Re: (ET) Ok, 400a fuse it is...

["David Roden" <etpost drmm net>]

Fuse selection isn't always as trivial as it looks.  For example, fuses 
have 
a time delay.  That's one reason that sometimes you find a smaller fuse 
than 
you'd expect in a particular circuit.

You can get the details from your fuse's spec sheet, but to pull some 
numbers out of thin air, a given fuse might open after 1 hour at 90% of 
its 
rated current, 20 minutes at 100%, 10 minutest at 120%, 5 minutes at 150%, 
and 1 second at 1000%.  (Again, these are made up numbers, check the 
datasheet.)  

Another thing to consider: what's the total resistance of all the ET 
wiring? 
Sometimes the wiring in an appliance or EV is deliberately undersized, so 
it 
can act as a cheap and dirty current limiter.  Is the ET wiring resistance 
high enough that a dead short at the motor might not blow a 400 amp fuse 
before bad things happen?  I don't know, I've never measured it, I'm just 
wondering.


David Roden - Akron, Ohio, USA

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