440VAC 3 phase is not common in the US. 480VAC is common in the US
It's really the same thing.
When you're talking about industrial power distribution numbers like 440 or 480 should be thought of as referring to a category rather than a specific voltage. The devices that are made to work with that kind of power assume that actual values could range anywhere from about 430-490 since in practice there is a large amount of variation, especially in older facilities.
but reliably at 132kV? It aint easy, cheap and certainly neither if you want efficiency.
Nothing that involves large amounts of power at 123 kV is cheap.
Even if a solid state substation is initially more expensive to build than a traditional substation that's a sunk cost while the efficiency gains of using DC accrue every day.
Now for even more fun figure out how much deviation is acceptable from the nominal value of 12V with it comes to what a motherboard will accept then consider how long the longest wire run is from your central power supply to the furthest computer.
Now consider that the voltage must be maintained within the tolerance band with the load ranging anywhere from 1 computer operating to all of them operating. From that you can calculate the highest acceptable resistivity of the wires. Remember since you're distributing from one point to many you need to keep voltage in tolerance for any combination of loads operating - you can't just raise the output of the power supply to compensate for the line losses and call it good.
Once you've figured out this maximum acceptable resistivity you can figure out how large your wire must be (hint: it's going to be a lot larger than 12 AWG).
Yes, the current will be higher at lower voltage. This does NOT correlate to needing thicker wires, as the wire has to withstand not current but power which is the result of multiplying voltage with current.
You've managed to be right while also being wrong at the same time.
You could use voltage*current to calculate the thermal losses in a conductor but what you've done incorrectly is assume that "voltage" in this equation is the voltage between the conductor and ground.
The correct way to calculate losses in a conductor is current * end-to-end voltage difference
The end-to-end voltage difference is directly proportional to the current so the most efficient way to calculate the losses is current squared times resistance.
Since the surface area of a wire is proportional to the square of the wire diameter and the conductivity required is proportional to the square of the current carried it ends up that wire diameter is directly proportional to the current.
It's a matter of how many watts you expect to supply and how large the wires must be to supply that power at 12 volts while maintaining the voltage at the outlets within an acceptable range.
Look up the rating of the power supply currently operating your computer then calculate how many amps would be required to deliver that power at 12 volts. Look up the gauge of wire that would be required to supply that much current without melting the insulation. Then multiply by the number of computers in a typical data center.
AC was the answer to how to transport electricity long distances
AC was used because using transformers to convert between voltage levels was more efficient than motor-generators and solid state electronics hadn't been invented yet. All other things being equal, DC is always more efficient than AC for long distance transmission.
I thought that only the government could protect consumers from the evil, evil business owners.
How is it possible that a group of capitalists are getting together and finding a ways to eliminate a problem and better serve their customers without some bureaucrat forcing them to do it?
Think of "government" as an umbrella term that encompasses a number of factions, not all of which have exactly the same specific agendas but all share the same overall goal of extracting resources from the citizens for their own benefit.
Big brother doesn't care too much about the average citizen. He's interested in getting information that can be used to blackmail those with resources or influence.
The biggest design above is the "super" Orion design; at 8 million tonnes, it could easily be a city.[7] In interviews, the designers contemplated the large ship as a possible interstellar ark. This extreme design could be built with materials and techniques that could be obtained in 1958 or were anticipated to be available shortly after. The practical upper limit is likely to be higher with modern materials.
I find all the BS that gets thrown around about how technology from the middle of the last century like space travel or fourth generation nuclear power is "only X decades away" rather annoying. It makes me feel like we're living in decline portrayed in the Foundation novels.
So how is flux pinning going to stop the train from tipping over if the base that holds the magnets tips over due to the soil supporting it becoming unstable?
Did they have superconductors that worked at liquid nitrogen temperatures in 1980? The amount of energy needed to keep nitrogen liquid is significantly less than what it takes to keep helium liquid.
Slashdot Mirror
It's really the same thing.
When you're talking about industrial power distribution numbers like 440 or 480 should be thought of as referring to a category rather than a specific voltage. The devices that are made to work with that kind of power assume that actual values could range anywhere from about 430-490 since in practice there is a large amount of variation, especially in older facilities.
AC motors are more efficient than DC motors, but then again that really means three phase AC motors instead of single phase kludges.
That's only true for large values of "12" that approach 300. It is a very big battery though, and they will reliably handle discharges at over 1 MW.
Why? Because there are only two wires instead of three?
The last washing machine motor I looked at had multiple windings to achieve different speeds rather than using a VFD.
Nothing that involves large amounts of power at 123 kV is cheap.
Even if a solid state substation is initially more expensive to build than a traditional substation that's a sunk cost while the efficiency gains of using DC accrue every day.
Now for even more fun figure out how much deviation is acceptable from the nominal value of 12V with it comes to what a motherboard will accept then consider how long the longest wire run is from your central power supply to the furthest computer.
Now consider that the voltage must be maintained within the tolerance band with the load ranging anywhere from 1 computer operating to all of them operating. From that you can calculate the highest acceptable resistivity of the wires. Remember since you're distributing from one point to many you need to keep voltage in tolerance for any combination of loads operating - you can't just raise the output of the power supply to compensate for the line losses and call it good.
Once you've figured out this maximum acceptable resistivity you can figure out how large your wire must be (hint: it's going to be a lot larger than 12 AWG).
You've managed to be right while also being wrong at the same time.
You could use voltage*current to calculate the thermal losses in a conductor but what you've done incorrectly is assume that "voltage" in this equation is the voltage between the conductor and ground.
The correct way to calculate losses in a conductor is current * end-to-end voltage difference
The end-to-end voltage difference is directly proportional to the current so the most efficient way to calculate the losses is current squared times resistance.
Since the surface area of a wire is proportional to the square of the wire diameter and the conductivity required is proportional to the square of the current carried it ends up that wire diameter is directly proportional to the current.
Excellent idea! Hydrogen gas, oxygen gas, chlorine and an ignition source all in the same package. What could possibly go wrong?
It's a matter of how many watts you expect to supply and how large the wires must be to supply that power at 12 volts while maintaining the voltage at the outlets within an acceptable range.
This is equally true of both AC and DC.
We have these things now called semiconductors. You may have heard of them.
Look up the rating of the power supply currently operating your computer then calculate how many amps would be required to deliver that power at 12 volts. Look up the gauge of wire that would be required to supply that much current without melting the insulation. Then multiply by the number of computers in a typical data center.
AC was the answer to how to transport electricity long distances
AC was used because using transformers to convert between voltage levels was more efficient than motor-generators and solid state electronics hadn't been invented yet. All other things being equal, DC is always more efficient than AC for long distance transmission.
I thought that only the government could protect consumers from the evil, evil business owners. How is it possible that a group of capitalists are getting together and finding a ways to eliminate a problem and better serve their customers without some bureaucrat forcing them to do it?
That group of people isn't going to be subject to lock-in because it's so easy to get IPv6 connectivity from tunnel brokers.
Windows 98
Do you think a significant proportion of their users actually would know or care what the difference is?
Using some kind of password manager, either a third-party service or a local application, would make that kind problem easier to solve.
Think of "government" as an umbrella term that encompasses a number of factions, not all of which have exactly the same specific agendas but all share the same overall goal of extracting resources from the citizens for their own benefit.
Big brother doesn't care too much about the average citizen. He's interested in getting information that can be used to blackmail those with resources or influence.
Project Orion
I find all the BS that gets thrown around about how technology from the middle of the last century like space travel or fourth generation nuclear power is "only X decades away" rather annoying. It makes me feel like we're living in decline portrayed in the Foundation novels.
So how is flux pinning going to stop the train from tipping over if the base that holds the magnets tips over due to the soil supporting it becoming unstable?
Did they have superconductors that worked at liquid nitrogen temperatures in 1980? The amount of energy needed to keep nitrogen liquid is significantly less than what it takes to keep helium liquid.
Looks like a case of cold feet.
I wasn't sure if it was some kind of really clever pun or an error.