28V semantics
28V semantics
(OP)
I am wondering why in the automotive world cars, with 12V batteries, are deemed 12V systems even though they are 13.2V to 14.7V typically but in the aviation world they call planes 28V even though they have 24V batteries and pushed in the charging realm may reach ~27V?
Keith Cress
kcress - http://www.flaminsystems.com





RE: 28V semantics
TTFN
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RE: 28V semantics
Keith Cress
kcress - http://www.flaminsystems.com
RE: 28V semantics
However, most aircraft rarely run on batteries for extended periods, and the power converters have to be sized for the alternator outputs, which, for MIL-STD-704 are quite ragged. Additionally, the overall voltage range of both mil specs cover 24V, since the standard voltage range is 22V to 29V.
Most airliners run on on-aircraft auxiliary power units (APUs) while on the ground, or directly off ground-based APUs.
On many aircraft, the batteries don't even go to all the electrical systems, thus making it imperative that they can reliably run on 28V from the APU as opposed to battery that might not even be there.
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: 28V semantics
RE: 28V semantics
Thanks gentlemen.
Keith Cress
kcress - http://www.flaminsystems.com
RE: 28V semantics