P.3.319
Date Code 20151029 Protection Manual SEL-411L Relay
Protection Functions
Protection Application Examples
Channel 1 has lower latency and therefore the fastest communication time. In
addition, Channel 1 communication is symmetrical, because fiber-optic
communications channels are inherently symmetrical. Therefore, choose
Channel 1 as the primary channel.
87PCH := 1 87L Primary Serial Channel (1, 2)
For security, choose unique addresses for all relays.
We would have the following at Relay S:
87TADR := 1 Relay Transmit Address (1–255)
87R1ADR := 2 Channel 1 Receive Address (1–255)
87R2ADR := 2 Channel 2 Receive Address (1–255)*
* If E87CH = 2SD, then the relay uses 87R1ADR for both channel
receive addresses. This ensures that both channels have identical
addresses.
We would have the following at Relay R:
87TADR := 2 Relay Transmit Address (1–255)
87R1ADR := 1 Channel 1 Receive Address (1–255)
87R2ADR := 1 Channel 2 Receive Address (1–255)*
*If E87CH = 2SD, then the relay uses 87R1ADR for both channel
receive addresses. This ensures that both channels have identical
addresses.
Channel 2 is configured for EIA-422 communication. Choose receive and
transmit clock edge settings to match your downstream communications
hardware.
We would have the following at both terminals:
87RXCE2 := R Channel 2 EIA-422 Receive Clock Edge (R, F)
87TXCE2 := R Channel 2 EIA-422 Transmit Clock Edge (R, F)
Channel 1 uses direct fiber, so channel asymmetry will not be an issue.
Choose channel-based data synchronization for this channel because this
method is independent from any external time sources. Channel 2
communication routes over a SONET network. On SONET networks, channel
asymmetry could be an issue. This example assumes asymmetry can be a
problem. Note that many SONET systems can ensure symmetrical channels
allowing the channel-based synchronization for the 87L elements. Time-based
data synchronization is tolerant of asymmetry, so choose T (Time-based) for
this channel.
87CH1SN := C Data Sync Ch 1 (C-Channel based, T-Time based)
87CH2SN := T Data Sync Ch 2 (C-Channel based, T-Time based)
In this application, the backup channel uses time-based data synchronization.
This channel will become active only if the primary channel fails. Choose
Time Fall Back Mode 1. In the case of Channel 1 failure and absence of
required time sources for Channel 2, the 87L function is effectively inhibited
for all relays of the differential system.
87TFB := 1 Time Fall Back Mode (1–4)
To Next Page
Loading...
