CHAPTER 5: SETTINGS GROUPED ELEMENTSL90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 5-2375A, B, p = constants defined in the tableTRESET = reset time in seconds (assuming energy capacity is 100% and RESET is “Timed”)tr = characteristic constant defined in the tableTable 5-28: IEEE inverse time curve constantsTable 5-29: IEEE curve trip times (in seconds)IEC curvesFor European applications, the relay offers three standard curves defined in IEC 255-4 and British standard BS142. Theseare defined as IEC Curve A, IEC Curve B, and IEC Curve C. The IEC curves are derived by the operate and reset timeequations.Eq. 5-16whereIEEE curve shape A B p t rIEEE Extremely Inverse 28.2 0.1217 2.0000 29.1IEEE Very Inverse 19.61 0.491 2.0000 21.6IEEE Moderately Inverse 0.0515 0.1140 0.02000 4.85Multiplier(TDM)Current ( I / I pickup)1.5 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0IEEE Extremely Inverse0.5 11.341 4.761 1.823 1.001 0.648 0.464 0.355 0.285 0.237 0.2031.0 22.682 9.522 3.647 2.002 1.297 0.927 0.709 0.569 0.474 0.4072.0 45.363 19.043 7.293 4.003 2.593 1.855 1.418 1.139 0.948 0.8134.0 90.727 38.087 14.587 8.007 5.187 3.710 2.837 2.277 1.897 1.6266.0 136.090 57.130 21.880 12.010 7.780 5.564 4.255 3.416 2.845 2.4398.0 181.454 76.174 29.174 16.014 10.374 7.419 5.674 4.555 3.794 3.25210.0 226.817 95.217 36.467 20.017 12.967 9.274 7.092 5.693 4.742 4.065IEEE Very Inverse0.5 8.090 3.514 1.471 0.899 0.654 0.526 0.450 0.401 0.368 0.3451.0 16.179 7.028 2.942 1.798 1.308 1.051 0.900 0.802 0.736 0.6892.0 32.358 14.055 5.885 3.597 2.616 2.103 1.799 1.605 1.472 1.3784.0 64.716 28.111 11.769 7.193 5.232 4.205 3.598 3.209 2.945 2.7566.0 97.074 42.166 17.654 10.790 7.849 6.308 5.397 4.814 4.417 4.1348.0 129.432 56.221 23.538 14.387 10.465 8.410 7.196 6.418 5.889 5.51310.0 161.790 70.277 29.423 17.983 13.081 10.513 8.995 8.023 7.361 6.891IEEE Moderately Inverse0.5 3.220 1.902 1.216 0.973 0.844 0.763 0.706 0.663 0.630 0.6031.0 6.439 3.803 2.432 1.946 1.688 1.526 1.412 1.327 1.260 1.2072.0 12.878 7.606 4.864 3.892 3.377 3.051 2.823 2.653 2.521 2.4144.0 25.756 15.213 9.729 7.783 6.753 6.102 5.647 5.307 5.041 4.8276.0 38.634 22.819 14.593 11.675 10.130 9.153 8.470 7.960 7.562 7.2418.0 51.512 30.426 19.458 15.567 13.507 12.204 11.294 10.614 10.083 9.65410.0 64.390 38.032 24.322 19.458 16.883 15.255 14.117 13.267 12.604 12.068
