Re: Tesla the man

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 08:44 PM 4/25/2007, you wrote:
> Original poster: FIFTYGUY@xxxxxxx
> In a message dated 4/25/07 8:34:44 P.M. Eastern Daylight Time, 
> tesla@xxxxxxxxxx writes:
> >and the
> >International Space Station, which uses 120V DC power everywhere.
>
>     Why?

spacecraft have generally used DC buses, historically 24VDC. But, 
higher bus voltages save a lot in IR losses, not only in the wiring 
harness (every gram counts in space.. costs a year's pay to get a 
kilo into orbit) but in the DC/DC power converter primaries.  So you 
want to go as high as you can without starting to get into two problems:
a) voltage ratings on the semiconductor devices (sound familiar to 
you SSTCers?).. you want some serious margin so the device doesn't 
fail on a transient and/or a charged particle event
b) corona or spark over.

Typically in space flight, we test at twice the rated voltage.

The solar panels on the station run at around 140VDC and it's 
converted to 120V for distribution, and then converted down to 5, 
3.3, 24, or whatever inside the box.


> -Phil LaBudde
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