Wed Sep 03, 2014 9:46 am
They were military compressors used in aircraft and other vehicles that had 24 volt, 400 cycle electrical systems. Frequencies as high as 400 Hz are used in aircraft, spacecraft, submarines, server rooms for computer power, military equipment, and hand-held machine tools. Such high frequencies cannot be economically transmitted long distances, so 400 Hz power systems are usually confined to a building or vehicle. Transformers and motors for 400 Hz are much smaller and lighter than at 50 or 60 Hz, which is an advantage in aircraft and ships. A United States military standard MIL-STD-704 exists for aircraft use of 400 Hz power.
The were common as surplus and modified to fill scuba tanks. Yours appears to be two compressors tied together. Most were modified to run on normal 110 volt 60 cycle power or a gas engine.
Captain