CHAPTER 5: SETTINGS GROUPED ELEMENTSD30 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 5-2235IAC curvesThe curves for the General Electric type IAC relay family are derived from the formulae:Eq. 5-9whereT = operate time (in seconds)TDM = Multiplier settingI = Input currentIpkp = Pickup Current settingA to E = constants defined in the tabletr = characteristic constant defined in the tableTRESET = reset time in seconds (assuming energy capacity is 100% and RESET is “Timed”)Table 5-29: GE type IAC inverse time curve constantsTable 5-30: GE type IAC curve trip times1.00 3.058 1.778 1.113 0.877 0.752 0.673 0.618 0.576 0.544 0.518IAC curve shape A B C D E trIAC Extreme Inverse 0.0040 0.6379 0.6200 1.7872 0.2461 6.008IAC Very Inverse 0.0900 0.7955 0.1000 –1.2885 7.9586 4.678IAC Inverse 0.2078 0.8630 0.8000 –0.4180 0.1947 0.990IAC Short Inverse 0.0428 0.0609 0.6200 –0.0010 0.0221 0.222Multiplier(TDM)Current ( I / I pickup )1.5 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0IAC Extremely Inverse0.5 1.699 0.749 0.303 0.178 0.123 0.093 0.074 0.062 0.053 0.0461.0 3.398 1.498 0.606 0.356 0.246 0.186 0.149 0.124 0.106 0.0932.0 6.796 2.997 1.212 0.711 0.491 0.372 0.298 0.248 0.212 0.1854.0 13.591 5.993 2.423 1.422 0.983 0.744 0.595 0.495 0.424 0.3706.0 20.387 8.990 3.635 2.133 1.474 1.115 0.893 0.743 0.636 0.5568.0 27.183 11.987 4.846 2.844 1.966 1.487 1.191 0.991 0.848 0.74110.0 33.979 14.983 6.058 3.555 2.457 1.859 1.488 1.239 1.060 0.926IAC Very Inverse0.5 1.451 0.656 0.269 0.172 0.133 0.113 0.101 0.093 0.087 0.0831.0 2.901 1.312 0.537 0.343 0.266 0.227 0.202 0.186 0.174 0.1652.0 5.802 2.624 1.075 0.687 0.533 0.453 0.405 0.372 0.349 0.3314.0 11.605 5.248 2.150 1.374 1.065 0.906 0.810 0.745 0.698 0.6626.0 17.407 7.872 3.225 2.061 1.598 1.359 1.215 1.117 1.046 0.9928.0 23.209 10.497 4.299 2.747 2.131 1.813 1.620 1.490 1.395 1.32310.0 29.012 13.121 5.374 3.434 2.663 2.266 2.025 1.862 1.744 1.654IAC Inverse0.5 0.578 0.375 0.266 0.221 0.196 0.180 0.168 0.160 0.154 0.1481.0 1.155 0.749 0.532 0.443 0.392 0.360 0.337 0.320 0.307 0.297Multiplier(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
