In Richard wrote:
Frank wrote:

That is to get Smaller Transformers, war time planes use 80hz, and
IBM main frame computers I think from memory used 400hz

Why on earth would a mainframe need 400Hz? Thats just silly talk roger

But he's correct. Mainframes did often use 400 hertz power supplies. All
those power supplies and large motors for fans and disk drives used so
much power that it was worth using a motor-generator set to convert the
normal three phase 50 or 60Hz power supply to 400Hz. The extra cost and
loses in the motor-generator were more than offset by the increased
efficiencies and smaller size and costs of all the other transformers
and motors in the mainframe.

--
Roger Johnstone, Invercargill, New Zealand
http://vintageware.orcon.net.nz/
__________________________________________________ ______________________
No Silicon Heaven? Preposterous! Where would all the calculators go?

Kryten, from the Red Dwarf episode "The Last Day"