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5 SETPOINTS
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:
where: T = trip time (seconds); M = multiplier value; I = input current; I
A, B, C, D, E = constants
Table 5–5: ANSI CURVE CONSTANTS
ANSI CURVE SHAPE
ANSI Extremely Inverse
ANSI Very Inverse
ANSI Normally Inverse
ANSI Moderately Inverse
Table 5–6: ANSI CURVE TRIP TIMES (IN SECONDS)
MULTIPLIER
(TDM)
1.5
ANSI EXTREMELY INVERSE
0.5
2.000
1.0
4.001
2.0
8.002
4.0
16.004
6.0
24.005
8.0
32.007
10.0
40.009
ANSI VERY INVERSE
0.5
1.567
1.0
3.134
2.0
6.268
4.0
12.537
6.0
18.805
8.0
25.073
10.0
31.341
ANSI NORMALLY INVERSE
0.5
2.142
1.0
4.284
2.0
8.568
4.0
17.137
6.0
25.705
8.0
34.274
10.0
42.842
ANSI MODERATELY INVERSE
0.5
0.675
1.0
1.351
2.0
2.702
4.0
5.404
6.0
8.106
8.0
10.807
10.0
13.509
GE Multilin
Courtesy of NationalSwitchgear.com
⎛
B
T
M
×
⎜
A
--------------------------- -
=
+
+
⎝
(
⁄
) C
I I
–
pu
A
0.0399
0.2294
0.0615
0.7989
0.0274
2.2614
0.1735
0.6791
2.0
3.0
4.0
0.872
0.330
0.184
1.744
0.659
0.368
3.489
1.319
0.736
6.977
2.638
1.472
10.466
3.956
2.208
13.955
5.275
2.944
17.443
6.594
3.680
0.663
0.268
0.171
1.325
0.537
0.341
2.650
1.074
0.682
5.301
2.148
1.365
7.951
3.221
2.047
10.602
4.295
2.730
13.252
5.369
3.412
0.883
0.377
0.256
1.766
0.754
0.513
3.531
1.508
1.025
7.062
3.016
2.051
10.594
4.524
3.076
14.125
6.031
4.102
17.656
7.539
5.127
0.379
0.239
0.191
0.757
0.478
0.382
1.515
0.955
0.764
3.030
1.910
1.527
4.544
2.866
2.291
6.059
3.821
3.054
7.574
4.776
3.818
750/760 Feeder Management Relay
D
E
---------------------------------- -
---------------------------------- -
+
2
3
(
(
⁄
) C
)
(
(
⁄
) C
)
I I
I I
–
–
pu
pu
= pickup current setpoint
pickup
B
C
D
0.5000
3.0094
0.3400
–0.2840
0.3000
–4.1899
0.8000
–0.0800
CURRENT ( I / I
)
pickup
5.0
6.0
7.0
0.124
0.093
0.075
0.247
0.185
0.149
0.495
0.371
0.298
0.990
0.742
0.596
1.484
1.113
0.894
1.979
1.483
1.192
2.474
1.854
1.491
0.130
0.108
0.094
0.260
0.216
0.189
0.520
0.432
0.378
1.040
0.864
0.755
1.559
1.297
1.133
2.079
1.729
1.510
2.599
2.161
1.888
0.203
0.172
0.151
0.407
0.344
0.302
0.814
0.689
0.604
1.627
1.378
1.208
2.441
2.067
1.812
3.254
2.756
2.415
4.068
3.445
3.019
0.166
0.151
0.141
0.332
0.302
0.281
0.665
0.604
0.563
1.329
1.208
1.126
1.994
1.812
1.689
2.659
2.416
2.252
3.324
3.020
2.815
5.6 S5 PROTECTION
⎞
⎟
⎠
E
0.7222
4.0505
9.1272
0.1271
8.0
9.0
0.063
0.055
0.126
0.110
0.251
0.219
0.503
0.439
0.754
0.658
1.006
0.878
1.257
1.097
0.085
0.078
0.170
0.156
0.340
0.312
0.680
0.625
1.020
0.937
1.360
1.250
1.700
1.562
0.135
0.123
0.270
0.246
0.541
0.492
1.082
0.983
1.622
1.475
2.163
1.967
2.704
2.458
0.133
0.128
0.267
0.255
0.533
0.511
1.066
1.021
1.600
1.532
2.133
2.043
2.666
2.554
(EQ 5.2)
10.0
0.049
5
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
2.465
5-33
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