ERLANGEN, Germany (Reuters) -Siemens Energy is expecting to start U.S. production of big industrial power transformers in 2027 and can further expand its Charlotte factory if demand, and import tariffs, stay high, senior executives at the group said.

Siemens Energy makes more than a fifth of its sales in the U.S. market, where it employs around 12% of its roughly 100,000 staff and runs several production plants that make everything from wind and gas turbines to electricity grid components.

Overall, more than 80% of so-called large power transformers (LPT) - bus-sized components needed to convert voltage levels for grid transmission - are currently imported into the United States, Siemens Energy board member Tim Holt said.

That's why Siemens Energy is expanding its site in Charlotte, North Carolina, where the first local LPTs are expected to run off the factory lines in early 2027, Holt said, adding there was enough space to expand further if needed.

The company expects a total of $2 trillion of investment in the dated U.S. power grid by 2050, fuelled by an expected surge in power demand thanks to data centres that are needed for artificial intelligence technology.

"This time we expect a longer boom cycle for grid expansion than the usual two to three years. The market is very positive right now," Holt, who is in charge of Siemens Energy's U.S. business, said at a company event.

Siemens Energy's finance chief Maria Ferraro said the group was taking a mid- to long-term view on the U.S. market, at a time when some firms are reconsidering their footprint there in the wake of U.S. President Donald Trump's trade war.

"Do we change our tactic or the way to approach the U.S.? I would say no, because we already have a long-established basis there and it is a key market for us," Ferraro said.

Siemens Energy said in May it expected U.S. import tariffs to cut less than 100 million euros ($117 million) from group net profit in 2025, comments that were made before Trump threatened 50% levies on EU goods if a deal cannot be agreed by July 9.

"Any large change in the tariffs would also mean a review of our estimated impact," Ferraro said.

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