From the Introduction: "Over the past several weeks, the Trump Administration has taken actions to limit the use of foreign manufactured products in the U.S. power grid. On May 1, 2020, the President declared a national emergency (E.O. 13920) invoking the International Emergency Economic Powers Act (IEEPA) to prohibit certain international transactions for bulk-power system electric equipment used to operate the national grid. On May 4, Secretary of Commerce Wilbur Ross, announced a new investigation under Section 232 of the Trade Expansion Act of 1962 into whether imports of certain large electrical transformers and their parts threaten national security. These actions may suggest a pattern, begun last year, of making use of executive national security authorities to restrict imports of goods that may be used for critical infrastructure (e.g., telecommunications and electrical equipment)."
CRS Insight, IN11401
Congressional Research Service: https://crsreports.congress.gov/