# GE UR Series Instruction Manual Page 168

Line differential relay.

5.5 GROUPED ELEMENTS
IAC CURVES:
The curves for the General Electric type IAC relay family are derived from the formulae:
A
×
TDM
T
=
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 5–20: GE TYPE IAC INVERSE TIME CURVE CONSTANTS
IAC CURVE SHAPE
IAC EXTREME INVERSE
IAC VERY INVERSE
IAC INVERSE
IAC SHORT INVERSE
Table 5–21: IAC CURVE TRIP TIMES
MULTIPLIER
(TDM)
1.5
IAC EXTREMELY INVERSE
0.5
1.699
5
1.0
3.398
2.0
6.796
4.0
13.591
6.0
20.387
8.0
27.183
10.0
33.979
IAC VERY INVERSE
0.5
1.451
1.0
2.901
2.0
5.802
4.0
11.605
6.0
17.407
8.0
23.209
10.0
29.012
IAC INVERSE
0.5
0.578
1.0
1.155
2.0
2.310
4.0
4.621
6.0
6.931
8.0
9.242
10.0
11.552
IAC SHORT INVERSE
0.5
0.072
1.0
0.143
2.0
0.286
4.0
0.573
6.0
0.859
8.0
1.145
10.0
1.431
5-84
B
D
+
------------------------------- -
+
---------------------------------- -
2
I
I
--------------- - C
--------------- - C
I
I
pickup
pickup
TDM = Multiplier Setting
A to E = Constants
A
0.0040
0.0900
0.2078
0.0428
2.0
3.0
4.0
0.749
0.303
0.178
1.498
0.606
0.356
2.997
1.212
0.711
5.993
2.423
1.422
8.990
3.635
2.133
11.987
4.846
2.844
14.983
6.058
3.555
0.656
0.269
0.172
1.312
0.537
0.343
2.624
1.075
0.687
5.248
2.150
1.374
7.872
3.225
2.061
10.497
4.299
2.747
13.121
5.374
3.434
0.375
0.266
0.221
0.749
0.532
0.443
1.499
1.064
0.885
2.997
2.128
1.770
4.496
3.192
2.656
5.995
4.256
3.541
7.494
5.320
4.426
0.047
0.035
0.031
0.095
0.070
0.061
0.190
0.140
0.123
0.379
0.279
0.245
0.569
0.419
0.368
0.759
0.559
0.490
0.948
0.699
0.613
L90 Line Differential Relay
E
+
---------------------------------- -
T
3
I
--------------- - C
I
pickup
B
C
0.6379
0.6200
1.7872
0.7955
0.1000
–1.2885
0.8630
0.8000
–0.4180
0.0609
0.6200
–0.0010
CURRENT ( I / I
)
pickup
5.0
6.0
7.0
0.123
0.093
0.074
0.246
0.186
0.149
0.491
0.372
0.298
0.983
0.744
0.595
1.474
1.115
0.893
1.966
1.487
1.191
2.457
1.859
1.488
0.133
0.113
0.101
0.266
0.227
0.202
0.533
0.453
0.405
1.065
0.906
0.810
1.598
1.359
1.215
2.131
1.813
1.620
2.663
2.266
2.025
0.196
0.180
0.168
0.392
0.360
0.337
0.784
0.719
0.674
1.569
1.439
1.348
2.353
2.158
2.022
3.138
2.878
2.695
3.922
3.597
3.369
0.028
0.027
0.026
0.057
0.054
0.052
0.114
0.108
0.105
0.228
0.217
0.210
0.341
0.325
0.314
0.455
0.434
0.419
0.569
0.542
0.524
5 SETTINGS
t
r
--------------------------------- -
×
=
TDM
RESET
2
I
--------------- -
I
pickup
I = Input Current
t
= Characteristic Constant
r
D
E
T
R
0.2461
6.008
7.9586
4.678
0.1947
0.990
0.0221
0.222
8.0
9.0
10.0
0.062
0.053
0.046
0.124
0.106
0.093
0.248
0.212
0.185
0.495
0.424
0.370
0.743
0.636
0.556
0.991
0.848
0.741
1.239
1.060
0.926
0.093
0.087
0.083
0.186
0.174
0.165
0.372
0.349
0.331
0.745
0.698
0.662
1.117
1.046
0.992
1.490
1.395
1.323
1.862
1.744
1.654
0.160
0.154
0.148
0.320
0.307
0.297
0.640
0.614
0.594
1.280
1.229
1.188
1.921
1.843
1.781
2.561
2.457
2.375
3.201
3.072
2.969
0.026
0.025
0.025
0.051
0.050
0.049
0.102
0.100
0.099
0.204
0.200
0.197
0.307
0.301
0.296
0.409
0.401
0.394
0.511
0.501
0.493
GE Power Management
1

L90