P.3.313
Date Code 20151029 Protection Manual SEL-411L Relay
Protection Functions
87L Channel Recorder
87L Channel Recorder
Line current differential schemes are easy to apply from a protection
perspective, but they may create application and event analysis challenges
related to the communications system. These systems often use devices (such
as relays, T1 multiplexers, and SONET backbones) from different
manufacturers. It is possible that some of these devices were never designed
for protection-grade applications. Most importantly, these devices contain no
instrumentation for troubleshooting line current differential applications used
with shared (multiplexed) channels.
(cc) Channel measurement—
delay in the receive direc-
tion
87CHpRXT (receive channel delay [ms]) used. Suppressed if !87CHpOK or
!(87TOK&ETLp).
(dd) Channel measurement—
asymmetry
87CHpAX (channel asymmetry [ms]) used. Suppressed if !87CHpOK or !(87TOK&ETLp).
Only for applications over time-based synchronized serial channels.
(ee) Channel measurement—
lost packet count (present
40-second measurement)
87CHpLX value used. Note that the 40-second lost packet count is only reset on a Group or
Port 87 setting change. Use the COM 87L C/R command to clear the 24 hour counter. This
command does not clear the 40-second counter.
(ff) Channel measurement—
lost packet count (24-hour
measurement)
The number of lost or defective packets during the last 24 hours (87CHpLD) recorded in
15-minute intervals. Use the COM 87L C/R command to clear the 24 hour counter. This
command does not clear the 40-second counter.
(gg) 24-hour lost packet count—
worst case since clearing
the record
Value and timestamp.
(ii) Channel measurement—
round-trip delay histogram
Only for applications over serial channels.
(jj) Channel measurement—
round-trip delay, worst case
since clearing the record
Only for applications over serial channels. Value and time stamp.
(kk) Channel measurement—
delay in the transmit direc-
tion, worst case since clear-
ing the record
Only for applications over time-based synchronized serial channels. Value and time stamp.
(ll) Channel measurement—
delay in the receive direc-
tion, worst case since clear-
ing the record
Only for applications over time-based synchronized serial channels (based on the E87CH and
87CHpSN settings). Value and time stamp.
(mm) Channel measurement—
channel asymmetry histo-
gram
Only for applications over time-based synchronized serial channels.
(nn) Channel measurement—
channel asymmetry, worst
case since clearing the
record
Value and time stamp.
(oo) Primary versus hot stand-by
channel usage
Reported only for 2SD applications. Percentages of time the primary and stand-by channels
were applied. Integrated runtime (87L enabled and !87LST and !ESTUB and !87TEST) when
87HSB is deasserted (primary channel used) and asserted (stand-by channel used).
(pp) Channel measurement—
receive delay histogram
Only for applications over Ethernet channels. Troubleshooting, testing, and on-going channel
monitoring.
Ta b l e 3.1 6 4 CO M 87 L Re p o r t Da t a I te m s (Sheet 4 of 4)
Data Item Description
NOTE: These channel recording
files are primarily intended for
internal SEL use.
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