Amazing and very interesting. It seems for every accepted modern technology there were always alternative ways used in the past which have been almost forgotten. Take the crank pin and crankshaft, back in the early days of steam power, someone had a patent on that, so someone else thought up two cog wheels rotating round each other in a similar motion with tie rods to keep them in mesh but did not transmit power. Or take the poppet valve used in engines, an american, Mr Knight invented a sleeve valve sold under the name Silent Knight, which fitted between each piston and cylinder in an engine, which allowed much larger inlet and outlet ports to be in the wall of the cylinder. In the calculation field, there have even been base 3 mechanical calculators using digits 0, +1 and -1 instead of conventional binary or BCD. I would think the slip rings would produce the odd spark which would generate big glitches. Looking on Wikipeda, it says 'Rotary Converter' covers both types, and they say, even covers motor generator sets. Nor me, thats why I bought the proper diesel powered generator, though almost antique and a hundred times bigger than a modern generator, it would just chug on continuously, for years on end if I needed it to with simple topping up of oil, water and fuel and a twist of the oil cleaning discs now and again. One decade I might have to give it an oil change I suppose, its probably got some of the original wartime oil in it, incredibly diluted of course with all the new stuff added over the years. The other maintenance was to periodically wash the exhaust through with caustic soda (sodium hydoxide) to unblock all the carbon deposits.