CHAPTER 6: SETPOINTS
S3 PROTECTION
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
6–33
Table 6-3: ANSI Curve Constants
Table 6-4: ANSI Curve Trip Times (in seconds)
IEC Curves
ANSI Curve Shape
A
B
C
D
E
ANSI Extremely Inverse
0.0399
0.2294
0.5000
3.0094
0.7222
ANSI Very Inverse
0.0615
0.7989
0.3400
–0.2840
4.0505
ANSI Normally Inverse
0.0274
2.2614
0.3000
–4.1899
9.1272
ANSI Moderately Inverse
0.1735
0.6791
0.8000
–0.0800
0.1271
Multiplier (TDM)
Current (I/Ipickup)
1.5
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
ANSI Extremely Inverse
0.5
2.000 0.872 0.330 0.184 0.124 0.093 0.075 0.063 0.055 0.049
1.0
4.001 1.744 0.659 0.368 0.247 0.185 0.149 0.126 0.110 0.098
2.0
8.002 3.489 1.319 0.736 0.495 0.371 0.298 0.251 0.219 0.196
4.0
16.004 6.977 2.638 1.472 0.990 0.742 0.596 0.503 0.439 0.393
6.0
24.005 10.466 3.956 2.208 1.484 1.113 0.894 0.754 0.658 0.589
8.0
32.007 13.955 5.275 2.944 1.979 1.483 1.192 1.006 0.878 0.786
10.0
40.009 17.443 6.594 3.680 2.474 1.854 1.491 1.257 1.097 0.982
ANSI Very Inverse
0.5
1.567 0.663 0.268 0.171 0.130 0.108 0.094 0.085 0.078 0.073
1.0
3.134 1.325 0.537 0.341 0.260 0.216 0.189 0.170 0.156 0.146
2.0
6.268 2.650 1.074 0.682 0.520 0.432 0.378 0.340 0.312 0.291
4.0
12.537 5.301 2.148 1.365 1.040 0.864 0.755 0.680 0.625 0.583
6.0
18.805 7.951 3.221 2.047 1.559 1.297 1.133 1.020 0.937 0.874
8.0
25.073 10.602 4.295 2.730 2.079 1.729 1.510 1.360 1.250 1.165
10.0
31.341 13.252 5.369 3.412 2.599 2.161 1.888 1.700 1.562 1.457
ANSI Normally Inverse
0.5
2.142 0.883 0.377 0.256 0.203 0.172 0.151 0.135 0.123 0.113
1.0
4.284 1.766 0.754 0.513 0.407 0.344 0.302 0.270 0.246 0.226
2.0
8.568 3.531 1.508 1.025 0.814 0.689 0.604 0.541 0.492 0.452
4.0
17.137 7.062 3.016 2.051 1.627 1.378 1.208 1.082 0.983 0.904
6.0
25.705 10.594 4.524 3.076 2.441 2.067 1.812 1.622 1.475 1.356
8.0
34.274 14.125 6.031 4.102 3.254 2.756 2.415 2.163 1.967 1.808
10.0
42.842 17.656 7.539 5.127 4.068 3.445 3.019 2.704 2.458 2.260
ANSI Moderately Inverse
0.5
0.675 0.379 0.239 0.191 0.166 0.151 0.141 0.133 0.128 0.123
1.0
1.351 0.757 0.478 0.382 0.332 0.302 0.281 0.267 0.255 0.247
2.0
2.702 1.515 0.955 0.764 0.665 0.604 0.563 0.533 0.511 0.493
4.0
5.404 3.030 1.910 1.527 1.329 1.208 1.126 1.066 1.021 0.986
6.0
8.106 4.544 2.866 2.291 1.994 1.812 1.689 1.600 1.532 1.479
8.0
10.807 6.059 3.821 3.054 2.659 2.416 2.252 2.133 2.043 1.972
10.0
13.509 7.574 4.776 3.818 3.324 3.020 2.815 2.666 2.554 2.465