Do you think AC will ever be widely replaced with DC?

[sportage]

Are these The same people that vote in our government officials?
Decide who should marry who?

God forbid, we are truly doomed.

As anyone knows that ever attended a public school not to mention private scrolling, but not necessarily home skoolin, which is quite obvious in this case...
As the bible starts out, IN THE BEGINNING there was only DC power.
Then what's his name invented the electric light, that thing that looked like a big lightening bug, and wired the city streets with lighting, it was DC powered.

So why didn't this work?

The costs of powering using DC. Btw... U do know DC stands for direct current? (Just asking)
Anywho... DC power long distance required numerous power stations because the resistance of the copper wire doesn't work very well with DC current.
AC is more feasible, cheaper, and transmits long distance, unlike DC.

So (why bother but what the hell) so, reverting back to DC would be returning to those early days when the electric lamp was first invented.
In other words, AC is the miracle solution to,power the nation.
Not DC.

Why do we get suckered into this stuff???
I'm not,even going to spell check. Who cares?

 

[PowerEngineer]

Strangely enough, I just ran across this article on old DC distribution in San Francisco which may be of interest to posters in this thread:

http://spectrum.ieee.org/energy/the...echalert&utm_medium=email&utm_campaign=112112

Enjoy.

 

[UberNeuman]

It comes down to the question of "who made who"?

 

[IGBT]

the eco-KOOKS want to get rid of both of em.

 

[bradley]

Strangely enough, I just ran across this article on old DC distribution in San Francisco which may be of interest to posters in this thread:

http://spectrum.ieee.org/energy/the...echalert&utm_medium=email&utm_campaign=112112

Enjoy.

One of the coolest links posted here in a long time. What a revelation. Thanks!

 

[IronWing]

the eco-KOOKS want to get rid of both of em.

Whenever I read your posts I hear Eeyore reading them aloud.

eco-Kooks most certainly don't want to get rid of either. They just want to generate electricity via pixie dust swished by unicorn tails.

 

[Anarchist420]

You don't know anything about electricity, do you? I want you to look at what I've bolded above and think about why that may, in fact, be an advantage of AC.

I was thinking that when I posted it. I also was thinking that DC isn't necessarily cleaner than AC, but I didn't know why and I still don't and I won't see the whole picture much less be able to analyze it.

Also, the number of appliances and other devices that would cease to work because they're built to operate on AC only - at this point, it'd be near impossible to switch.

You're right on that one... the fact that savings will be so low means that so few would be able to buy replacements PCs, TVs, washers, dryers, gamecubes, battery chargers, etc., etc. As for the others, the devices weren't meant to be DC powered or the traces were routed poorly/something or lack thereof was causing poor EMI or RF rejection, and/or something else.

Yes, they would have to tear my house down to make it 100% DC compatible and I'd miss the house I have.

The problem is that prices of monitors, TVs, iceboxes, washers, dryers, etc., etc. would have to go up if electrical circuitry were made to reject AC input ripple with no sacrifices other than high cost... the market could better do it on it's own as long as there was no govt interference but the leviathanic energy star stickers are everywhere and about half of the people will buy what has an energy star sticker or what it approved by the govt... there is also a temptation to get regulations in favor of the self if you create a standard loved by the self. That would decrease human happiness because most people don't care and it would make things above market prices.

Perhaps there should be different levels of ATX standards or something like that based upon how good the circuitry is... i don't like how things I buy are simply pass/fail. The reviews from professional hardware sites do a good enough job though.

 

[Jeff7]

Whenever I read your posts I hear Eeyore reading them aloud.

eco-Kooks most certainly don't want to get rid of either. They just want to generate electricity via pixie dust swished by unicorn tails.

I don't think you capitalized that properly.

 

[IHateMyJob2004]

1) Three phase motors are the most efficient kind. They require AC.
2) Converting AC to DC is cheap and easy. Converting DC to AC is not cheap and easy
3) Transmission lines would become hugely inefficient due to problems with impedance.

Want more?

 

[Anarchist420]

1) Three phase motors are the most efficient kind. They require AC. 2) Converting AC to DC is cheap and easy. Converting DC to AC is not cheap and easy 3) Transmission lines would become hugely inefficient due to problems with impedance.

1. Efficiency isn't everything.
2. for where long transmissions lines are desired, those devices could use AC... I'm not saying that the State should regulate anything, I'm just saying AC isn't as good because it inherently isn't as clean... it causes more fluctuations than DC does.
3. professionals could create solutions to that problem. Perhaps we could get some optical, solar, wind, and/or laser form (or something else) of energy in between and then the impedance problems would be reduced.

 

[BUTCH1]

Uhh...high current, low voltage is MUCH more expensive to deal with (thicker conductors), and high voltage DC is insanely dangerous for your average idiot due to the arc factor. DC is making a comeback in utility-scale settings (and low-power battery-operated devices), but AC continues to be the best, safest, and cheapest way to power a household.

Uhh, I thought "low power battery operated devices" were always DC, unless Tesla invented an AC D cell we haven't seen yet..

 

[BUTCH1]

I'm not quite sure what you're trying to say, but you're not correct.

220V is the RMS voltage (root mean square voltage.) If you're thinking that the voltage looks like a sine curve, oscillating between negative 220V and positive 220V wrt ground, you've been mislead somewhere. It's actually higher than that. 220 volts is the root mean square voltage, more or less an "average" voltage that is used for calculating power. For a purely resistive load, the power you use = voltage times current. So, if you needed 1100 watts, you'd need 220V at 5 amps. To get the same amount of power (energy per unit of time) with DC, you'll still need 5 amps @220V. Or, any other combination whose product is 1100 watts. (440V, 2.5 Amps, for instance.) If you drop the voltage, you're going to have to increase the current. Since the power losses are I²R, you're going to need bigger wires (equals more expensive.) As you can see from the video I posted above, there's a slight problem with handling higher DC voltages. So, you can go lower voltage, which means thicker wire to handle the increase in current.

Those elements seemed to glow a little brighter when hooked to DC but what your saying makes sense since I have a 1500W space heater that uses 13 amps at full power..

 

[Muse]

I'd like to see houses have AC outlets alongside DC outlets that have smart voltage switching. So if you have a computer, you can plug into the DC receptacle and feed your computer 12 volts (it can reduce it to 5V or whatever inside the case). And then things like lamps can just have simple LED bulbs that run off the DC, instead of having each bulb have its own transformer.

I could see these being smart enough to use some sort of communication method to switch to the proper voltage depending upon the device being plugged in, maybe by some simple query or an RFID chip in the plug.

Sounds like science fiction that could become science fact... my favorite kind.

 

[Muse]

definitely thought this thread was about atlantic city and our nations capital.

It isn't? :$

 

[Thebobo]

DC is shit. Everything should run on three-phase 480v AC.

YEA that's a manly voltage!

 

[skyking]

All ribbing aside, this has been a cool thread thanks to some thoughtful links.
My dream house will have DC lighting circuits direct to LEDs. A small solar array and modest battery bank. When the power goes out, just having light is a big bonus. Passive and active solar heating will round it out, and if any pumps are involved for hydronic heating, those would be DC as well.

 

[CZroe]

Even if we solved the transmission losses, DC off the grid would still have plenty that needs to be cleaned up.

What I've always wanted was a standardized external switching PSU that I could connect multiple appliances to. For example, my TV with all the classic video game consoles connected to it uses a ton of outlets and the efficiency losses from each having a different power transformer multiply. The Sega Genesis with all the accessories alone uses three bricks and a plug (console, Sega CD, Sega 32X, TV). One high-capacity "brick" plugged into the AC source with DC wires to each device would be far more efficient.

What I want is some kind of switching PSU shaped like another home theater component* with enough capacity to run multiple devices simultaneously but with some kind of modular cable system going to all the DC in jacks on the different devices. I could probably make something like this for all the DC stuff, but it would have to be standardized for to work with things with internal rectifiers (TVs) or non-standard DC in jacks (XBOX 360).

*I've seen UPS units and over-prices surge suppressors like this.

 

[Rubycon]

DC is shit. Everything should run on three-phase 480v AC.

Try 400Hz for size.

Imagine having 25Hz power.

Does anyone remember those party bulbs from the 70s? They have a big, lazy filament and in the middle post there was a small alnico bar magnet attached. The AC frequency would act on this field causing the filament to wiggle back and forth like a tubifex worm under stress. They were available in different colors too. Today we just have boring LED bulbs that change color. At least they last longer.

As far as frequency you can try this experiment. If you have a computer you have a function generator. Just connect your sound card to a suitable amplifier and you're all set. Receivers and home audio gear are OK but a PA amp is usually better suited as it has more power and is more robust.

Connect the output terminals to an appliance. It needs to be on the small side for a home receiver in the 100WPC range for sure, whereas QSC PowerLight, Crown I-Tech, etc. will power larger devices like power tools, vacuum cleaners, etc.

Do be advised that this has the potential to destroy just about everything if something goes wrong, but that's what makes these kinds of things fun, right?

If you start with a 60Hz sine wave your device will run normally. Of course the amplifier will need to have sufficient voltage (120V) on its output terminals and most receivers won't do this. However that does not mean it won't work. Power drills, small vacuum cleaners, sewing machines, etc. have universal motors that will work with far less voltage. Try different waveforms such as square wave, triangle, sawtooth, etc. to see how it affects the run and start performance.

Finally try different frequencies. Most universal motors will run quite a ways outside of 50/60Hz of their nameplate but do remember things with universal motors will have their commutators sparking considerably more as the frequency decreases. Current will go up and torque down as you leave the operating area. Light bulbs don't care and are probably the safest thing to try. Incandescent lamps will flicker a lot less noticeably at the same frequency as LED. These will also work over a wider frequency range.

You can also try music. Electronic music or those bass CDs will work surprisingly well as most of the fundamentals are in the 60Hz range. I do remember a demonstration back in the 90s with a guy playing Techmaster PEB in a car with a large amp (HiFonics Colossus) bridged connected to an extension cord with a porter cable circular saw. He was able to cut 2x4's just as easy as plugged into the wall and you could hear the saw surging up and down to the beat of the bass! It was actually quite funny.

 

[Mark R]

Those elements seemed to glow a little brighter when hooked to DC but what your saying makes sense since I have a 1500W space heater that uses 13 amps at full power..

That's because the DC voltage is higher - it's 280-290V not 220V as indicated. The guy made a mistake in the labelling.

Still, the point is made.

Rectified and capacitor smoothed DC gains the peak voltage of the incoming AC - which is Sqrt(2) * Vac. - So 220V AC, when rectified and smoothed is approx 290 V DC.

 

[NL5]

Wow. So much good information, and so much more dis-information.

edit -

One big area off misinformation. AC motors run WAY more efficiently of of DC. Look up DC Pulse Width Modulation. VFD's are getting cheaper by the day. I can't think of the last AC motor I installed that wasn't controlled by a VFD.

 

[fatpat268]

What I've always wanted was a standardized external switching PSU that I could connect multiple appliances to. For example, my TV with all the classic video game consoles connected to it uses a ton of outlets and the efficiency losses from each having a different power transformer multiply. The Sega Genesis with all the accessories alone uses three bricks and a plug (console, Sega CD, Sega 32X, TV). One high-capacity "brick" plugged into the AC source with DC wires to each device would be far more efficient.

Check this out:
http://www.retrogamecave.com/sega-ac_adapter.html

Currently sold out, but something like that does infact exist.

 

[BUTCH1]

Try 400Hz for size.

Imagine having 25Hz power.

Does anyone remember those party bulbs from the 70s? They have a big, lazy filament and in the middle post there was a small alnico bar magnet attached. The AC frequency would act on this field causing the filament to wiggle back and forth like a tubifex worm under stress. They were available in different colors too. Today we just have boring LED bulbs that change color. At least they last longer.

As far as frequency you can try this experiment. If you have a computer you have a function generator. Just connect your sound card to a suitable amplifier and you're all set. Receivers and home audio gear are OK but a PA amp is usually better suited as it has more power and is more robust.

Connect the output terminals to an appliance. It needs to be on the small side for a home receiver in the 100WPC range for sure, whereas QSC PowerLight, Crown I-Tech, etc. will power larger devices like power tools, vacuum cleaners, etc.

Do be advised that this has the potential to destroy just about everything if something goes wrong, but that's what makes these kinds of things fun, right?

If you start with a 60Hz sine wave your device will run normally. Of course the amplifier will need to have sufficient voltage (120V) on its output terminals and most receivers won't do this. However that does not mean it won't work. Power drills, small vacuum cleaners, sewing machines, etc. have universal motors that will work with far less voltage. Try different waveforms such as square wave, triangle, sawtooth, etc. to see how it affects the run and start performance.

Finally try different frequencies. Most universal motors will run quite a ways outside of 50/60Hz of their nameplate but do remember things with universal motors will have their commutators sparking considerably more as the frequency decreases. Current will go up and torque down as you leave the operating area. Light bulbs don't care and are probably the safest thing to try. Incandescent lamps will flicker a lot less noticeably at the same frequency as LED. These will also work over a wider frequency range.

You can also try music. Electronic music or those bass CDs will work surprisingly well as most of the fundamentals are in the 60Hz range. I do remember a demonstration back in the 90s with a guy playing Techmaster PEB in a car with a large amp (HiFonics Colossus) bridged connected to an extension cord with a porter cable circular saw. He was able to cut 2x4's just as easy as plugged into the wall and you could hear the saw surging up and down to the beat of the bass! It was actually quite funny.

We just got brand new electric Toyota forklifts at work last Feb., weird thing is the motors on these run on AC despite the battery is a monster 36V DC, it actually takes that and converts it to AC for the motors, I can tell when I'm working the shit out of it (lifting 55gl drums) for about 2-3 hours it has that "smell", of hot semiconductors and it's cooling fans go to max RPM to draw air through the body to cool things down..

 

[Mark R]

We just got brand new electric Toyota forklifts at work last Feb., weird thing is the motors on these run on AC despite the battery is a monster 36V DC, it actually takes that and converts it to AC for the motors, I can tell when I'm working the shit out of it (lifting 55gl drums) for about 2-3 hours it has that "smell", of hot semiconductors and it's cooling fans go to max RPM to draw air through the body to cool things down..

That's the way it's going today.

If you think about it, ALL motors run on AC. DC motors MUST have some form of inverter in them.

In classic DC motors (and universal motors), the brushes and commutator serve as a crude mechanical inverter, reversing the direction of current flow through the rotor windings as the rotor turns.

In the case of brushless DC motors (like a CPU fan), there is a permanent magnet rotor, and a crude inverter is made from a couple of transistors and a magnetic field sensor that detects the position of the rotor.

Going for a brushless design reduces friction, improves efficiency, reduces noise and improves reliability. If you're using an electornically speed controlled DC motor, it's only a slight upgrade to the semiconductors to go to a full 3-phase AC induction motor.