**4. Non-Unit Protection Scheme Challenges**

In the previous section it was shown that faults can be cleared within 1 μs by utilizing overcurrent and current rate-of-change detection in combination with an SSCB. Fast and robust fault interruption is possible with such an approach, since no communication infrastructure is utilized. However, in this section it will be shown that achieving selectivity can be challenging when using these non-unit protection methods.
