GE 745 Instruction Manual page 156

S4 ELEMENTS
5–60
ANSI curves:
The ANSI TOC shapes conform to industry standards and the ANSI C37.90 curve
classifications for extremely, very, normally, and moderately inverse shapes. The ANSI
curves are derived from the formula below, where 1.03
T M × A ----------------------------- -
= +
I I ⁄
where: T = operate time (in seconds), M = multiplier setpoint, I = input current
I = pickup current setpoint, and A, B, C, D, E = constants
pickup
ANSI curve shape
ANSI extremely inverse
ANSI very inverse
ANSI normally inverse
ANSI moderately inverse
Table 5–5: ANSI curve trip times (in seconds)
TDM
1.5 2.0
0.5 2.000 0.872
1.0 4.001 1.744
2.0 8.002 3.489
4.0 16.004 6.977
6.0 24.005 10.466
8.0 32.007 13.955
10.0 40.009 17.443
0.5 1.567 0.663
1.0 3.134 1.325
2.0 6.268 2.650
4.0 12.537 5.301
6.0 18.805 7.951
8.0 25.073 10.602
10.0 31.341 13.252
0.5 2.142 0.883
1.0 4.284 1.766
2.0 8.568 3.531
4.0 17.137 7.062
6.0 25.705 10.594
8.0 34.274 14.125
10.0 42.842 17.656
0.5 0.675 0.379
1.0 1.351 0.757
2.0 2.702 1.515
4.0 5.404 3.030
6.0 8.106 4.544
8.0 10.807 6.059
B D
------------------------------------- -
+
2
C
( I I ⁄ C )
– –
pickup
pickup
Table 5–4: ANSI curve constants
A B
0.0399 0.2294
0.0615 0.7989
0.0274 2.2614
0.1735 0.6791
Current ( I / I
pickup
3.0 4.0 5.0 6.0
ANSI Extremely Inverse
0.330 0.184 0.124 0.093
0.659 0.368 0.247 0.185
1.319 0.736 0.495 0.371
2.638 1.472 0.990 0.742
3.956 2.208 1.484 1.113
5.275 2.944 1.979 1.483
6.594 3.680 2.474 1.854
ANSI Very Inverse
0.268 0.171 0.130 0.108
0.537 0.341 0.260 0.216
1.074 0.682 0.520 0.432
2.148 1.365 1.040 0.864
3.221 2.047 1.559 1.297
4.295 2.730 2.079 1.729
5.369 3.412 2.599 2.161
ANSI Normally Inverse
0.377 0.256 0.203 0.172
0.754 0.513 0.407 0.344
1.508 1.025 0.814 0.689
3.016 2.051 1.627 1.378
4.524 3.076 2.441 2.067
6.031 4.102 3.254 2.756
7.539 5.127 4.068 3.445
ANSI Moderately Inverse
0.239 0.191 0.166 0.151
0.478 0.382 0.332 0.302
0.955 0.764 0.665 0.604
1.910 1.527 1.329 1.208
2.866 2.291 1.994 1.812
3.821 3.054 2.659 2.416
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETPOINTS
I / I 20.0:
≤ pickup <
E
------------------------------------- -
+
3
( I I ⁄ C )
–
pickup
C D
0.5000 3.0094
0.3400 –0.2840
0.3000 –4.1899
0.8000 –0.0800
)
7.0 8.0 9.0
0.075 0.063 0.055
0.149 0.126 0.110
0.298 0.251 0.219
0.596 0.503 0.439
0.894 0.754 0.658
1.192 1.006 0.878
1.491 1.257 1.097
0.094 0.085 0.078
0.189 0.170 0.156
0.378 0.340 0.312
0.755 0.680 0.625
1.133 1.020 0.937
1.510 1.360 1.250
1.888 1.700 1.562
0.151 0.135 0.123
0.302 0.270 0.246
0.604 0.541 0.492
1.208 1.082 0.983
1.812 1.622 1.475
2.415 2.163 1.967
3.019 2.704 2.458
0.141 0.133 0.128
0.281 0.267 0.255
0.563 0.533 0.511
1.126 1.066 1.021
1.689 1.600 1.532
2.252 2.133 2.043
(EQ 5.7)
E
0.7222
4.0505
9.1272
0.1271
10.0
0.049
0.098
0.196
0.393
0.589
0.786
0.982
0.073
0.146
0.291
0.583
0.874
1.165
1.457
0.113
0.226
0.452
0.904
1.356
1.808
2.260
0.123
0.247
0.493
0.986
1.479
1.972