being as I am so dumb - can someone explain this to me?

[dedndave]

yah - they are too busy spending money on an unneeded underpass in Boston
but, hey, at least the rich-ass contractors that paid off the politicians are making out

personally, i think a larger number of smaller generators would be a good start
we need to be using solar and geo-thermal energy
wind and other sources are nice, too - but solar and geo-thermal have an added advantage
they help to reduce the global temperature   :U

[xanatose]

Tesla wanted to make energy avaiable to everyone. He foresaw the problem with nonrenewable energy sources and out of control energy waste. The idea was to use the earth natural forces (hydro-electrical, thermo-electrical) and be able to send it huge distances by resonating the magnetic field of the earth. Problem is that the instalations need to be huge in order to cause the resonance effect on the earth magnetic field.

http://www.reformation.org/tesla-wireless-transmission.html
http://www.teslauniverse.com/nikola-tesla-patents-1,119,732-transmitting-electrical-energy

We are talking about a guy that was not only the father of modern technology, but also the creator of an earthquake machine based on resonance. He new first hand on the power of resonance. If you send the energy at the correct frequency, you could get the magnetic field to resonance, thus the energy send would increase (just like a sound wave that makes a material resonate).

[anunitu]

I watched a history channel show on Tesla..He was the one that came up with AC current,is responsable for the electric moter among other things we take for granted. Edsion wanted only DC for power, and Edison "Stole" an invention from Tesla(Tesla worked for Edison,and was promised a large sum for inventing something for Edison) Edison screwed tesla for the money. Gives a different perspective about Edison. If you get a chance to view the History channel's show on Tesla, watch it. Tesla was a bit strange, and said he was in communacation with Alians. Tesla was WAY ahead of his time.

[dedndave]

i am an engineer - you think i'd idolize Edison, right ?
nahhhhhh
he was an asshole thief - lol
more of a patent attorney than an inventor
to date, he still has more patents than anyone in history
but - that is because he was an expert at getting his name on someone else's work
i have FAR more respect for Archimedes, Newton, Franklin and of course, Einstein

[xanatose]

I believe that Edison was a firm believer in sweat shops. And in taking his workers ideas and place patents upon them.

He was the equivalent of the modern day CEO. "Take credit of other peoples work. And make a ton on money while paying peanuts."

[hutch--]

There is the situation in Tasmania that they have an excess of power and not enough industry t use it so they sell some of it to the mainland. Apparently they use a very high voltage DC line under Bass Straight to Victoria which appears to work OK, I don't claim to userstand why its done as high voltage DC but apparently there are technical gains in efficiency terms from doing so.

[dedndave]

i'll come down there, only if i get to stay with Rachael Taylor   :P

[FORTRANS]

There is the situation in Tasmania that they have an excess of power and not enough industry t use it so they sell some of it to the mainland. Apparently they use a very high voltage DC line under Bass Straight to Victoria which appears to work OK, I don't claim to userstand why its done as high voltage DC but apparently there are technical gains in efficiency terms from doing so.

Hi,

   In the article I mentioned earlier, high voltage DC has lower
losses and better control than high voltage AC.  A quote out of
context "...less than half the alternating-current losses at the
same voltage."  They also allow power to be transferred from
one power grid to another without synchronizing problems
(phase and frequency).  The required conversion to AC adds
some pluses and minuses of course.

Regards,

Steve N.

[dedndave]

i don't think that is strictly true
however, i can see where DC might be very advantageous in an underwater environment
a lot of things come into play - transmission distance, wire used, voltage and current, of course
but the surrounding environment also makes a difference
when you say "high voltage", i have to ask "how high" - lol
comparing 10 kV DC to 10 kV AC is like comparing apples and oranges in many respects

in DC circuits, the loss is primarily due to simple wire resistance, assuming that the insulation is adequate
in AC circuits, calculating losses is somewhat complex

[FORTRANS]

Hi Dave,

i don't think that is strictly true

   ?

however, i can see where DC might be very advantageous in an underwater environment
a lot of things come into play - transmission distance, wire used, voltage and current, of course
but the surrounding environment also makes a difference
when you say "high voltage", i have to ask "how high" - lol
comparing 10 kV DC to 10 kV AC is like comparing apples and oranges in many respects

   Dang, you went and wanted context.  And I wanted to limit
typing.  "Muntz calculates that the same 100-mile line loaded
with the same 800 MW, but operating at 500 kV, would lose
3.82 MW, less than half the alternating-current losses at the
same voltage.  Push the line up to 800kV,and losses drop to
1.5 MW, also less than half for a 765 kV alternating current line."

   In his maps, the lowest voltage is "230-kV AC".

in DC circuits, the loss is primarily due to simple wire resistance, assuming that the insulation is adequate
in AC circuits, calculating losses is somewhat complex

   Hm, he does have a, to me, strange comment.  "...  In
these cases, direct current was selected because it is efficient
and controllable.  Alternating current follows the path of least
resistance, buzzing along random wires like water on a mountaintop
trickling down various streams to pool at the base.  A direct-current
line is like a pipe from top to bottom, with a pump that can be
adjusted in real time."  Simile for effect?

Anyway,

Steve

[dedndave]

well - there is loss, then there is voltage drop
at any rate, i can't imagine what the heck you would do at the end of the wire with 500 kV DC - lol
there are no tubes or sold state devices that can switch that
with AC, you use a step-down transformer, which may be as good as, let's say 75% efficient, tops
anything you do the high-voltage DC is likely to be in the neighbourhood of ~50%

[FORTRANS]

at any rate, i can't imagine what the heck you would do at the end of the wire with 500 kV DC - lol
there are no tubes or sold state devices that can switch that
with AC, you use a step-down transformer, which may be as good as, let's say 75% efficient, tops
anything you do the high-voltage DC is likely to be in the neighbourhood of ~50%

Hi Dave,

   You should read the article.  Rats, their site just has a
summary.  It might make a big bug zapper?

   "...  That is because special converter stations are needed
at each end to change alternating current to direct current and
back again.  The conversion requires massive electronics that
eat up about 1 percent of the electricity at each end. ..."  The
photograph of one does have that massive look to it.

Regards,

Steve N.

[dedndave]

i must be a crappy engineer - lol
the best DC to DC switcher i ever designed was about 80% effecient - 85% tops (under the right conditions)
i was damn proud of myself, too   :P

fortunately, power distribution is not really my forte'
i usually design analog, digital, and RF circuits
in spite of the fact that i started out playing with radios, i would say RF is my weakest of the 3   :P

[hutch--]

Let me see if I have this right, any transmission conductor (power line) has both capacitance and inductance which leads to a rise time with voltage change (I know this from electromagnets and DC brush motors where you have the hysteresis characteristics but that is also subject to the steel cores [ in transformers ] ).

Now I am guessing but high voltage DC does not have the sign inversion and thus voltage change so it misses out on the inductive and capacitive losses ?

[dedndave]

it isn't a simple thing at all - lol
but, in AC circuits, a transimission line may be viewed as a series of "lumped elements"

this image demonstrates an "unbalanced line"
for balanced transmission lines, there would also be inductive elements in the lower "arm"

impedance matching, standing waves, and a variety of other math fun comes into play

we usually use a smith chart to do the math for us   :P

http://it327.groups.et.byu.net/images/Smith%20chart.jpg

this is a bit of a simplification, but easier to understand...
in a DC circuit, you will lose voltage due to resistance in the wire
the power lost is P = E x I, where E = voltage drop and I = load current
in an AC circuit, you lose both voltage and current together

now that i remember a little better, they originally chose AC current because
it was easier to distribute while maintaining nearly the same voltage

as voltage drop accumulates, they put a transformer in and everyone is happy again

but, there are other reasons also
AC is much more "natural" when it comes to converting mechanical energy (like Niagra Falls) into electrical energy
the rotating field windings in the generators want to put out the sinusoidal wave we are all familiar with

far more efficient than a DC generator