RK05 spindle pulleys - trade 50Hz vs 60Hz?

[Paul Koning]

> On Jul 26, 2018, at 9:55 AM, W2HX via cctalk <cctalk at classiccmp.org> wrote:
> 
> That is not the whole story of 400Hz. The other part of that story is that now, all of the downstream equipment that uses the 400 Hz can have much simpler AC to DC power supplies in them. At 400 Hz it is much easier to regulate and filter out ripple. So instead of every piece of equipment each having lots of large capacitors, now they only need small capacitors. Space is at a premium as well as weight on a plane. 

This even applies to some terrestrial equipment.  CDC used 400 Hz 3-phase power for the 6000 series mainframes.  3-phase power cuts the ripple by a large fraction and raises the ripple frequency 3x; 400 Hz instead of 60 or 50 raises the ripple frequency further by that ratio.  So high power supplies get much smaller, both in the transformers and in the filter capacitors.

The 400 Hz came from motor-generators.  Those also clean up the power a lot, because any spikes or brief dips are absorbed by the mechanical intertia and don't appear on the output.

	paul