Multi-ton transformers damaged by such a storm might take years to repair.
This effect has been observed on a small scale (nasa.gov):
A similar flare on March 13, 1989, provoked geomagnetic storms that disrupted electric power transmission from the Hydro Québec generating station in Canada, blacking out most of the province and plunging 6 million people into darkness for 9 hours; aurora-induced power surges even melted power transformers in New Jersey.
Another Carrington-class flare would dwarf these events.
The Department of Homeland Security issued a risk assessment in 2011 that said (p. 3):
Recent estimates state that 300 large extra-high-voltage transformers in the United States would be vulnerable to geomagnetically induced currents. Damage to an extra-high-voltage transformer from geomagnetically induced currents could take months or even a year to repair and cost in excess of $10 million.