GE Multilin 750/760 Feeder Management Relay 5-33
5 SETPOINTS 5.6 S5 PROTECTION
5
ANSI CURVES:
The ANSI time overcurrent curve shapes conform to industry standards and the ANSI C37.90 curve classifications for
extremely, very, and moderately inverse. The ANSI curves are derived from the following formula:
(EQ 5.2)
where: T = trip time (seconds); M = multiplier value; I = input current; I
pickup
= pickup current setpoint
A, B, C, D, E = constants
Table 5–5: ANSI CURVE CONSTANTS
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
Table 5–6: ANSI CURVE TRIP TIMES (IN SECONDS)
MULTIPLIER
(TDM)
CURRENT ( I / I
pickup
)
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
TMA
B
II
pu
⁄()C–
--------------------------- -
D
II
pu
⁄()C–()
2
-----------------------------------
E
II
pu
⁄()C–()
3
-----------------------------------++ +
⎝⎠
⎜⎟
⎛⎞
×=
Courtesy of NationalSwitchgear.com
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