Sel 411L - Figure 3.219 Channel Report During Commissioning Testing

P.3.320
SEL-411L Relay Protection Manual Date Code 20151029
Protection Functions
Protection Application Examples
87 Channel Monitoring
Choose channel monitoring settings based on the expected characteristics of
the particular channel. For example, assume that the channel report (use the
COM 87L command) during commissioning of this application displays the
values in Figure 3.219.
Channel round trip delay
Delay [ms] Ch. 1 [%] Ch. 2 [%]
0-2 97.2 0.8
2-4 2.5 98.1
4-6 0.3 1.1
6-8 0.0 0.0
8-10 0.0 0.0
10-12 0.0 0.0
12-15 0.0 0.0
15-20 0.0 0.0
20-30 0.0 0.0
30+ 0.0 0.0
Channel asymmetry
Asymm [ms] Ch. 1 [%] Ch. 2 [%]
0.00-0.25 99.8 95.4
0.25-0.50 0.2 4.6
0.50-0.75 0.0 0.0
0.75-1.00 0.0 0.0
1.00-1.50 0.0 0.0
1.50-2.00 0.0 0.0
2.00-3.00 0.0 0.0
3.00-4.00 0.0 0.0
4.00-5.00 0.0 0.0
5.00+ 0.0 0.0
Figure 3.219 Channel Report During Commissioning Testing
From the report, we see that round-trip delay for Channel 1 is in the range of
0–2 ms (97.2 percent) and in the range of 2–4 ms (98.1 percent) for Channel 2.
Set the Max Round Trip Delay setting to 4 ms for Channel 1 and to 6 ms for
Channel 2.
Channel asymmetry is low for both channels (in the 0.00–0.25 ms range). A
step change in channel delay can be attributed to channel switching. Set the
maximum step change delay to a low value (3 ms) to detect this event. The
87L characteristic settings can accommodate asymmetry of between 1 ms and
4 ms. Experience has shown that channel asymmetry could be an issue on
SONET networks, and we need to set the allowable asymmetry longer on
Channel 2 than on Channel 1. Set the maximum allowable asymmetry to 1 ms
on Channel 1 and to 4 ms on Channel 2.
We would have the following at both terminals:
87CH1MT := 4 Max. Round Trip Delay for Ch 1 (OFF, 1.0–50 ms)
87CH1MD := 3 Max. Step Change in Ch 1 Delay (OFF, 3.0–50 ms)
87CH1MA := 1 Max. Allowable Asym. for Ch 1 (OFF, 0.2–10 ms)
87CH2MT := 6 Max. Round Trip Delay for Ch 2 (OFF, 1.0–50 ms)
87CH2MD := 3 Max. Step Change in Ch 2 Delay (OFF, 3.0–50 ms)
87CH2MA := 4 Max. Allowable Asym. for Ch 2 (OFF, 0.2–10 ms)
Configure the 87L recorder to trigger for a channel alarm or a differential
operation.
87CHTRG := 87OP 87L Recording Trigger (SEL
OGIC control equation)
Many records will not be of interest, so disable write protect.
87CHWP := N Enable Write Protect 87L Recording Files (Y,N)