Well said Pete, I failed to mention -
The Belden tables assume complete 360 degrees of air around the cable for radiation and convection and at an ambient 25C. And as usual, the particular use within a system cannot be calculated by an equation. Tables should be used as a guide. Doug At 02:34 PM 11/3/98 EST, Pete Van Raalte wrote: >Doug, > >I agree that Belden's catalogue is an excellent guide. However, you >should be aware that it is conservative. When I called Belden, they >said they have to be conservative because they don't know the boundary conditions. > >Heat is removed from wire by convection and radiation along the length. >and by conduction through the end terminations. >Since Belden's tables provide advice on various >conditions of convection, all kinds of termination, and a variety >of lengths, their numbers are not exact. > >My experience is that it is much more practical to "build one and >measure it" than to rely on simple equations. Only the military can >afford full-bore computerized thermal modelling, and that's not quick >or easy. > >Pete
