[Elecraft] K3: Power cable question

[Brian Lloyd]

On Jun 16, 2008, at 9:59 PM, <d.cutter at ntlworld.com> <d.cutter at ntlworld.com 
 > wrote:

> A regular fuse should blow at 2.6 x the rating within 30s, in other  
> words very slowly.  It's only a short circuit that will normally  
> blow a new fuse.  Have not seen any data on old fuses which might  
> get metal fatigue.  There are faster fuses, but the fastest are rf  
> transistors - on three legs anyway...

Most people don't know that the purpose of a fuse or circuit breaker  
is to protect the power distribution wiring, not the electronic  
component itself. Wire will carry a surge without too much temperature  
rise. The idea is that the fuse will blow or the breaker open before  
there is any chance of damage to the wire.

This means that a fuse or breaker cannot protect your active devices.  
If you want that level of protection you need something like a power  
supply with fold-back current limiting.

Brian Lloyd
Granite Bay Montessori School          9330 Sierra College Bl
brian AT gbmontessori DOT com          Roseville, CA 95661
+1.916.367.2131 (voice)                +1.791.912.8170 (fax)

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