GE D90 Plus - Page 243

CHAPTER 7: PROTECTION GROUPED PROTECTION ELEMENTS
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 233
IAC curves
The curves for the General Electric type IAC relay family are derived from the formulae:
Eq. 14
Eq. 15
where
• T
operate
= operate time (in seconds)
• TDM = multiplier setting
• I = input current
• I
pickup
= pickup current setting
• A to E = constants defined in the table
• T
reset
= reset time in seconds (assuming the energy capacity is 100% and the reset
mode is “Timed”)
• t
r
= characteristic constant defined in the table
Table 10: GE type IAC inverse time curve constants
Table 11: GE type IAC curve trip times (in seconds)
IAC curve shape ABCDEt
r
IAC Extreme Inverse 0.0040 0.6379 0.6200 1.7872 0.2461 6.008
IAC Very Inverse 0.0900 0.7955 0.1000 –1.2885 7.9586 4.678
IAC Inverse 0.2078 0.8630 0.8000 –0.4180 0.1947 0.990
IAC Short Inverse 0.0428 0.0609 0.6200 –0.0010 0.0221 0.222
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
IAC Extremely Inverse
0.5 1.699 0.749 0.303 0.178 0.123 0.093 0.074 0.062 0.053 0.046
1.0 3.398 1.498 0.606 0.356 0.246 0.186 0.149 0.124 0.106 0.093
2.0 6.796 2.997 1.212 0.711 0.491 0.372 0.298 0.248 0.212 0.185
4.0 13.591 5.993 2.423 1.422 0.983 0.744 0.595 0.495 0.424 0.370
6.0 20.387 8.990 3.635 2.133 1.474 1.115 0.893 0.743 0.636 0.556
8.0 27.183 11.987 4.846 2.844 1.966 1.487 1.191 0.991 0.848 0.741
10.0 33.979 14.983 6.058 3.555 2.457 1.859 1.488 1.239 1.060 0.926
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 0.168 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
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