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7.4.2 Transfer trip using DTT scheme
The direct transfer protection (DTT†) is designed to send a trip signal to the remote terminal
using the communication. This DTT scheme makes tripping CBs on the enter lines without
delaying; this operates together with communication application (COMM_APPL‡). The user is
required to program transmitter and receiver logics with the PLC editor at respective
terminals.
†Note: For more information about the transfer trip protection, see
Chapter Relay
application: Direct transfer protection
.
‡Note: COM1 bits are used, but the COM3 and others are also possible to use when Wide
frame structure (N=3) is selected by setting [CH*_COM_WIDTH] = Wide; see
Chapter Relay application: Communication application
.
§Note: Keep in mind that the DTT scheme makes tripping all CBs unconditionally if a
trip signal is generated at any terminals. 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 DTT can transfer a TRIP signal when entire CBs should be tripped,
because the TRIP signal is injected externally at Terminal J. The DTT scheme can transfer the
TRIP signal to remote terminals G and H; the remote terminals can trip their CBs.
Figure 7.4-7 External TRIP signal sending for remote ends
Terminal J
The local TRIP signal, which is injected via a binary input circuit (BI), is transferred in the
IEEE C37.94 communication format to Terminals G and H (Figure 7.4-8). On the other hand,
the local DTT1 function can trip the CB by the remote commands from Terminals G and H.
Table 7.4-5 shows the connections at Terminal J.
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