GE 850 - Page 277

CHAPTER 6: PROTECTION SETPOINTS CURRENT ELEMENTS
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 6–9
I
2
T CURVES
The curves for the I
2
t are derived from the formula:
Where:
T = operate time (in seconds)
TDM = Multiplier setting
I = input current
I
pickup
= Pickup Current setting
T
RESET
= reset time in seconds (assuming energy capacity is 100% and RESET is
“Timed”)
Table 6-10: I
2
T CURVE TRIP TIMES (IN SECONDS)
IAC VERY INVERSE
0.5 1.451 0.656 0.269 0.172 0.133 0.113 0.101 0.093 0.087 0.083
1.0 2.901 1.312 0.537 0.343 0.266 0.227 0.202 0.186 0.174 0.165
2.0 5.802 2.624 1.075 0.687 0.533 0.453 0.405 0.372 0.349 0.331
4.0 11.605 5.248 2.150 1.374 1.065 0.906 0.810 0.745 0.698 0.662
6.0 17.407 7.872 3.225 2.061 1.598 1.359 1.215 1.117 1.046 0.992
8.0 23.209 10.497 4.299 2.747 2.131 1.813 1.620 1.490 1.395 1.323
10.0 29.012 13.121 5.374 3.434 2.663 2.266 2.025 1.862 1.744 1.654
IAC INVERSE
0.5 0.578 0.375 0.266 0.221 0.196 0.180 0.618 0.160 0.154 0.148
1.0 1.155 0.749 0.532 0.443 0.392 0.360 0.337 0.320 0.307 0.297
2.0 2.310 1.499 1.064 0.885 0.784 0.719 0.674 0.640 0.614 0.594
4.0 4.621 2.997 2.128 1.770 1.569 1.439 1.348 1.280 1.229 1.188
6.0 6.931 4.496 3.192 2.656 2.353 2.158 2.022 1.921 1.843 1.781
8.0 9.242 5.995 4.256 3.541 3.138 2.878 2.695 2.561 2.457 2.375
10.0 11.552 7.494 5.320 4.426 3.922 3.597 3.369 3.201 3.072 2.969
IAC SHORT INVERSE
0.5 0.072 0.047 0.035 0.031 0.028 0.027 0.026 0.026 0.025 0.025
1.0 0.143 0.095 0.070 0.061 0.057 0.054 0.052 0.051 0.050 0.049
2.0 0.286 0.190 0.140 0.123 0.114 0.108 0.105 0.102 0.100 0.099
4.0 0.573 0.379 0.279 0.245 0.228 0.217 0.210 0.204 0.200 0.197
6.0 0.859 0.569 0.419 0.368 0.341 0.325 0.314 0.307 0.301 0.296
8.0 1.145 0.759 0.559 0.490 0.455 0.434 0.419 0.409 0.401 0.394
10.0 1.431 0.948 0.699 0.613 0.569 0.542 0.524 0.511 0.501 0.493
MULTIPLIER
(TDM)
CURRENT (I/I
pickup
)
1.5 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
MULTIPLIER
(TDM)
CURRENT (I/I
pickup
)
1.5 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
0.01 0.44 0.25 0.11 0.06 0.04 0.03 0.02 0.02 0.01 0.01
0.10 4.44 2.50 1.11 0.63 0.40 0.28 0.20 0.16 0.12 0.10
1.00 44.44 25.00 11.11 6.25 4.00 2.78 2.04 1.56 1.23 1.00