[Amps] HV Fuses

Ron Youvan ka4inm at tampabay.rr.com
Wed Feb 17 06:07:03 PST 2010


> In the old car ignitions there was a capacitor in parallel between the 
> points. This was made to avoid an arc between the points when the point 
> were switching off 12 Volts into the coil primary.

> What we are trying to avoid in an hV fuse is also an arc when the 
> circuit breaks (when the fuse melts).

> So how about using an HV capacitor in parallel with the fuse? would that 
> keep an arc from appearing?

> Anyone tried this?

   The reason and result are different.  In Kettering ignition systems
the capacitor was to resonate the coil at a lower frequency which
produced a lower frequency sine wave spark Voltage, producing a
first half wave that lasts longer than it would have if naturally
tuned.  It did prevent arcing at the "points" as a side effect.
A capacitor across a fuse would carry a brief spike of current
which would not be helpful.
-- 
    Ron  KA4INM - I'm proud to be Chuck's pop!


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