Global Warming?

[Rob-D]

Absolutely, but you will never see everyone generating their own power so AC is here to stay. Step up/ step down is too efficient for DC to compete for transmission. Distance losses will always be a killer with DC.
larry

Larry,
That's what I'm saying, there will be a time when the long range grid is no longer viable.

Today DC Step up/step down DC beats AC transformer efficiencies without the size or the massive amounts of copper. Most electronic gear runs on low voltage DC, why rectify 120 VAC to get 6VDC when you can run a simple high efficiency circuit to get the same thing? My DC inverters run over 95%efficiency. You just can't beat a MOSFET with an RDSon in the micro-ohms switching at a couple of Mhz, now you get a wall transformer with a 99% efficiency, not transformers, no heat and it's the size of your thumb.

If local communities generate their own power, not only will there be short grid runs but things like grid terrorism will no longer be an issue. I think by then most people will be autonomous and people like me won't be the exception but the norm.

Rob

 

[Rob-D]

Really, what parts failed?

GE Fanuc Distributor Series 90-70 PLC IC697CPX935 IC697CPX782

The GE Fanuc Series 90-70 was introduced in 1988 as a full functioning PLC system. It utilized the IC697CPU782 processor which soon became the IC697CPX782 CPU. The new processors no longer needs the IC697MEM715, IC697MEM719, IC697MEM731, IC697MEM733 or IC697MEM735 memory modules. The new IC697CMM742 Ethernet controller eliminates the older IC697CMM741.

I never worked on the machines specifically but I know those old servo boards weren't as good as the new stuff.

Still using your 1988 computer?

Do you ever ask a question without trying to bait people? I thought we went through this. If I stop answering your questions don't wonder why.

Rob

 

[Rob-D]

What do you think will last longer, an MP3 with no moving parts or your old cassette deck? Even the famous Nakamichi Dragon couldn't last like the cheapest MP3 player. We were always changing heads on reel to reel decks too.

Isn't there a difference on how the music may be recorded which may relate to quality of sound?

There's a lot of controversy on this. I agree with some and some I think is hype. I do think tubes sound better than solid state amps.... to a degree, but for power amplification I prefer SS over tubes. For line stages I prefer tubes. I think a hybrid amp is better design. I haven't heard the class 'D' and class 'T' power amps enough to comment on them, I do know that I like the sound of class 'A' amps over 'AB' though and single ended low power tube amps have a real charm.

Signal processing is another story. There's no question that digital has won hands down in areas like communication and video but digital audio is not as clear cut an issue. While I do think it's better in certain ways there is a strong argument for vinyl which is coming back. How you amplify low current moving coil cartridges on the other hand is, in my view, better accomplished with low noise JFETs, you can use tubes but the noise floor can be a problem.

The problem is criteria, there are no parameters for musicality, that is, distortion figures don't mean a lot but we keep using them. No one can hear the difference between .01 and 0.0005% distortion but we keep listing distortion in specs because people think it matters. (Actually we like certain distortions, some second harmonics and such from tubes)
I think slew rate is a much more important figure and my designs run high slew rates, some over 1000 V/us and I can hear the difference, so can others who don't know the technology but just say," this amps sound better, it sounds 'clearer'".

Simaudio, Creek and a few others who list it in their specs. must think it's important too.





Rob

 

[Rob-D]

DC has several disadvantages making it impractical for short distances.
1.) the cost of the equipment "transforming" the voltage (inverters) is expensive relative to energy saving.
2.) It is unidirectional. It can be made bidirectional but it would become even more to expense.

For long distances like for across the country where lower losses are worth the expense DC is hard to beat. In fact that is only system (beside some exotic) making cross country possible and practical.

DC is fine for short distances, buck/boost circuits have resolved that and quite inexpensively, that's why all the new solar stuff is so great. My PV runs MPPTs on each panel. We could never have gotten that kind of efficiency 10 years ago.
Even variable frequency circuits are now common. Years ago it was a real chore to get a pure sine inverter, everything was "modified sine" which is basically a square wave. Those square wave units ran all the AC motors hot. It's not hard to understand why, you're pumping a 60Hz square wave into a low impedance coil, that has to heat things up!
I don't know, are mod sine inverters still selling? Maybe in the cha-cha units used in car cigarette lighters?

Rob

 

[Rob-D]

I thought that Tesla and Edison resolved the issue over high voltage AC vs DC over 100 years ago. I know that new technologies and conductors could change the equation, I just haven't read anything about it lately. I could see where DC would have some advantages and technologically, changing the voltage shouldn't be insurmountable using inverters and transformers. However, It would be impractical to convert all household appliances and industrial applications to DC.

Jim

They did, Westinghouse won out but we didn't have the technology AND lack of resources we have today.

You have to remember, before the advent of the AC motor (Tesla) industry was plagued by steam generation explosions or building plants near natural energy sources like rivers an water falls. The AC motor meant that industry could put plants wherever they wanted relatively inexpensively. The AC motor let you have a steel manufacturer next to the auto plant that utilized the steel.

Yes, that's what I'm saying, today technology has changed the equation, today we can do just about anything we want to a signal or power source. Now you get an IGBT ( isolated gate bipolar transistor) switching high voltages with ease.

Rob

 

[SPYDERLK]

HVDC (high Voltage DC) long distance transmissions are significantly more efficient and even cheaper than long distance AC transmission. AC long distance lines suffer skin effect when the current is located on the surface of the conductor, they require three conductors. They have inductive and capacitive leakage against adjacent conductors and ground.

In comparison to DC - Yes. ... But for 60Hz; in comparison to much - not much. I also expect that ~ million Volt DC lines and dealing with voltage conversions would be a bigger deal.
larry

 

[SPYDERLK]

DC is fine for short distances, buck/boost circuits have resolved that and quite inexpensively, that's why all the new solar stuff is so great. My PV runs MPPTs on each panel. We could never have gotten that kind of efficiency 10 years ago.
Even variable frequency circuits are now common. Years ago it was a real chore to get a pure sine inverter, everything was "modified sine" which is basically a square wave. Those square wave units ran all the AC motors hot. It's not hard to understand why, you're pumping a 60Hz square wave into a low impedance coil, that has to heat things up!
I don't know, are mod sine inverters still selling? Maybe in the cha-cha units used in car cigarette lighters?

Rob

Rob, do you know of a supplier for a 24 or preferably 36 VDC to 240 AC ~2+KW pure sine inverter? I want to run my distant well on site from our golf cart in a pinch.
larry

 

[Rob-D]

In comparison to DC - Yes. ... But for 60Hz; in comparison to much - not much. I also expect that ~ million Volt DC lines and dealing with voltage conversions would be a bigger deal.
larry

When you get to that level, I agree. Transformer AC is a better option but I'm not a fan of long distance grid power.

Also the skin affect is the inverse of wire diameter: F=124/d^2, until you start working with relatively high frequencies it's not doing much as far as impedance goes.

Once you get to local communities generating their own power, which by the way is starting to happem, 1MV is a not an issue. So we start slowly, right now small communities can supplimentthe grid, tomorrow theyare the grid.

Infrastructure is a bear, that's why we don't have electric cars running over ICE cars. Imagine if we had stayed with electrics and had an infrasrructure built around that technology and you pulled into a stop and all of a sudden we decided to go to petro. There would be no grid for it and no one would want gas cars.

Rob

 

[Rob-D]

This is exactly what I'm talking about.

Pretty much 'Plug and play'.

SpinRay DeckPower120 Solar Scituate,RI

$1100.00 at Amazon and you get a 30% credit from the gov. Buy more panels and just add them on as you need them.

Oil keeps going up, great! The more it goes up and the more PV drops the less oil will be a viable solution for the country.

Rob

 

[Jim Thompson]

When you get to that level, I agree. Transformer AC is a better option but I'm not a fan of long distance grid power.

Also the skin affect is the inverse of wire diameter: F=124/d^2, until you start working with relatively high frequencies it's not doing much as far as impedance goes.

Once you get to local communities generating their own power, which by the way is starting to happem, 1MV is a not an issue. So we start slowly, right now small communities can supplimentthe grid, tomorrow theyare the grid.

Infrastructure is a bear, that's why we don't have electric cars running over ICE cars. Imagine if we had stayed with electrics and had an infrasrructure built around that technology and you pulled into a stop and all of a sudden we decided to go to petro. There would be no grid for it and no one would want gas cars.

Rob

Until 1913 when the electric starter was introduced, electric cars out numbered gas powered and I think by a significant margin.

Jim