A More Efficient Bridge Rectifier?

There's already a DC interconnect running the length of California. From The Dalles, Oregon down to LA. +/- 500kV overhead. Some of the power it carries comes from as far as Grand Coulee.

That's what we have pumped-storage hydro schemes for.

SNIP

Electrical 101.

Distrubution of DC is will generatae higher losses. I SQUARED * R.

Is it capable of transmitting power in both direction ? As far as I understand this is the old style point-to-point SCR system, in which you had to reverse the line polarity, in order to transfer power in the opposite direction.

To support wind power, there must be several power sources and the ability to continuously switch the power transfer direction.

Pumped storage systems are really stupid due to the low total system efficiency (pump+turbine).

An ordinary hydroelectric plant in a river with a sufficient reservoir capacity should be more efficient. Close the hydroelectric plant during the day when solar power is available. At night, run the water accumulated in the reservoir through the turbines. In order to minimize the environmental impact, the reservoir should have sufficient area, in order to avoid problems with large water level changes.

I think you skipped a lecture in E101 or something. ;-)

Sinusoidal power and a resistive load gives the same RMS current and same power for the same resistance, so the I^2*R losses are exactly the same, all other things being equal.

But there are AC losses from induced eddy currents and capacitive loading that occur ONLY with AC. Converting AC to DC for switching supplies for electronics and motor controllers either requires complex and expensive power factor correction circitry or draws current that increases I^2*R losses. The conversion itself eats a bit of power (in the bridge rectifier, for example).

Also, the filter capacitors required for SMPSs are bulky and have relatively short lives. (OTOH, we can make doublers easily with AC input).

But if, say, 300 VDC was available world-wide out of the wall, we could all have notebook computers that didn't require those stupid brick things. That would be good.

Best regards, Spehro Pefhany

Facts are facts. You *are* a leftist loser and go out of your way to prove it every day.

KRW: If you would learn to SHUN MooseFET, Slowman, and AlwaysWrong and his nyms, you could lower your blood pressure significantly ;-)

Isn't it also so that only an idiot would debate another idiot ?:-) ...Jim Thompson

At the same voltage (DC or RMS), losses will be the same.

-- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)

... and then it gets cold, uncle Leroy plugs in the old space heater, the one that didn't have a safety thermodisk yet ... phsss ... *PHUT* ... li'l meltdown on the carpet but uncle Leroy has dozed off by now ... smoke alarms blare ... sirens start wailing at the engine company 17 ...

Opps Your right.

I'll try and redeem myself.

The reason DC transmission is seldom used is because of DC transmission losses. For example how would you get 300Vdc to every residence say at +/- 20%? The DC losses in the transmission line make that difficult and costly to implement on a wide scale.

Whereas with AC start out at a large voltage and with a relatively small current reduces the DC losses and just use a transformer to service a section of residence.

Hopefully I didn't stick my foot any further down my throat.

I guess I should be thankful you caught it and not Phil :-) He wouldnt be so civil.

There Joerg goes again *PHUT* *PHUT* *PHUT* *PHUT* *PHUT* *PHUT*

Whew! Sure glad I don't live next door ;-) ...Jim Thompson

DC is primarily used only for long distance UHV distribution.

... Except in some old parts of New York City ;-) ...Jim Thompson

Well, the good news is that the next fire hydrant is across from our driveway :-)

Same here, actually, straight across the street. ...Jim Thompson

Both wind and solar need some sort of storage, especially if and when they become a major source of electric power. There are some economies of scale by building large centralized wind farms and solar facilities in areas where these natural resources are plentiful. But I think we will see an increase in the number of individual, commercial, and industrial private on-site generation, which will distribute the power sources and minimize the cost of transmission.

Such sites will also have their own storage facilities, which may take various forms. And as electric vehicles become more prevalent, they will provide a distributed means of storage especially during low-peak times, as they will be charging overnight. A flatter demand curve with high storage capacity reduces the overall load on transmission lines and allows conventional power plants to operate continually at a reduced and optimal level.

A strong commitment to such a scenario will have the effect of creating many new jobs and stimulating the economy, at the same time it reduces the negative environmental (and economic) impact of burning fossil fuels or increased proliferation of nuclear energy.

Paul

Of course, DC mains will have their own unique standards for plugs and sockets, and devices made for 300VDC will have their own safety requirements. Even if someone splices a pigtail on an old 120 VAC heater and plugs it into 300 VDC, it will likely pop the main breaker before it melts down. A greater danger would be that the squirrel cage fan would burn up, and anyone with half a nose or an eye would smell it and see smoke and pull the plug within seconds. If uncle Leroy ignores the obvious signs of the heater self-destructing, and dozes off within the few seconds that it would take to become obvious, then poor drugged up and drunken uncle Leroy has just been eliminated from the gene pool by Darwinian selection.

Paul

Not too bad. The technology exists today to replace our infrastructure with DC -- same voltages for transmission efficiency reasons, just use DC transformers (i.e. converters). Nice part is each 'transformer' can be regulating and current protected, electronically.

The advantage over the current system would be slight, while retooling the world as we know it (putting a VFD in front of every motor) would cost trillions, which is why nobody's doing it, of course.

Tim

If electric power becomes much more expensive, then the efficiency advantages are magnified to the point where they may become worthwhile. Much of the infrastructure is in need of upgrade anyway, and conversion can be done on a gradual and piecemeal basis. When 300VDC is brought into a residence, it would not be too costly to install a PWM VF motor controller that could provide 3 phase power at 60 Hz for the entire house. 220 VAC appliances usually run fine on 208 VAC. The electrical power for a typical house is about 20 kW or 15 HP, which is a moderate size controller. Ideally, the house would be rewired for 300 VDC, which could be done using the same wiring and different sockets. One or two circuits could be left as

It would also have the advantage of a fairly simple battery backup system for power outages. A bank of 25 automotive type batteries could supply

The inception of a changeover such as this would provide thousands of skilled and semi-skilled jobs and also provide an impetus for technological innovation. Eventually it may cost trillions, but that is money that stays in the country and fosters improvement of local economies.

Any downsides?

Paul

"Paul E. Schoen" wrote in news:7x%dn.77625$s%. snipped-for-privacy@newsfe18.iad:

except then you need LOTS of individual power storage battery sets and DC- AC converters,and the required maintenance of them,greatly expanding your costs and lowering your efficiency. (and piss off your neighbors with the prop noise and bird kills.)

Face it,wind power is not economically PRACTICAL.

Yeah,in other countries. From what I've read,nations other than the US are the ones making the wind turbines and having those jobs. The US seems to be getting out of manufacturing,and losing all those good paying jobs.(and not gaining anything for it)

you can "commit" all you want,but don't try to mandate that others "commit" too.Or that we "subsidize" it.(because it's not economically practical without subsidies)

IOW,stop screwing around and build clean,reliable nuclear power plants that supply power around the clock,for many years. Along with good paying jobs.

I'd say that's filed on under costly and difficult to implement. Are you suggesting that all current pole transformers be replaced with SMPS's like a buck or sepic?