[David]

In the 19 century you could find AC an DC power. The last of the Edison DC system went away in New York City around 1980? The US power grid inter connect got under way after WWII. Before you would find 25Htz, 30Htz, 40Htz, 50Htz, an 60Htz. Many small towns would run the generator at a slower speed so as to save wear an tear on the system. In South America better take a volt meter. In Japan the islands in the south are 50Htz at 100 volts. If you take a 2 pole generator running at 3600 rpm you get 120 volts AC at 60Htz. Slow it down to 3000rpm you get 100 volts at 50Htz. So at the end of WWII the islands were using US military stuff to make power. So some electricity is better than none.