When the original Niagara Falls power station was in its planning stages, the planners were uncertain on how they would distribute power, and were considering u

When the original Niagara Falls power station was in its planning stages, the planners were uncertain on how they would distribute power, and were considering using compressed air before they decided to generate electricity instead. Unfortunately, they specified turbines that operated at 250 RPM, making it impractical to directly produce 60 Hz AC, or 30 Hz for that matter, which would have made frequency converters relatively cheap. Instead, 25 Hz became a North American standard for industrial power, and a few legacy customers remained as late as 2006. [0] Much of Amtrak's Northeast Corridor, and SEPTA's rail network in the Philadelphia area, still use 25 Hz for traction power, provided from converters or from a few hydroelectric plants that have 25 Hz generators. [0] https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4412948 https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4412948