Geomagnetically Induced Currents (GICs) enter the Bulk Power System primarily through which type of equipment?

Geomagnetically Induced Currents (GICs) predominantly enter the Bulk Power System through grounded equipment. During geomagnetic storms, fluctuations in the Earth's magnetic field can induce electric currents in conductive materials. Grounded equipment, such as transformers and transmission lines, provides a pathway for these induced currents to enter the power system.

When grounding occurs, it connects the electrical system to the Earth, creating a route for the GICs to follow. This can result in various operational issues, including voltage instability and damaging heating effects within power system components.

The other options involve equipment that either does not provide a direct path for GICs or is less likely to facilitate their entry into the power system. For example, isolated transformers do not have a direct connection to the ground, reducing their susceptibility to GICs. Ungrounded conductors are designed to avoid unintentional paths for fault currents and would also be less affected. Self-regulated generators may have mechanisms in place that regulate their output, but they do not primarily serve as entry points for GICs into the grid. Thus, understanding the role of grounded equipment as the primary entry point of GICs helps enhance the management and mitigation strategies during geomagnetic events.