Stupid question of the day....

I suggest that you figure out who your nemisis is! He will bury your slimey ass in anything technical! ..which isn't all that hard, really.

On Sun, 07 Aug 2005 18:59:43 -0500, John Fields Gave us:

Same question you refused to answer last time. When was the last time you used a soldering iron?

Neither. But if you fill a typical plastic garbage can with boiling water, expect to be knee-deep in it pretty soon. Trust me on this one.

John

What you 'believe' you said, and what is in the archive are two different things. Deal with it.

daestrom

But you DO have to admire consistency like that...

Bob M.

No silly. What I'm talking about is not a phase change from solid to liquid (soldering and welding are examples of that).

Steel and many other alloys undergo 'phase changes' from one form of solid to another form of solid. The crystaline structure shifts from one form to another *without* becoming a liquid. Looking at a bar of low-carbon steel in a furnace before/after such phase changes, you cannot see any difference. Sudden cooling back down below the transition temperature ('quenching') can trap the crystaline structure in the high-temperature state, providing useful properties (look up 'hardening'). Alternatively, it may be heated well above the transition, then cooled very slowly to remove brittleness ('annealing').

Materials like this have very marked changes in thermal conductivity at these transition temperatures and often absorb/liberate a fair amount of heat with no significant temperature change while this crystaline change occurs.

daestrom

On Mon, 08 Aug 2005 15:58:06 -0500, John Fields Gave us:

I doubt it.

On Mon, 08 Aug 2005 23:07:43 GMT, "daestrom" Gave us:

You're an idiot. You got shown to be way off. You deal with it.

On Mon, 08 Aug 2005 23:19:08 GMT, "daestrom" Gave us:

I wasn't talking about that. I was talking about the differences in the way the heat that is generated in each of those systems travels in the mediums local to the work being done.

In soldering, only surface interfaces are typically made The items being joined do not meld into the joints themselves, and the heat is local to the joining but soaked in the nearby local medium before and during the solder joint making. The joining media is usually different than the mediums joined.

In welding, the surfaces being joined are actually melted and considerable additional like material is introduced. The finished joint consists of parts of both joined mediums and the added media becoming part of the joint at depths that are near half the thickness of the joined parts.

The types of heat transfers that were being discussed closely reflect the way welded steel works. Silly.

On Mon, 08 Aug 2005 23:19:08 GMT, "daestrom" Gave us:

I don't need to look up hardening.

I used to build chillers. That goes beyond hardening.

Look it up.

But it does!

At 60 Hz, the "skin effect" caused most of the current to flow within 1/2" of the surface. That's why conductors over 1" or so either have steel for strength or might have a light weight filler since a solid conduction would add to the weight but not to the electrical performance.

Beyond a certain current capacity, it makes sense to have several conductors that aer a little over 1" in diameter than a single conductor that is sized as needed. There are likely other considerations too: the separate conductors would have more area and would be more effectively cooled by the air in the line is really being pushed.

On Tue, 9 Aug 2005 08:54:56 -0400, "John Gilmer" Gave us:

Multiple segregated conductors is how Litz wire works. The effective surface area or "skin" if you will, is greater. On low frequency, high tension lines, it is handled by four or five physically separated larger than 1" diameter lines. They may or may not be electrically segregated along their length.

In a high frequency switcher transformer, it is multiple strands of mag wire separated by their enamel, and connected only on their ends. The Litz bundle can carry more current than a solid wire in such cases as it will drop less voltage at higher frequencies.

Both cases yields more cross sectional area for conduction through the line.

Either an Electrolux or a Hoover.

;-)

Hey, My Dirt Devil, 2C

The house clean before it ever gets dirty....

;^)