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> SNIP
> >
> > I am curious what PTCs you are
using. I used PTCs
> > on some circuits. I used
> > a
Buss ATC form breaker, removed the bimetallic and
> > soldered a PTC to
the
> > frame. Then plugged into a ATC fuseblock.
This
> > worked well, bit I am
> > curious if you found a
packaged PTC.
> >
> > Thanks,
> > Joe
> >
Concerning the PTC devices, I was interested in them and
a friend also building a Cozy wants to use the PTC devices but I am reluctant to
say to use them. If correct, many of the ones Mouser lists that allow high
current (1 - 18 amp) seem to have an awfully high holding current; that is, the
current to maintain the device temp to hold it in the tripped state. Be
careful of the device you choose, it's holding current could be 50% of the trip
value (Littel 30R series for instance). This would not be good for
protecting the wiring.
Also, you need to know the max interrupt current.
A battery can dump a lot of current through a fuse before it goes and it must be
able to interrupt that current. A typical 5 amp fuse can flow over 75
amp in a battery supply situation before it blows. Some fuses might actually
weld together and never interrupt the current when used in a
battery powered situation. I had to do some UL testing on some fuses
many years ago and it would surprise you how much current a small fuse
will pass before blowing. Will your wire take the current that a direct
short can deliver, of course different for each situation, something to think
about even when using breakers. This is why they need to rated
for battery supply use.
Wendell
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