Rotary Converter, IRT Subway, Substation 13, Midtown Manhattan, NYC, 2017.'nAll the pixels, no hearing protection required, at https://www.flickr.com/photos/mattblaze/32992380451'n#photography

[mattblaze@federate.social]

Rotary Converter, IRT Subway, Substation 13, Midtown Manhattan, NYC, 2017.

All the pixels, no hearing protection required, at https://www.flickr.com/photos/mattblaze/32992380451

#photography

[mattblaze@federate.social]

NYC's IRT subway, opened in 1904, is powered by a 600 volt DC third rail running alongside the tracks. Power is fed to the system via a number of substations throughout the city, where high voltage AC is converted to the lower voltage DC used by trains.

Until recently, this was done with electromechanical rotary converters (essentially a combination AC motor and DC generator). They are now supplanted by solid state rectifiers, but a few of the original rotary converters remain operational.