at Terminal J.
Figure 7.4-12 Remote trip scheme in the three-terminal configuration
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