What is the impact of improper grounding on the accuracy of differential protection schemes in a substation?

Differential protection is a protection scheme used to detect internal faults within a defined zone, such as a transformer or a busbar. It operates by comparing the current entering and leaving the protected zone. Under normal operating conditions or external faults, the current entering should equal the current leaving (after accounting for any transformer turns ratios or phase shifts). If there's an internal fault, the currents will be significantly different, causing the differential relay to trip. Proper gr....