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S3 PROTECTION
6–68
Multiplier (TDM)
Current (I/Ipickup)
1.5
8.0
34.274 14.125 6.031
10.0
42.842 17.656 7.539
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 6.059
10.0
13.509 7.574
IEC Curves
For European applications, the relay offers the four standard curves defined in IEC 255-4
and British standard BS142. These are defined as IEC Curve A, IEC Curve B, IEC Curve C, and
Short Inverse. The formulae for these curves are:
where: T = trip time (seconds), M = multiplier setpoint, I = input current, I
setpoint, K, E = constants.
Table 6-5: 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 6-6: IEC Curve Trip Times (in seconds)
Multiplier (TDM)
Current (I/Ipickup)
1.5
2.0
IEC Curve A
0.05
0.860
0.501
0.10
1.719
1.003
0.20
3.439
2.006
0.40
6.878
4.012
0.60
10.317 6.017
0.80
13.755 8.023
1.00
17.194 10.029 6.302
IEC Curve B
0.05
1.350
0.675
0.10
2.700
1.350
0.20
5.400
2.700
0.40
10.800 5.400
0.60
16.200 8.100
0.80
21.600 10.800 5.400
2.0
3.0
4.0
5.0
4.102
3.254
5.127
4.068
0.379
0.239
0.191
0.166
0.757
0.478
0.382
0.332
1.515
0.955
0.764
0.665
3.030
1.910
1.527
1.329
4.544
2.866
2.291
1.994
3.821
3.054
2.659
4.776
3.818
3.324
K
0.140
13.500
80.000
0.050
3.0
4.0
5.0
0.315
0.249
0.214
0.630
0.498
0.428
1.260
0.996
0.856
2.521
1.992
1.712
3.781
2.988
2.568
5.042
3.984
3.424
4.980
4.280
0.338
0.225
0.169
0.675
0.450
0.338
1.350
0.900
0.675
2.700
1.800
1.350
4.050
2.700
2.025
3.600
2.700
339 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 6: SETPOINTS
6.0
7.0
8.0
9.0
2.756
2.415
2.163
1.967
3.445
3.019
2.704
2.458
0.151
0.141
0.133
0.128
0.302
0.281
0.267
0.255
0.604
0.563
0.533
0.511
1.208
1.126
1.066
1.021
1.812
1.689
1.600
1.532
2.416
2.252
2.133
2.043
3.020
2.815
2.666
2.554
= pickup current
pu
E
0.020
1.000
2.000
0.040
6.0
7.0
8.0
9.0
0.192
0.176
0.165
0.156
0.384
0.353
0.330
0.312
0.767
0.706
0.659
0.623
1.535
1.411
1.319
1.247
2.302
2.117
1.978
1.870
3.070
2.822
2.637
2.493
3.837
3.528
3.297
3.116
0.135
0.113
0.096
0.084
0.270
0.225
0.193
0.169
0.540
0.450
0.386
0.338
1.080
0.900
0.771
0.675
1.620
1.350
1.157
1.013
2.160
1.800
1.543
1.350
10.0
1.808
2.260
0.123
0.247
0.493
0.986
1.479
1.972
2.465
Eq. 18
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
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