Schweitzer Engineering Laboratories SEL-787 - Table 4.14 Equations Associated with U.S. Curves; Table 4.15 Equations Associated with IEC Curves

4.38
SEL-787 Relay Instruction Manual Date Code 20081022
Protection and Logic Functions
Basic Protection
Table 4.14 Equations Associated With U.S. Curves
Curve Type Operating Time Reset Time Figure
U1 (Moderately Inverse) Figure 4.19
U2 (Inverse)
Figure 4.20
U3 (Very Inverse)
Figure 4.21
U4 (Extremely Inverse)
Figure 4.22
U5 (Short-Time Inverse)
Figure 4.23
Table 4.15 Equations Associated With IEC Curves
Curve Type Operating Time Reset Time Figure
C1 (Standard Inverse) Figure 4.24
C2 (Very Inverse)
Figure 4.25
C3 (Extremely Inverse)
Figure 4.26
C4 (Long-Time Inverse)
Figure 4.27
C5 (Short-Time Inverse)
Figure 4.28
t
p
TD 0.0226
0.0104
M
0.02
1–
----------------------+
⎝⎠
⎛⎞
• =t
r
TD
1.08
1M
2
–
----------------
⎝⎠
⎛⎞
• =
t
p
TD 0.180
5.95
M
2
1–
----------------+
⎝⎠
⎛⎞
• =t
r
TD
5.95
1M
2
–
----------------
⎝⎠
⎛⎞
• =
t
p
TD 0.0963
3.88
M
2
1–
----------------+
⎝⎠
⎛⎞
• =t
r
TD
3.88
1M
2
–
----------------
⎝⎠
⎛⎞
• =
t
p
TD 0.0352
5.67
M
2
1–
----------------+
⎝⎠
⎛⎞
• =
t
r
TD
5.67
1M
2
–
----------------
⎝⎠
⎛⎞
• =
t
p
TD 0.00262
0.00342
M
0.02
1–
----------------------+
⎝⎠
⎛⎞
• =t
r
TD
0.323
1M
2
–
----------------
⎝⎠
⎛⎞
• =
t
p
TD
0.14
M
0.02
1–
----------------------
⎝⎠
⎛⎞
• =t
r
TD
13.5
1M
2
–
----------------
⎝⎠
⎛⎞
• =
t
p
TD
13.5
M1–
--------------
⎝⎠
⎛⎞
• =t
r
TD
47.3
1M
2
–
----------------
⎝⎠
⎛⎞
• =
t
p
TD
80
M
2
1–
----------------
⎝⎠
⎛⎞
• =t
r
TD
80
1M
2
–
----------------
⎝⎠
⎛⎞
• =
t
p
TD
120
M1–
--------------
⎝⎠
⎛⎞
• =
t
r
TD
120
1M–
--------------
⎝⎠
⎛⎞
• =
t
p
TD
0.05
M
0.04
1–
----------------------
⎝⎠
⎛⎞
• =t
r
TD
4.85
1M
2
–
----------------
⎝⎠
⎛⎞
• =