# GE UR Series Instruction Manual Page 167

Line differential relay.

5 SETTINGS
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:
K
----------------------------------
×
E
T
TDM
I
=
--------------- -
I
pickup
where: T = Operate Time (sec.)
I
= Pickup Current Setting
pickup
T
= Reset Time in sec. (assuming energy capacity is 100% and RESET: Timed)
RESET
Table 5–18: 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 5–19: IEC CURVE TRIP TIMES (IN SECONDS)
MULTIPLIER
(TDM)
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
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
1.00
27.000
13.500
IEC CURVE C
0.05
3.200
1.333
0.10
6.400
2.667
0.20
12.800
5.333
0.40
25.600
10.667
0.60
38.400
16.000
0.80
51.200
21.333
1.00
64.000
26.667
IEC SHORT TIME
0.05
0.153
0.089
0.10
0.306
0.178
0.20
0.612
0.356
0.40
1.223
0.711
0.60
1.835
1.067
0.80
2.446
1.423
1.00
3.058
1.778
GE Power Management
×
T
TDM
=
1
RESET
TDM = Multiplier Setting
K , E = Constants
K
E
0.140
0.020
13.500
1.000
80.000
2.000
0.050
0.040
CURRENT ( I / I
3.0
4.0
0.315
0.249
0.630
0.498
1.260
0.996
2.521
1.992
3.781
2.988
5.042
3.984
6.302
4.980
0.338
0.225
0.675
0.450
1.350
0.900
2.700
1.800
4.050
2.700
5.400
3.600
6.750
4.500
0.500
0.267
1.000
0.533
2.000
1.067
4.000
2.133
6.000
3.200
8.000
4.267
10.000
5.333
0.056
0.044
0.111
0.088
0.223
0.175
0.445
0.351
0.668
0.526
0.890
0.702
1.113
0.877
L90 Line Differential Relay
t
r
--------------------------------- -
2
I
--------------- -
1
I
pickup
I = Input Current
t
= Characteristic Constant
r
T
R
9.7
43.2
58.2
0.500
)
pickup
5.0
6.0
7.0
0.214
0.192
0.176
0.428
0.384
0.353
0.856
0.767
0.706
1.712
1.535
1.411
2.568
2.302
2.117
3.424
3.070
2.822
4.280
3.837
3.528
0.169
0.135
0.113
0.338
0.270
0.225
0.675
0.540
0.450
1.350
1.080
0.900
2.025
1.620
1.350
2.700
2.160
1.800
3.375
2.700
2.250
0.167
0.114
0.083
0.333
0.229
0.167
0.667
0.457
0.333
1.333
0.914
0.667
2.000
1.371
1.000
2.667
1.829
1.333
3.333
2.286
1.667
0.038
0.034
0.031
0.075
0.067
0.062
0.150
0.135
0.124
0.301
0.269
0.247
0.451
0.404
0.371
0.602
0.538
0.494
0.752
0.673
0.618
5.5 GROUPED ELEMENTS
8.0
9.0
10.0
0.165
0.156
0.149
0.330
0.312
0.297
0.659
0.623
0.594
1.319
1.247
1.188
1.978
1.870
1.782
2.637
2.493
2.376
3.297
3.116
2.971
0.096
0.084
0.075
0.193
0.169
0.150
0.386
0.338
0.300
0.771
0.675
0.600
1.157
1.013
0.900
1.543
1.350
1.200
1.929
1.688
1.500
0.063
0.050
0.040
0.127
0.100
0.081
0.254
0.200
0.162
0.508
0.400
0.323
0.762
0.600
0.485
1.016
0.800
0.646
1.270
1.000
0.808
0.029
0.027
0.026
0.058
0.054
0.052
0.115
0.109
0.104
0.231
0.218
0.207
0.346
0.327
0.311
0.461
0.435
0.415
0.576
0.544
0.518
5-83
5

L90