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5.5 GROUPED ELEMENTS
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 formulae for these curves are:
where: T = operate time (in seconds), TDM = Multiplier setting, I = input current, I
constants, t
r
and
is "Timed")
RESET
Table 5–13: IEC (BS) INVERSE TIME CURVE CONSTANTS
IEC (BS) CURVE SHAPE
IEC Curve A (BS142)
IEC Curve B (BS142)
IEC Curve C (BS142)
IEC Short Inverse
Table 5–14: IEC CURVE TRIP TIMES (IN SECONDS)
MULTIPLIER
(TDM)
1.5
IEC CURVE A
0.05
0.860
5
0.10
1.719
0.20
3.439
0.40
6.878
0.60
10.317
0.80
13.755
1.00
17.194
IEC CURVE B
0.05
1.350
0.10
2.700
0.20
5.400
0.40
10.800
0.60
16.200
0.80
21.600
1.00
27.000
IEC CURVE C
0.05
3.200
0.10
6.400
0.20
12.800
0.40
25.600
0.60
38.400
0.80
51.200
1.00
64.000
IEC SHORT TIME
0.05
0.153
0.10
0.306
0.20
0.612
0.40
1.223
0.60
1.835
0.80
2.446
1.00
3.058
5-110
K
-------------------------------------- -
E
T
TDM
I I
=
–
pickup
= characteristic constant, and T
K
E
0.140
0.020
13.500
1.000
80.000
2.000
0.050
0.040
2.0
3.0
4.0
0.501
0.315
0.249
1.003
0.630
0.498
2.006
1.260
0.996
4.012
2.521
1.992
6.017
3.781
2.988
8.023
5.042
3.984
10.029
6.302
4.980
0.675
0.338
0.225
1.350
0.675
0.450
2.700
1.350
0.900
5.400
2.700
1.800
8.100
4.050
2.700
10.800
5.400
3.600
13.500
6.750
4.500
1.333
0.500
0.267
2.667
1.000
0.533
5.333
2.000
1.067
10.667
4.000
2.133
16.000
6.000
3.200
21.333
8.000
4.267
26.667
10.000
5.333
0.089
0.056
0.044
0.178
0.111
0.088
0.356
0.223
0.175
0.711
0.445
0.351
1.067
0.668
0.526
1.423
0.890
0.702
1.778
1.113
0.877
B90 Low Impedance Bus Differential System
t
r
-------------------------------------- -
,
T
TDM
1
=
1
I I
RESET
–
pickup
= reset time in seconds (assuming energy capacity is 100%
RESET
T
R
9.7
43.2
58.2
0.500
CURRENT ( I / I
)
pickup
5.0
6.0
0.214
0.192
0.428
0.384
0.856
0.767
1.712
1.535
2.568
2.302
3.424
3.070
4.280
3.837
0.169
0.135
0.338
0.270
0.675
0.540
1.350
1.080
2.025
1.620
2.700
2.160
3.375
2.700
0.167
0.114
0.333
0.229
0.667
0.457
1.333
0.914
2.000
1.371
2.667
1.829
3.333
2.286
0.038
0.034
0.075
0.067
0.150
0.135
0.301
0.269
0.451
0.404
0.602
0.538
0.752
0.673
5 SETTINGS
2
= Pickup Current setting, K, E =
pickup
7.0
8.0
9.0
0.176
0.165
0.156
0.353
0.330
0.312
0.706
0.659
0.623
1.411
1.319
1.247
2.117
1.978
1.870
2.822
2.637
2.493
3.528
3.297
3.116
0.113
0.096
0.084
0.225
0.193
0.169
0.450
0.386
0.338
0.900
0.771
0.675
1.350
1.157
1.013
1.800
1.543
1.350
2.250
1.929
1.688
0.083
0.063
0.050
0.167
0.127
0.100
0.333
0.254
0.200
0.667
0.508
0.400
1.000
0.762
0.600
1.333
1.016
0.800
1.667
1.270
1.000
0.031
0.029
0.027
0.062
0.058
0.054
0.124
0.115
0.109
0.247
0.231
0.218
0.371
0.346
0.327
0.494
0.461
0.435
0.618
0.576
0.544
(EQ 5.6)
10.0
0.149
0.297
0.594
1.188
1.782
2.376
2.971
0.075
0.150
0.300
0.600
0.900
1.200
1.500
0.040
0.081
0.162
0.323
0.485
0.646
0.808
0.026
0.052
0.104
0.207
0.311
0.415
0.518
GE Multilin
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