Protective Relay Settings: relay_setting
Protective relay settings and coordination parameters per IEEE C37 and IEEE 242. Covers IEEE C37.112-2018 inverse time-overcurrent curve constants (A, B, p, tr) for moderately/very/extremely inverse curves and SEL vendor extensions; IEC 60255-151 curve constants (k, alpha); CT accuracy classes C100/C200/C400/C800 per IEEE C57.13-2016 with burden limits; relay pickup guidance by ANSI device number (50, 51, 50N, 51N, 27, 59, 81U, 81O); coordination time intervals (CTI) per IEEE 242-2001; and CT saturation voltage thresholds.
| parameter type | record id | curve designation | curve name | curve standard | notes |
|---|---|---|---|---|---|
| relay_setting | ct_ratio_selection | CT_RATIO | CT Ratio Selection Guidance | IEEE C57.13 | CT ratio = max load current / rated secondary; typical secondary 5A; standard primary ratings: 50 100 200 400 600 800 1200 1500 2000 to 5A |
| relay_setting | ct_saturation_check | CT_SAT_CHECK | CT Saturation Voltage Check | IEEE C57.13 | Check: Vs >= If_sec*(R_lead + R_relay); Vs=knee-point voltage; If_sec=max fault current on secondary; prevents CT saturation |
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