This is considering the effect of electric current on the human body,
most specifically, fibrillation of the heart. See IEC 479-1. For long
durations (with respect to the human heart rhythm) fibrillation depends
on current, around 50 mA. For durations shorter than a heart beat it
takes on the order of 1 A. For short impulses, the heart's response is
basically proportional to the integral of I(t), in other words, the
total charge transferred. For very short impulses factors other than
fibrillation, such as burning/charring occur before fibrillation, so an
energy limit is imposed.
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Jon Bertrand said:
. . . Does anyone know why there is a charge limit on hazardous
voltages (up
to 15kV) and not an energy limit? (I'm referring to EN61010-1 but
I'd
guess it's the same in EN60950).
Charge seems like a strange thing to limit. I would think you would
want to limit energy.
Can't you do more "work" with 45uC at 14.9kV ( = 4995 Joules) then
you
can with 45 uC at 100 V ( = 0.225 Joules)? More work means more
burns, more fire, more harm. And why 45uC?
