DC Transmission Re: primary solid/tube

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>


> I was fascinated to find out that DC!! Is used in long distance power 
> transmission!

	In _some_.  In a minority of cases.

> Wow I thought one could not transmit DC more than a few miles. 

	This gets oversimplified in most explanations in texts.
	DC (as such) can be sent any distance.
	DC (in Edison's time) could not be run up and
	down in voltage easily.
	  low voltage (of either sort) does NOT travel well:
	  large powers require high currents, leading to
	  high losses.
	   AC (by use of transformers) Allows easy, efficient,
	   change of voltage:  high for 'transmission', low
	   for distribution/use.

> And that this why we all use Tesla's AC and not Edison's DC.

	Edison was limited by the technology of the time:
		commutators and generators good to maybe
		600V max.
	AC, via transformers, could easily go to 1000s of
	volts, and had no commutator to worry about.
	(in many cases....)

	Historically: post Edison, some 'interesting'
	attempts at DC HV systems were made, but did not
	work out until just before (or after???) WWII, when
	thyratrons allowed rectifying and chopping the DC
	back to AC.  DC links got MUCH more popular when
	solid state devices got to handle signifucant power.

	best
	dwp

...the net of a million lies...
	Vernor Vinge
There are Many Web Sites which Say Many Things.
	-me