As inverter-based resources become more common, we need to reconsider some of the assumptions that underpin our traditional approach to power system protection and control. SEL power system engineer Ellery Blood details how inverter-based resources behave differently from traditional power generation sources and how these differences affect protection system reliability. The presentation concludes with a case study from a Brazilian solar farm that illustrates how inverters and their built-in protection algorithms can complicate fault detection and location.