TESLA VS. EDISON

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ActionDave said:
It is true that Beta was the best, but it was Sony's business plan, not marketing on either side, that brought them down. They wanted to vertically integrate their product line; can only use a Sony tape in a Sony player. They learned their lesson and did not try the same thing with Blue Ray.

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We had Beta on my submarine for our movies :)

I think they did try the same thing for Blue Ray but failed yet again.
 
I highly reccomend Empires of Light it is an excellent read. The animal demonstrations were conducted by a man named Harold Brown who allegedly had no affiliation with Edsion. That was later found to not be the case. I agree this was the begining of the Edison downfall.
 
Steinmetz

Steinmetz

Steinmetz who worked for GE (started by Edison) is the guy who developed three phase systems. It lead to simple efficient motors which is what eveyone wanted.
 
ActionDave said:
Still makes my point. Sure there are some things that DC is better for but those are limited, which is why the world uses AC.

That is a consumer item compared to a commodity so you can't really compare.

It is true that Beta was the best, but it was Sony's business plan, not marketing on either side, that brought them down. They wanted to vertically integrate their product line; can only use a Sony tape in a Sony player.
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You may separate marketing from business plan, but to me it's different sides of the same coin. My point is that the superior technology does not necessarily win the day in the marketplace, whether it be consumer item or commodity. As for AC being better than DC for most things, I'm not sure I agree with that, either.
 
ActionDave said:
Sure there are some things that DC is better for but those are limited, which is why the world uses AC.
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Well, that's a move in the right direction. Good for some things as opposed to saying DC isn't used.
AC is convenient for LV distribution. Voltages can be transformed to convenient levels and switching is less onerous.
But the use of DC might be more ubiquitous than you realise.
Pretty much all electronic equipment, computers, televisions, mobile phones, monitors, land lines, printers, DVD players, modems, vehicles, battery powered tools........stuff.
Still think DC is of limited use?
 
For the OP:

We need AC for several reason.

1) First is transmission; to haul power hither and yon, you want the losses as low as possible. To that end, we use as high a voltage as feasible. [And that answer varies with the length of the transmission line; from 13KV to 500 KV...] To get that HV AC transmission, we use transformers, haul HV/low current AC, and at the far end use another transformer to make {typ.} 240/120VAC.

We have no easy way to get HV/high power DC from LV DC or vice versa. Until late, we had no way at all.


2) Motors. Tesla invented polyphase AC and AC motors. As compared to DC motors, AC induction motors are simpler, smaller, cheaper, easier to cool, FAR more reliable, and have longer lifetimes. They have one gotcha, below.

Now, in very recent times [~25 years..] high voltage/high-power semiconductors have become readily affordable.

With same:


3) We can afford to turn HV AC into HV DC, and transmit it; then make HV AC (and then MV/LV AC) again. This has several pluses:

a) The insulation on a powerline is for peak voltage. On a DC line, peak== average, so with given insulation, you can run a higher voltage/lower current/less losses.

b) Losses are lower. AC lines have somecapacitive losses DC lines don't

c) The "60 Hz" at both ends are independent in freq and phase. This is amajoradvantage on a line joining two grids.


4) The major gotcha of AC induction motors is they rotate at a speed fixed by the line freq. [No, I'm not going to delve in slip here....] while DC motors are variable speed.

BUT the same semiconductors let us take 60Hz AC, make DC, and THEN make AC of whatever frequency we need. The gadget is a "VFD" - variablefrequencydrive and they are DIRT CHEAP.




Yes, Tesla was a $&^#$&^ genius. I had a prof who'd met/work under him and he was in awe of him.
 
Well Tesla was and still is a topic . Iam a fan most electricians should be .

Its interesting to me but maybe not to some but reading old patents .

Its fun to see what was made and a lot will never see even today .

I actually have read some of his patents you can go online to the US Patent office and sign up to view or request these its free you need a customers control number and apply for that but also some are not public still today .

What were told and teach in US schools is not what in some cases was solid facts about who invented first .

If you ever take the time to read some old patents and just read some of the things that were invented before they made it to the public you would be amazed .

Not just Tesla theres hundreds of folks we will never know .

We only see whats in front of us but theres many folks who we never will know there names its old history and its there but you have to find it .

Its funny but there was a few patents that Tesla wrote and the old story from the patent office was they could not fully understand what he was inventing no one at that time had that knowledge in that area or a clue so what ever he said they could not reject it because they didnt know what he was claiming was his invention or how it worked .

I would have enjoy see the patent examiner with that blank look on his face .
 
ohmhead said:
Well Tesla was and still is a topic . Iam a fan most electricians should be .

Its interesting to me but maybe not to some but reading old patents .

Its fun to see what was made and a lot will never see even today .
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Get "The Complete Patents of Nikola Tesla", published by Barnes & Noble. 535 pages of every patent Tesla was granted. Good stuff.
 
By the way, on the "Tesla" vs. "Edison" debate, one good subject is "fun". What "fun" is it reproducing Edison's inventions vs. Tesla's? Well, once you cobble together a "Tesla Coil" from a few $10s of reused components, and have 10" sparks flying, can suck sparks through coffie cups, and light up florescent tubes through "human conductors" of 6+ people, Tesla definitely wins! :) And that's not even mentioning the pinhole RF burns that freely tattoo whatever parts of your body come close! ;)
 
Besoeker said:
Well, that's a move in the right direction. Good for some things as opposed to saying DC isn't used.
AC is convenient for LV distribution. Voltages can be transformed to convenient levels and switching is less onerous.
But the use of DC might be more ubiquitous than you realise.
Pretty much all electronic equipment, computers, televisions, mobile phones, monitors, land lines, printers, DVD players, modems, vehicles, battery powered tools........stuff.
Still think DC is of limited use?
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I get it and agree; horses, courses and voltages included.
 
Open Neutral said:
4) The major gotcha of AC induction motors is they rotate at a speed fixed by the line freq. [No, I'm not going to delve in slip here....] while DC motors are variable speed.

BUT the same semiconductors let us take 60Hz AC, make DC, and THEN make AC of whatever frequency we need. The gadget is a "VFD" - variablefrequencydrive and they are DIRT CHEAP.
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A couple of points.

DC motors are not naturally variable speed. You need control equipment to make them so. For all but very small machines this usually requires power semiconductors. If power the source is AC, then usually it will be SCRs. From DC, it will be a chopper of some sort and probably use IGBTs.

Variable frequency inverters mostly use IGBTs as the switching devices. The majority of HVDC systems use SCRs.
 
AC was chosen many years ago since the voltage is easily altered with a simple transformer.
Power may be generated at a fairly low voltage, often a few thousand volts, and stepped up to hundreds of thousands of volts for long distance transmision.
Near the point of use, the voltage is easily reduced to 120,208,240,277,480 or any other desired voltage.
Also the voltage could be easily reduced to a still lower and very safe voltage for childrens toys, door bells, festive lighting etc.
Within an appliance, the voltage may easily increased if required, for example for the HT supply for a radio.

Untill recently the voltage of a DC supply could not be altered without rotating machinery.
If DC was to be used in the home etc, then this required either a power plant for every city block, OR transmission at a higher voltage (AC or DC) and local substations with rotary converters.
Moving machinery requires more maintenance and has greater losses than a simple transformer.

DC was a bit more popular in the UK since the higher voltage reduced the number of substations.
Even after the general use of AC, some utilities still provided DC service until recently.
Certainly parts of New York still had DC service until a few years ago.

Technology however moves on, and with modern power electronics it is entirely possible to alter the voltage of DC supply cheaply and with little loss.
Very high DC voltages are now routinely used for bulk power transmission over long distances.

We may yet see a return to DC especialy in large data centers and the like.
Modern IT equipment with switched mode power supplies will accept AC or DC, and the provision of back up supplies is much easier with DC.
It would be a simple matter to parralell several DC supplies via blocking diodes, no concerns about synchronising or closed transition switching.
 
Synchronization, Distance and Prodigal

Synchronization, Distance and Prodigal

"Prodigal Genius, the Life of Nicola Tesla" is a good book. A tad older but written by someone closer to him.

DC is beneficial for long tranmission lines because at 60Hz, a long line starts to approach 1/4 wavelength and becomes an antenna. Standing waves can be a problem.

DC is used to move power between two unsynchronized systems: 50Hz-60Hz, regional grids. There are even zero-length DC links just for that purpose.

But, the brilliance is the rotating magnetic field; a stroke of genius.
 
Besoeker said:
A couple of points.

DC motors are not naturally variable speed. You need control equipment to make them so. For all but very small machines this usually requires power semiconductors.
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Look up PCC streetcars & the XD-323. They had variable speed motors before the word "semiconductor" meant something other than one half of a NYCTA employee.

http://www.youtube.com/watch?v=4EA_M3A36Qk
 
beanland said:
"Prodigal Genius, the Life of Nicola Tesla" is a good book. A tad older but written by someone closer to him.

DC is beneficial for long tranmission lines because at 60Hz, a long line starts to approach 1/4 wavelength and becomes an antenna. Standing waves can be a problem.
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The feed from Hoover Dam to LA had a intermediate station added mid-run; care to guess why?

DC is used to move power between two unsynchronized systems: 50Hz-60Hz, regional grids. There are even zero-length DC links just for that purpose.
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Indeed. Our nation's power grid is touchy enough. DC-DC lets us run async links between the various sections.

But, the brilliance is the rotating magnetic field; a stroke of genius.
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Which he was.... If you're a Fringe fan; Walter is but a disciple of Tesla...
 
Open Neutral said:
Look up PCC streetcars & the XD-323. They had variable speed motors before the word "semiconductor" meant something other than one half of a NYCTA employee.

http://www.youtube.com/watch?v=4EA_M3A36Qk
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It's still a DC "drive" system though, it just didn't use semiconductors as we know them today. It was a resistance ribon and a 99 position switch. In other words it was not the MOTOR that was inherently variable speed, it was HOW you applied power to it that made it so. That is the same as it is with AC motors now. The only difference really is that the technology for allowing this to happen with AC motors took longer to come about.
 
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