Sel 411L - Page 429

P.3.321
Date Code 20151029 Protection Manual SEL-411L Relay
Protection Functions
Protection Application Examples
The relay sends data at the rate of 64 kb/s (multiplexer rates may be faster). A
healthy channel should have a bit error rate (BER) of less than 10
-4
(or 1 in
10000 bits). Assuming that errors are uniformly distributed, we can calculate
lost bits over a 40-second period: 262 lost bits. When the
relay detects a bit error, the relay rejects the whole packet, not just the bit.
Therefore, the number of lost packets equals the number of lost bits. Set the
lost packet alarm threshold to 262.
87CH1PC := 262 Ch 1 Lost Packet Alarm Thres. (OFF, 1–2500)
87CH2PC := 262 Ch 2 Lost Packet Alarm Thres. (OFF, 1–2500)
Group Settings
Line Configuration
In this application, CTs at the same terminal have the same CT ratios (see
Table 1).
We would have the following at terminal S:
CTRW := 320 Current Transformer Ratio—Input W (1–50000)
CTRX := 320 Current Transformer Ratio—Input X (1–50000)
We would have the following at terminal R:
CTRW := 400 Current Transformer Ratio—Input W (1–50000)
CTRX := 400 Current Transformer Ratio—Input X (1–50000)
Enter the PT ratio and nominal secondary voltage according to Table 3.166.
We would have the following at both terminals:
PTRY := 4500 Potential Transformer Ratio—Input Y (1.0–10000)
VNOMY := 111 PT Nominal Voltage (L-L)—Input Y (60–300 V, sec)
Enter the secondary impedances according to Figure 3.219.
Relay S:
Z1MAG := 2.514 Pos.-Seq. Line Impedance Mag. (0.05–255 , sec)
Z1ANG := 9.602 Pos.-Seq. Line Impedance Angle (5.00–90°)
Z0MAG := 8.39 Zero-Seq. Line Impedance Mag. (0.05–255 , sec)
Z0ANG := 5.20 Zero-Seq. Line Impedance Angle (5.00–90°)
Relay R:
Z1MAG := 3.143 Pos.-Seq. Line Impedance Mag. (0.05–255 , sec)
Z1ANG := 12.002 Pos.-Seq. Line Impedance Angle (5.00–90°)
Z0MAG := 6.71 Zero-Seq. Line Impedance Mag. (0.05–255 , sec)
Z0ANG := 5.00 Zero-Seq. Line Impedance Angle (5.00–90°)
Relay Configuration
Enable the 87L elements. We would have the following at both terminals:
E87L := Y Enable 87L Function (Y, N)
64 1024 40• •
10000
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