Austrian Standard traction voltage is 15kV 16 2/3 Hz. Actually I don't know the voltage of the lighting system, but it's 16 2/3 Hz.
Vienna subway and streetcar (tramway) cars run on various voltages DC. Standard streetcar is 650V DC nominal. The oldest cars ran 120V light bulbs with ES27 screw threads in series, then fluorescent tubes and light bulbs in series (I think 220V fluoros and 120V bulbs, later converted to 220V bulbs). Rotary inverters existed too, but mostly for converting the 600V DC to 24V DC for the controls like door control, trailer emergency brake,...
From the late 1970ies on cars had solid state inverters to power 220V fluorescent lighting.
The old metropolitan railway of vienna ran on 750V DC and the cars had 95V bulbs wired in series. Directly replaced with solid state inverter cars (the cars were built in 1925, rebuilt using some parts of the old cars, like most of the electric part in 1954-1961 and taken out of service in 1983). New cars were bought from 1980-89 and are still in service.
