GE Multilin 850

4–116 850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
PROTECTION CHAPTER 4: SETPOINTS
t
r
= characteristic constant
Table 4-27: ANSI INVERSE TIME CURVE CONSTANTS
Table 4-28: ANSI CURVE TRIP TIMES (IN SECONDS)
IEC CURVES
For European applications, the relay offers three standard curves defined in IEC 255-4 and
British standard BS142. These are defined as IEC Curve A, IEC Curve B, and IEC Curve C. The
formula for these curves is:
ANSI CURVE SHAPE A B C D E t
r
ANSI Extremely Inverse 0.0399 0.2294 0.5000 3.0094 0.7222 5.67
ANSI Very Inverse 0.0615 0.7989 0.3400 -0.2840 4.0505 3.88
ANSI Normally Inverse 0.0274 2.2614 0.3000 -4.1899 9.1272 5.95
ANSI Moderately Inverse 0.1735 0.6791 0.8000 -0.0800 0.1271 1.08
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