Evolution Of Alternating Current Power In The U.s.

This is a very interesting observation.

First lets remember that there are many energy sources in our houses including but not limited to high power electrical devices, natural gas / propane gas appliances, fuel oil, etc.

There are regulatory standards that are available to try and ensure that these devices meet safety standards.

Sometimes these are not sufficient when first "regulatory approved". Good example is drip coffee makers of a couple of decades ago when it was found that the secondary one shot thermal cut off could fail in about 1 or 50,000 cases. This seemed acceptable until there were millions of coffee makers being produced. So the UL and other regulatory standards were changed to include two series and different over temperature fuses. This was successful.

So called Lithium batteries that Tesla is proposing are actually Lithium Ion batteries. These do not contain any metallic lithium.
Metallic lithium is very reactive and indeed is in lithium primary cells. They do however have a flammable electrolyte.

Having said this when something goes wrong with either over discharge or over charge of Lithium Ion cells, then things can go wrong. Metallic lithium can be plated out. Also if over charged, these cells can go into thermal runaway. Under this condition we have sort of the perfect storm. The cell has a flammable electrolyte and the thermal runaway condition produces oxygen. So we have a source of ignition, fuel and lots of oxygen. This is a very difficult situation to extinguish, and some strategies are to just let it burn out.

In order to be safe the battery management systems for Lithium batteries have two separate and independent monitors to ensure that bad things don't happen.

A number of years ago we would see videos of laptops and and cell phone infernos. Haven't seen those lately.

I can only assume that Tesla is aware of this and will provide appropriate battery management, and also meet appropriate regulatory approvals.

David
 
According to Wired magazine, Tesla has partnered (more or less) with Panasonic to manufacture their batteries. I can see this turning into a dedicated manufacturing facility doing nothing but car batteries. I would guess that the other players in the electric car business are taking similar steps.

That said, Tesla (and others) are relying on the expertise years in development held by these battery makers. Since they have been in the loop with UL, etc, I can only hope that there are checks and controls within that industry to keep regulations and insurance underwriting current. For years, people have had SLA battery banks as home backup, and they I am sure pose their own hazards. Likely these have been vetted as much as possible and regulations are in place to mitigate the risk to homeowners. So it's a matter of one side of the coin keeping up with the other.
 
Actually, Panasonic just makes the cells. Tesla is currently building a massive plant out by Reno to assemble the Battery packs. Those things are pretty impressive :) But each indiviual cell is pretty much the same kind that is used in the newer Lithum power tool packs, just imagine a 600V cordless drill with a 200 lb battery pack :) I'd say more, but I Tesla and Elon are pretty secretive about what goes into those packs.
 
Oh what an interesting forum this has turned out to be, from a discussion of a little gold mining town in Colorado and its first demonstration of Alternating Current and its triumphs. Giants like Thomas Edison, George Westinghouse, and Nicola Tesla, to the latest massive efforts by the visionary Elon Musk , not only with his Tesla automobiles (again, try one, you will like it), but also the largest solar cell provider in the nation and whose battery giga-factory is already sold out through most of next year. These are all Direct Current applications that produce and/or use electricity in the same location it comes from, without the long transmission lines. AC is not dying, and will probably be with us well into the future. Its just that a lot of the power needed for many applications is starting to be generated and or stored on site. In some cases such as automotive applications, the switch isn't from AC to DC, but from gasoline to DC for instance, and even there, the battery charging stations are run off of the AC grid. Back when I was was a kid in the early 50s, I remember going to exhibitions that were pushing for nuclear power showing a 'not too distant future' where every house and car would have a very small nuclear reactor that would provide all of its energy needs. Later on I remember the push for space bases solar power stations that would beam power directly to a little antenna on your roof.
Just a hint of these two technologies exists today.

Now, lets get back to swarfing!

Chuck the grumpy old guy
 
Edison may get his revenge. They are getting the preliminary legal stuff done to build a multi state DC power line by me. Grain Belt Express. Public meetings etc. I think they told me 1 million vdc. Feasabillity? Contrary to what I was taught.
 
It is interesting to note the technological time frame for distribution of HVDC power; I gather it is relatively new on large commercial projects, my thinking is that new materials and technology have created the "re -emergence" of DC Power. If Henry Ford would have had modern hydraulics the Model T may have had an automatic transmission.

A personal note on the Ames Power Plant, in the early 1930's my father sold and serviced small electrical generators prior to becoming manager of Grand Valley Rural Power Co. at Grand Junction, CO. The development of AC power was essentially a developing (new) science at that time. He told me some of the story about Westinghouse developing the hydro-electrical plant; the Hydro Power video about it added a lot more detail.

Have a good day

Ray
 
There are actually a couple of advantages to HVDC Transmissoion lines:

1) No skin effect. Even at 60 Hz, the Ac uses mostly the outside of a conductor. So a DC line has slighly higher current capacity for the same wire size
2) No need to keep the generators on sections of the grid in sync. In fact, alot of HVDC links are relatively short ones used to connect different parts of the power grid toghether.

I think that modern solid state switches are the main driver for the emergence of HVDC.

I also think that soon we will start seeing low voltage DC wiring in houses to run LED's and other low power items. It seems silly to have all these tiny transformers in every outlet instead of one more efficient one in the fuse box.
 
hvontres said:
I think that modern solid state switches are the main driver for the emergence of HVDC.
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+1! The ubiquity of these devices has dropped the cost to the point where transformers are a second choice. As acceptance increases, the volume will go up and prices will drop even further.
hvontres said:
I also think that soon we will start seeing low voltage DC wiring in houses to run LED's and other low power items. It seems silly to have all these tiny transformers in every outlet instead of one more efficient one in the fuse box.
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+1 again! Some years ago, I elected to light our newly remodeled kitchen with LED lighting. At the time LED area lighting was cutting edge and the were no practical luminaires available so I designed my own (it was the justification for getting my Tormach PCNC ;)). The primary driving design criterion was to design an energy efficient system. To that end, I elected to run a 200W 30 volt DC switching power supply running to local constant current bucking drivers running series-parallel arrays. Altogether, I am driving 91 - 1 W spots and under-cabinet arrays consisting of 111 - 1/4 W LED's in total. For bounce lighting, I ran 12 volt strip lighting consisting of 256 LED's from a separate 100W 12 volt switching power supply. The bus wire runs for both were more than 35 feet, so power line losses were a concern in the effort to maintain reasonable efficiency. 12 ga. wire was used for the 12 and 30 volt bus lines.

It seems that the current trend is to have all the small electronics run from USB ports which will go a long way to wards a low voltage standard. I have already seen 120 vac receptacles with USB ports built in. Kind of a small jump to running low voltage from a central hub to the receptacle and eliminating the local switching supply.

Bob
 
RJSakowski said:
It seems that the current trend is to have all the small electronics run from USB ports which will go a long way to wards a low voltage standard. I have already seen 120 vac receptacles with USB ports built in. Kind of a small jump to running low voltage from a central hub to the receptacle and eliminating the local switching supply.
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Ok for a few watts but beyond that it's cheaper to install point of load switchers. You don't want to replace all the #12 in your walls with #000.
 
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