In a message dated 1/19/2006 7:46:52 A.M. US Mountain Standard Time,  

I just  won a GSA auction for a 400 Hz/60 Hz 25kVA motor
>generator set.   I'm not sure whether it eats 400 Hz or
>60 Hz.  Regardless, in a  perfect world I can hook a diesel
>to the end shaft and spin it.   In a really perfect world,
>both the 400 Hz and 60 Hz machines are  synchronous, and
>both can be generators.  400 Hz will drive  resistive loads
>(like my furnace elements) just  fine.

Nearly all applications take 60Hz power and turn the 400Hz generator, the  
output of which is very easy to convert to a ripple free DC power.  You are  
correct that 400Hz will run resistive loads quite well.  Power cables  carrying 
400Hz had to be oversized as the current flows primarily on  the surface of the 
conductors.  Mg sets also used inertia to carry  them through small power 
transients, such as switching from shore power to  onboard power.  Ride through 
was typically 30cycles, or about 1/2 a  second.  
Typical applications would be big computers, radar, and communications  gear, 
all of which don't like being turned off.  All have big DC power  supplies.  
I recall IBM and Hitachi mainframes having as many as 5 MG sets  built into 
them during the 90's,    Your  2000 # plus  MG sounds a bit heavy for an 
aircraft, but that is out of my field of  endeavor.
Now, main frames fit in a desk space, run off two 30amp, 60  Hz, services, 
and MG sets ( and old mainframes for that matter) can be had  for the cost of 
toting them away.  I recall one buyer, who paid $1  for each mainframe, shipped 
them to China to have them stripped  for all the various metals.
Thanks for the memories,  

Jim  Friesen
Phoenix AZ
79 300SD, 262 K miles 
98 ML 320, 140 K  miles

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