GE 850 Instruction Manual page 276

CURRENT ELEMENTS
Table 6-9: IAC CURVE TRIP TIMES (IN SECONDS)
MULTIPLIER CURRENT (I/I
(TDM)
1.5
IAC EXTREMELY INVERSE
0.5 1.699
1.0 3.398
2.0 6.796
4.0 13.591
6.0 20.387
8.0 27.183
10.0 33.979
6–8
MULTIPLIER CURRENT (I/I
(TDM)
1.5 2.0
0.60 38.400 16.000 6.000
0.80 51.200 21.333 8.000
1.00 64.000 26.667 10.000 5.333
IEC SHORT INVERSE
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
IAC CURVES
The curves for the General Electric type IAC relay family are derived from the formula:
Where:
T = operate time (in seconds)
TDM = Multiplier setting
I = input current
I = Pickup Current setting
pickup
A to E = constants
t = characteristic constant
r
T = reset time in seconds (assuming energy capacity is 100% and RESET is
RESET
"Timed")
Table 6-8: GE TYPE IAC INVERSE TIME CURVE CONSTANTS
IAC CURVE SHAPE A
IAC Extremely Inverse 0.0040
IAC Very Inverse 0.0900
IAC Inverse 0.2078
IAC Short Inverse 0.0428
)
pickup
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
)
pickup
3.0 4.0 5.0
3.200 2.000
4.267 2.667
3.333
0.056 0.044 0.038
0.111 0.088 0.075
0.223 0.175 0.150
0.445 0.351 0.301
0.668 0.526 0.451
0.890 0.702 0.602
1.113 0.877 0.752
B C
0.6379 0.6200
0.7965 0.1000
0.8630 0.8000
0.0609 0.6200
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
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 6: PROTECTION SETPOINTS
6.0 7.0 8.0 9.0
1.371 1.000 0.762 0.600
1.829 1.333 1.016 0.800
2.286 1.667 1.270 1.000
0.034 0.031 0.029 0.027
0.067 0.062 0.058 0.054
0.135 0.124 0.115 0.109
0.269 0.247 0.231 0.218
0.404 0.371 0.346 0.327
0.538 0.494 0.461 0.435
0.673 0.618 0.576 0.544
D E
1.7872 0.2461
-1.2885 7.9586
-0.4180 0.1947
-0.0010 0.0221
8.0 9.0
0.062 0.053
0.124 0.106
0.248 0.212
0.495 0.424
0.743 0.636
0.991 0.848
1.239 1.060
10.0
0.485
0.646
0.808
0.026
0.052
0.104
0.207
0.311
0.415
0.518
t
r
6.008
4.678
0.990
0.222
10.0
0.046
0.093
0.185
0.370
0.556
0.741
0.926