Hence the reason for 3AC fuses. They have a ceramic body and don't explode. Of course the only way to tell if they are open is to measure them.
Bob, K4TAX Sent from my iPhone > On Jul 15, 2018, at 10:18 AM, K9MA <[email protected]> wrote: > > Also, fuses rated 250 V AC are typically rated only 32 V DC. That's because, > with AC, the current goes to zero twice per cycle, so the arc can go out. Not > so with DC. I suspect the standard 28 V DC once used in many aircraft was > chosen because that's about the highest voltage which can be switched with a > mechanical relay or switch. (Something about the energy required to strip > electrons from the metal contacts.) Solid-state switches, of course, don't > have that problem, hence the popularity of higher voltage DC systems now. > > Long ago, I put a 3AG fuse in series with the finals' cathodes of a T-4XB. > The first step in replacing that fuse when it blew was to shake all the glass > out of the radio. > > 73, > Scott K9MA > > > >> On 7/15/2018 05:22, Roy Koeppe wrote: >> One reason 'all fuses' aren't just rated at 250v to be done with it is that >> a shorter element section in a lower voltage fuse can have a lower >> resistance, due to the shorter arc gap allowed. Thus lower voltage drop for >> a low voltage circuit, etc. >> >> 73, Roy K6XK >> >> >> >> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] > > > -- > Scott K9MA > > [email protected] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
