Auto Power Environment

[Eric Bryant]

> From: ae2598 at wayne.edu [mailto:ae2598 at wayne.edu]
> Subject: Re: Auto Power Environment
> 
> 
> I've heard that 42VDC systems are going to happen pretty 
> soon, to reduce
> the current and thus, the size of the conductors.  What I'm wondering
> though, is where they came up with the number 42? (Yes I 
> know, it is the
> meaning of life :)  but other than that, is 42VDC used 
> anywhere?  24VDC is
> a "magic number", it is the standard voltage for industrial control
> systems.  I've heard that utility substations use 100VDC for 
> some reason.
> but 42V?!

42 V won't appear overnight.  You're looking at about 2010 for 10% market
penetration, by current estimates.  

I think that 42 V works well because it's a large-enough jump over 12 V to
make a worthwhile difference, but yet it's not so large as to cause a shock
hazard.  I'm not familar enough with various regulatory standards on what
voltages are considered to be "safe", but I know this played a role in the
decision.  I'm sure there's some many, many other issues that played a role
in this decision, such as power semiconductor voltage ratings vs. cost,
battery size, and so on.

Or, hell, maybe they pulled that number out of a hat:)


Eric Bryant
mailto:bryante at ghsp.com
http://www.novagate.com/~bryante  
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