Think of Fault Current Limiters (FCLs) as advanced and large-scale surge protectors capable of protecting large portions of the electric power grid. Any homeowner knows that surge protectors limit the damaging currents that can harm plugged-in household devices. Simply put, FCLs can provide that same service for electric utilities. These specially designed devices allow for uninterrupted electrical service by limiting and regulating the amount of current moving through the transmission and distribution systems under abnormal conditions.

The emerging technology of FCLs has the potential to save money for utilities and increase efficiency for their customers by protecting equipment from damage and avoiding interruptions and outages. As the demand and sources for electricity rise, utilities are grappling with the challenge of more frequent and larger "fault currents."

Blackouts cost the U.S. economy somewhere between $104 billion and $164 billion annually, according to figures from the Electric Power Research Institute. EPRI's research, conducted in 2001, was compiled by the Consortium for Electric Infrastructure to Support a Digital Society (CEIDS) (PDF 581 KB). Utilities fear outages caused by fault currents could become more common as the demand for electricity continues to grow, especially in urban centers. The risk of larger fault currents also grows as more and more power sources are fed into the grid.

For instance, almost half of the states have mandates requiring the grid to handle significant boosts in the amount of energy from renewable sources such as solar and wind. These renewable energy sources are often connected in large numbers at specific locations in the electrical grid and can produce fault currents in excess of local limits.

Interest in advancing the use of FCLs is growing as utilities and the Department of Energy collaborate with manufacturers, national laboratories, and other stakeholders to modernize, expand and increase the capabilities of the nation's stretched-to-capacity electric grid. FCLs have the potential to play a pivotal role in transforming the current grid into the DOE's vision for a smart and more efficient grid.

During a ground fault, an FCL safely mitigates excess energy and prevents damage by switching to a high impedance state, which would normally affect utility transmission and distribution equipment.

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