Also these electronic gizmos would continue to work during power outages.

http://www.electricgeneratorsdirect.com/

On Sat, 3 Oct 2009 04:35:59 -0700, "Bill"
wrote:

THIS DOES'NT MAKE MUCH SENSE
IT IS DOABLE BUT WHY ?


In my case, basically for higher reliability of some electronic gizmos. Also
to have pretty much maintenance free electronic gizmos so far as battery
replacement goes.

I live in a rural area and the electricity goes out at least twice a
month...

And I've had problems with phone answering machines which need to have the
time reset each time the power goes out. Or other models the batteries wear
out quickly during a power outage. So my phone answering machine needs
constant attention!

http://www.electricgeneratorsdirect.com/

Then I have about 7 battery operated clocks (due to power outages), 6
battery electronic thermometers for temperature monitoring because I have a
wood stove and want to keep an eye on the temperatures when I am in other
rooms of the house, then about 6 battery smoke detectors / CO detectors
everywhere (again for wood stove monitoring).

Basically I frequently need to replace a battery in something. It would be
nice to have just one central battery and not worry about it except once
every several years!

One central battery means one total failure

http://www.thomasdistributing.com/

On Sun, 04 Oct 2009 12:44:44 -0700, James Sweet
wrote:



Remember, it's just a discussion
about possibilities. Good grief, 78xx regulators are very
inexpensive and DC-DC controllers are getting that way too.

They're *very* wasteful too. I don't want my power bills to go up 7x.



In all fairness, DC-DC converters can exceed 95% efficiency, and 85% is
common. They're really not too bad.

78xx switch mode DC-DC.

95% efficiency is a bit optimistic for the real world. 85%, perhaps.
I still don't want to increase my power bill by even 10%, though it's
better than 10x.

Most power supplies are more or less the same thing. That said, there
is still no advantage to DC distribution and a *LOT* of
disadvantages.

The class II transformers used to power most small stuff are down around
50%. It's one reason switchmode power supplies have become popular for
those applications. A SMPS is nothing but a DC-DC converter that first
rectifies the AC line to DC.

You still haven't identified *ONE* reason to go through this crap.

Andy wrote:
On Oct 3, 5:35 am, "Bill" wrote:
THIS DOES'NT MAKE MUCH SENSE
IT IS DOABLE BUT WHY ?
In my case, basically for higher reliability of some electronic gizmos. Also
to have pretty much maintenance free electronic gizmos so far as battery
replacement goes.

I live in a rural area and the electricity goes out at least twice a
month...

And I've had problems with phone answering machines which need to have the
time reset each time the power goes out. Or other models the batteries wear
out quickly during a power outage. So my phone answering machine needs
constant attention!

Then I have about 7 battery operated clocks (due to power outages), 6
battery electronic thermometers for temperature monitoring because I have a
wood stove and want to keep an eye on the temperatures when I am in other
rooms of the house, then about 6 battery smoke detectors / CO detectors
everywhere (again for wood stove monitoring).

Basically I frequently need to replace a battery in something. It would be
nice to have just one central battery and not worry about it except once
every several years!

Many items in the home can run off of DC; some can't. The big problem
with DC systems is excessive current draw and the corresponding
voltage drop. In order to use existing house wiring (12 and 14 ga),
the DC voltage would have to be much higher than 48V. At 48 volts the
current draw for any AC device would be more than double. Watts =
volts times amps. If your toaster draws 1000W and your voltage supply
s 48VDC, then you need over 20 amps to run the toaster. Standard
outlets are rated for 15A. Then theres the problem of motors (fans,
heater blower, refrigerator compressor, jacuzzi pump, etc). An AC
motor can not work on DC. However, many motors in the home are what
are called "universal" motors. These motors work for AC and DC. Most
power tools and small kitchen appliances use universal motors. For
example, a coffee grinder will run on DC, although it needs about
40-50V to get started.

And yet there is another problem of electric generation, and that's
another can of worms altogether. 100 years ago this country struggled
over the AC/DC concept for the electrical grid. Edison was a
proponent of the DC system, and Westinghouse was a proponent of the AC
system. There's a great book called "The Empires of Light" which
describes the technological and political wars related to this
struggle.

Having said all this, if I lived in a rural area, far from services, I
would have a DC battery storage system in my house/garage.

AG

At last someone who gets it. There have been others critical of
a separate DC power system and they have good point about why
you should not reinvent the wheel. Inverter technology has come
a long way in recent years and what would you think of a central
high capacity inverter coming off your battery bank. Many of the
backup generator systems I've installed over the years have not
been designed to take care of the whole electrical load of a
home or business but to supply power to the essentials through
a transfer switch and sub-panel. The same thing can be done with
an inverter system. By the way, Tesla is more of a hero to me
than Edison. I think Edison just had a better publicity machine.

TDD

On Sun, 04 Oct 2009 15:06:45 -0500, The Daring Dufas
wrote:

krw wrote:
On Sun, 04 Oct 2009 03:51:51 -0500, The Daring Dufas
wrote:

krw wrote:
On Sat, 03 Oct 2009 16:51:51 -0500, The Daring Dufas
wrote:

krw wrote:
On Sat, 03 Oct 2009 00:22:41 -0500, The Daring Dufas
wrote:

Bill wrote:
How about getting rid of all those batteries in various devices in the home
and connecting the battery connections to one central battery?

That is to run separate wires when wiring a home and these would carry say
12 volts DC. There would be a central large battery and battery charger like
the type used in a computer UPS.

Then at each electronic gizmo which needs a battery, use a "battery
eliminator" along with a voltage regulator to supply it with the correct
voltage. And plug this into a nearby 12 volts DC "outlet".

This could provide battery power to smoke detectors, carbon monoxide
detectors, HVAC thermostat, security system, clocks, digital thermometers,
computer UPS, phone answering machine, etc.

Then only ONE battery to worry about...

A 9 volt battery eliminator picture...
http://www.wirelessmicrocolorcam.com... 7a77410624ea


My suggestion would be for a 48 volt DC system.
Think "transformer".

Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC.
The maximum "safe" voltage. There is a reason power transmission is
in the hundreds of KV. AC.

The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages.
You really want to waste power, don't you?

The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
Not everyone wants to waste ten times the power they use.
Do you have the slightest clue of what the discussion
is about? It's a hypothetical discussion about a DC power
distribution system for a home.

DO you have the *slightest* clue about electronics? No, I didn't
think so. To answer your question, yes, I can read and understand
your post quite well. ...well enough to know you're clueless.

I neither seek to impose
a standard or ridicule the ideas of others.
Think before posting in an electrical engineering (science) group.

I do have about
four decades of experience with all things electrical and
electronic but sadly, I don't know everything. I wish I did.
You clearly haven't and don't.

The short story is that linear regulators waste tremendous power,
particularly in this application (large voltage drops), making your
idea worthy of ridicule.

There is a very good reason AC is used to transmit power. Thinking
that your brainchild throws out a hundred years of practice is another
reason it's worthy of ridicule.

Well professor, I would only use the damn things for low
power applications.

So you're going to add another level of wiring into homes. Real
smart.

For any kind of load, a DC-DC converter
would be the way to go.

Why not stay with the AC distribution we have and use a small power
supply for those things that need low power. Oh, that's what we are
doing.

Remember, it's just a discussion
about possibilities. Good grief, 78xx regulators are very
inexpensive and DC-DC controllers are getting that way too.

They're *very* wasteful too. I don't want my power bills to go up 7x.

Ridicule bothers me not because as a small boy I had Irish
nuns for teachers. That's also why I have no fear of terrorists.
I'll take Tesla's power distribution system over Edison's any
day. Darn, now I'm gonna have to go out in the back yard and
try to build one of those power transmitting towers that
Nikola used to play around with. Do you scream at your TV
too?

IOW, you're simply stupid as a stone.

You still don't get it, it's only an exercise in what's
possible.

No, Dufus, it is you who doesn't "get it". What is possible is
irrelevant, if the dream is worse than what is.

Look at all the replies on how and why this or
that won't work.

Yes, all telling you that your idea is stupid.

That's what a discussion is all about.

I agree. Everyone agrees that your idea is stupid.

Good grief, you've no idea what the term "thought provoking"
means.

You have to have some thoughts before they can be provoking. Try it.

You get your pointy little head tweaked and result
to name calling?

You are what you are. I've simply told you what you are. Grow up and
deal with it.

You point out what's wrong with an idea
and that's a good thing.

Something that should be immediately obvious to anyone posting in a
science/engineering group.

When I ran a crew on a project,
I would deliberately tell them to do something that was
wrong. After having to stop them a few times, the really
smart ones caught on and challenged me. I told them that if
they even had a feeling something was wrong, speak up but
be prepared to explain why. A crew like that can save a
company a lot of money. I once installed a Halon fire
suppression system in a mission control center and the
prints I was given made no sense to me. I argued with the
HMFIC and was told it's on the print, DO IT. The prints
had been prepared by my employer not The Core of Engineers.
The cost of a mistake like that falls on those who supply
the prints. When the manufacturer's rep arrived, he exclaimed,
"These prints are wrong! It's a good thing you didn't go by
this!". Even though I saved the company a great deal of
money, it put a bug up the tailpipe of the HMFIC. Something
about loss of face. Being an agent provocateur is a lot of

Ah, so you're testing us? You're not just stupid, but a stupid liar.

fun, keep those ideas coming.

Do keep the really stupid ones to yourself.

krw wrote:
On Sun, 04 Oct 2009 15:06:45 -0500, The Daring Dufas
wrote:

krw wrote:
On Sun, 04 Oct 2009 03:51:51 -0500, The Daring Dufas
wrote:

krw wrote:
On Sat, 03 Oct 2009 16:51:51 -0500, The Daring Dufas
wrote:

krw wrote:
On Sat, 03 Oct 2009 00:22:41 -0500, The Daring Dufas
wrote:

Bill wrote:
How about getting rid of all those batteries in various devices in the home
and connecting the battery connections to one central battery?

That is to run separate wires when wiring a home and these would carry say
12 volts DC. There would be a central large battery and battery charger like
the type used in a computer UPS.

Then at each electronic gizmo which needs a battery, use a "battery
eliminator" along with a voltage regulator to supply it with the correct
voltage. And plug this into a nearby 12 volts DC "outlet".

This could provide battery power to smoke detectors, carbon monoxide
detectors, HVAC thermostat, security system, clocks, digital thermometers,
computer UPS, phone answering machine, etc.

Then only ONE battery to worry about...

A 9 volt battery eliminator picture...
http://www.wirelessmicrocolorcam.com... 7a77410624ea


My suggestion would be for a 48 volt DC system.
Think "transformer".

Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC.
The maximum "safe" voltage. There is a reason power transmission is
in the hundreds of KV. AC.

The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages.
You really want to waste power, don't you?

The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
Not everyone wants to waste ten times the power they use.
Do you have the slightest clue of what the discussion
is about? It's a hypothetical discussion about a DC power
distribution system for a home.

DO you have the *slightest* clue about electronics? No, I didn't
think so. To answer your question, yes, I can read and understand
your post quite well. ...well enough to know you're clueless.

I neither seek to impose
a standard or ridicule the ideas of others.
Think before posting in an electrical engineering (science) group.

I do have about
four decades of experience with all things electrical and
electronic but sadly, I don't know everything. I wish I did.
You clearly haven't and don't.

The short story is that linear regulators waste tremendous power,
particularly in this application (large voltage drops), making your
idea worthy of ridicule.

There is a very good reason AC is used to transmit power. Thinking
that your brainchild throws out a hundred years of practice is another
reason it's worthy of ridicule.

Well professor, I would only use the damn things for low
power applications.
So you're going to add another level of wiring into homes. Real
smart.

For any kind of load, a DC-DC converter
would be the way to go.
Why not stay with the AC distribution we have and use a small power
supply for those things that need low power. Oh, that's what we are
doing.

Remember, it's just a discussion
about possibilities. Good grief, 78xx regulators are very
inexpensive and DC-DC controllers are getting that way too.
They're *very* wasteful too. I don't want my power bills to go up 7x.

Ridicule bothers me not because as a small boy I had Irish
nuns for teachers. That's also why I have no fear of terrorists.
I'll take Tesla's power distribution system over Edison's any
day. Darn, now I'm gonna have to go out in the back yard and
try to build one of those power transmitting towers that
Nikola used to play around with. Do you scream at your TV
too?
IOW, you're simply stupid as a stone.
You still don't get it, it's only an exercise in what's
possible.

No, Dufus, it is you who doesn't "get it". What is possible is
irrelevant, if the dream is worse than what is.

Look at all the replies on how and why this or
that won't work.

Yes, all telling you that your idea is stupid.

That's what a discussion is all about.

I agree. Everyone agrees that your idea is stupid.

Good grief, you've no idea what the term "thought provoking"
means.

You have to have some thoughts before they can be provoking. Try it.

You get your pointy little head tweaked and result
to name calling?

You are what you are. I've simply told you what you are. Grow up and
deal with it.

You point out what's wrong with an idea
and that's a good thing.

Something that should be immediately obvious to anyone posting in a
science/engineering group.

When I ran a crew on a project,
I would deliberately tell them to do something that was
wrong. After having to stop them a few times, the really
smart ones caught on and challenged me. I told them that if
they even had a feeling something was wrong, speak up but
be prepared to explain why. A crew like that can save a
company a lot of money. I once installed a Halon fire
suppression system in a mission control center and the
prints I was given made no sense to me. I argued with the
HMFIC and was told it's on the print, DO IT. The prints
had been prepared by my employer not The Core of Engineers.
The cost of a mistake like that falls on those who supply
the prints. When the manufacturer's rep arrived, he exclaimed,
"These prints are wrong! It's a good thing you didn't go by
this!". Even though I saved the company a great deal of
money, it put a bug up the tailpipe of the HMFIC. Something
about loss of face. Being an agent provocateur is a lot of

Ah, so you're testing us? You're not just stupid, but a stupid liar.

fun, keep those ideas coming.

Do keep the really stupid ones to yourself.

It wasn't my idea to start with you idiot, it was
a discussion about possibilities. I'm so glad that
a world leading expert such as yourself would chime
in and share your dearth of knowledge. *snicker*

TDD

On Sun, 04 Oct 2009 18:22:56 -0500, The Daring Dufas
wrote:

krw wrote:
On Sun, 04 Oct 2009 15:06:45 -0500, The Daring Dufas
wrote:
snip

When I ran a crew on a project,
I would deliberately tell them to do something that was
wrong. After having to stop them a few times, the really
smart ones caught on and challenged me. I told them that if
they even had a feeling something was wrong, speak up but
be prepared to explain why. A crew like that can save a
company a lot of money. I once installed a Halon fire
suppression system in a mission control center and the
prints I was given made no sense to me. I argued with the
HMFIC and was told it's on the print, DO IT. The prints
had been prepared by my employer not The Core of Engineers.
The cost of a mistake like that falls on those who supply
the prints. When the manufacturer's rep arrived, he exclaimed,
"These prints are wrong! It's a good thing you didn't go by
this!". Even though I saved the company a great deal of
money, it put a bug up the tailpipe of the HMFIC. Something
about loss of face. Being an agent provocateur is a lot of

Ah, so you're testing us? You're not just stupid, but a stupid liar.

fun, keep those ideas coming.

Do keep the really stupid ones to yourself.

It wasn't my idea to start with you idiot, it was
a discussion about possibilities. I'm so glad that

You sure "helped" it along.

a world leading expert such as yourself would chime
in and share your dearth of knowledge. *snicker*

It doesn't take a "world leading expert" to see that you're full of
****. Common sense is enough. Like I said earlier, try thinking for
yourself sometime. Your neuron might be scared at first, but it'll
calm down.

On Oct 4, 5:04*am, The Daring Dufas
wrote:
James Sweet wrote:

My suggestion would be for a 48 volt DC system. Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC. The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages. The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.

TDD

And what would be the advantage? The 78xx series are linear regulators,
they are in effect a regulated resistor that burns up the excess voltage
in the form of heat. On top of that, they max out at 37V input at which
point a substantial heatsink is required to dissipate the heat. The end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.

You could use a switchmode regulator to get decent efficiency, but once
you've gone that route, you may as well just use 120V or 240VAC since
the additional components required are trivial.

Solar and wind power can easily integrate with the existing grid, with
the additional advantage of being able to sell excess capacity back to
the utility. The cost of the special inverter is low compared to what
the panels cost, and dropping all the time. This proposed DC system is
just reinventing the wheel with something inferior to what we already have.

I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.

TDD

DC Power transmission lines are used to rid the line of skin effect
and allow the entire cross section of the conductor to carry current.
They are as yet only practical for long haul point to point
circuits.

--
Tom Horne

Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
James Sweet wrote:

My suggestion would be for a 48 volt DC system. Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC. The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages. The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
TDD
And what would be the advantage? The 78xx series are linear regulators,
they are in effect a regulated resistor that burns up the excess voltage
in the form of heat. On top of that, they max out at 37V input at which
point a substantial heatsink is required to dissipate the heat. The end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.
You could use a switchmode regulator to get decent efficiency, but once
you've gone that route, you may as well just use 120V or 240VAC since
the additional components required are trivial.
Solar and wind power can easily integrate with the existing grid, with
the additional advantage of being able to sell excess capacity back to
the utility. The cost of the special inverter is low compared to what
the panels cost, and dropping all the time. This proposed DC system is
just reinventing the wheel with something inferior to what we already have.
I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.

TDD

DC Power transmission lines are used to rid the line of skin effect
and allow the entire cross section of the conductor to carry current.
They are as yet only practical for long haul point to point
circuits.

--
Tom Horne

That's what I read. My only experience with high voltage power
transmission has been installing buried conduit, setting transformers,
making connections and splices on 15kv coaxial underground cable.
Of course there was all of the other wiring on the low voltage side
of the transformer including the facilities wiring. What I find
fascinating about the long haul high voltage DC power transmission
systems has to do with the changes in technology over the years to
handle the conversion of AC to DC then back again. The early mercury arc
valve systems have got to be a sight to behold. I can imagine a mad
scientist wearing super thick lensed glasses cackling in the background.

TDD

On Mon, 28 Sep 2009 15:24:01 -0700 (PDT), bob haller wrote:

feds should mandate a wall wort standard, the wide variety of them
clogging the landfills is very wasteful. all wall wart devices could
be designed to accept a standard voltage.,....... same for a cell
phone charger standard to cut down on trash

Its finally happened: USB

The Daring Dufas wrote:
Andy wrote:
On Oct 3, 5:35 am, "Bill" wrote:
THIS DOES'NT MAKE MUCH SENSE
IT IS DOABLE BUT WHY ?
In my case, basically for higher reliability of some electronic
gizmos. Also
to have pretty much maintenance free electronic gizmos so far as battery
replacement goes.

I live in a rural area and the electricity goes out at least twice a
month...

And I've had problems with phone answering machines which need to
have the
time reset each time the power goes out. Or other models the
batteries wear
out quickly during a power outage. So my phone answering machine needs
constant attention!

Then I have about 7 battery operated clocks (due to power outages), 6
battery electronic thermometers for temperature monitoring because I
have a
wood stove and want to keep an eye on the temperatures when I am in
other
rooms of the house, then about 6 battery smoke detectors / CO detectors
everywhere (again for wood stove monitoring).

Basically I frequently need to replace a battery in something. It
would be
nice to have just one central battery and not worry about it except once
every several years!

Many items in the home can run off of DC; some can't. The big problem
with DC systems is excessive current draw and the corresponding
voltage drop. In order to use existing house wiring (12 and 14 ga),
the DC voltage would have to be much higher than 48V. At 48 volts the
current draw for any AC device would be more than double. Watts =
volts times amps. If your toaster draws 1000W and your voltage supply
s 48VDC, then you need over 20 amps to run the toaster. Standard
outlets are rated for 15A. Then theres the problem of motors (fans,
heater blower, refrigerator compressor, jacuzzi pump, etc). An AC
motor can not work on DC. However, many motors in the home are what
are called "universal" motors. These motors work for AC and DC. Most
power tools and small kitchen appliances use universal motors. For
example, a coffee grinder will run on DC, although it needs about
40-50V to get started.

And yet there is another problem of electric generation, and that's
another can of worms altogether. 100 years ago this country struggled
over the AC/DC concept for the electrical grid. Edison was a
proponent of the DC system, and Westinghouse was a proponent of the AC
system. There's a great book called "The Empires of Light" which
describes the technological and political wars related to this
struggle.

Having said all this, if I lived in a rural area, far from services, I
would have a DC battery storage system in my house/garage.

AG

At last someone who gets it. There have been others critical of
a separate DC power system and they have good point about why
you should not reinvent the wheel. Inverter technology has come
a long way in recent years and what would you think of a central
high capacity inverter coming off your battery bank.


You just reinvented the wheel. Battery storage with an inverter (or
inverter/charger if a generator is used) to supply normal
voltage/frequency AC is a pretty common method for off grid installations.

Many of the
backup generator systems I've installed over the years have not
been designed to take care of the whole electrical load of a
home or business but to supply power to the essentials through
a transfer switch and sub-panel. The same thing can be done with
an inverter system. By the way, Tesla is more of a hero to me
than Edison. I think Edison just had a better publicity machine.

TDD

On Sep 28, 10:52*am, "Bill" wrote:
How about getting rid of all those batteries in various devices in the home
and connecting the battery connections to one central battery?

That is to run separate wires when wiring a home and these would carry say
12 volts DC. There would be a central large battery and battery charger like
the type used in a computer UPS.

Then at each electronic gizmo which needs a battery, use a "battery
eliminator" along with a voltage regulator to supply it with the correct
voltage. And plug this into a nearby 12 volts DC "outlet".

This could provide battery power to smoke detectors, carbon monoxide
detectors, HVAC thermostat, security system, clocks, digital thermometers,
computer UPS, phone answering machine, etc.

Then only ONE battery to worry about...

A 9 volt battery eliminator picture...http://www.wirelessmicrocolorcam.com....php?pID=47&os...

A more practical solution would be special J boxes that have the
transformers in them and are sensitive to loads being plugged/
unplugged and cut off power to the primary when not in use. Everyone
hates wall warts, they draw a little current even when not in use.
Your electrician would then install these low voltage outlets easily
throughout the house. The important thing is that they be able to
detect "no load" and cut off the primary, and sense an item being
plugged in or turned on and re-connect the transformer primary. Your
whole house DC distribution idea would not be able to do this because
it has to be "ready" globally with no local outlet control sensors.

windcrest wrote:
On Sep 28, 10:52 am, "Bill" wrote:
How about getting rid of all those batteries in various devices in the home
and connecting the battery connections to one central battery?

That is to run separate wires when wiring a home and these would carry say
12 volts DC. There would be a central large battery and battery charger like
the type used in a computer UPS.

Then at each electronic gizmo which needs a battery, use a "battery
eliminator" along with a voltage regulator to supply it with the correct
voltage. And plug this into a nearby 12 volts DC "outlet".

This could provide battery power to smoke detectors, carbon monoxide
detectors, HVAC thermostat, security system, clocks, digital thermometers,
computer UPS, phone answering machine, etc.

Then only ONE battery to worry about...

A 9 volt battery eliminator picture...http://www.wirelessmicrocolorcam.com....php?pID=47&os...

A more practical solution would be special J boxes that have the
transformers in them and are sensitive to loads being plugged/
unplugged and cut off power to the primary when not in use. Everyone
hates wall warts, they draw a little current even when not in use.
Your electrician would then install these low voltage outlets easily
throughout the house. The important thing is that they be able to
detect "no load" and cut off the primary, and sense an item being
plugged in or turned on and re-connect the transformer primary. Your
whole house DC distribution idea would not be able to do this because
it has to be "ready" globally with no local outlet control sensors.


There is no reason that could not be designed into wall-warts.
I've never measured the quiescent primary current draw of old
style wall-warts verses the newer tiny switcher wall-warts, I'm
sure someone has done so. I think your idea is great for office
cubicles because it could be built in during manufacturing and
would help lead to a less cluttered work space, at least for
some people.

TDD

George wrote:
The Daring Dufas wrote:
Andy wrote:
On Oct 3, 5:35 am, "Bill" wrote:
THIS DOES'NT MAKE MUCH SENSE
IT IS DOABLE BUT WHY ?
In my case, basically for higher reliability of some electronic
gizmos. Also
to have pretty much maintenance free electronic gizmos so far as
battery
replacement goes.

I live in a rural area and the electricity goes out at least twice a
month...

And I've had problems with phone answering machines which need to
have the
time reset each time the power goes out. Or other models the
batteries wear
out quickly during a power outage. So my phone answering machine needs
constant attention!

Then I have about 7 battery operated clocks (due to power outages), 6
battery electronic thermometers for temperature monitoring because I
have a
wood stove and want to keep an eye on the temperatures when I am in
other
rooms of the house, then about 6 battery smoke detectors / CO detectors
everywhere (again for wood stove monitoring).

Basically I frequently need to replace a battery in something. It
would be
nice to have just one central battery and not worry about it except
once
every several years!

Many items in the home can run off of DC; some can't. The big problem
with DC systems is excessive current draw and the corresponding
voltage drop. In order to use existing house wiring (12 and 14 ga),
the DC voltage would have to be much higher than 48V. At 48 volts the
current draw for any AC device would be more than double. Watts =
volts times amps. If your toaster draws 1000W and your voltage supply
s 48VDC, then you need over 20 amps to run the toaster. Standard
outlets are rated for 15A. Then theres the problem of motors (fans,
heater blower, refrigerator compressor, jacuzzi pump, etc). An AC
motor can not work on DC. However, many motors in the home are what
are called "universal" motors. These motors work for AC and DC. Most
power tools and small kitchen appliances use universal motors. For
example, a coffee grinder will run on DC, although it needs about
40-50V to get started.

And yet there is another problem of electric generation, and that's
another can of worms altogether. 100 years ago this country struggled
over the AC/DC concept for the electrical grid. Edison was a
proponent of the DC system, and Westinghouse was a proponent of the AC
system. There's a great book called "The Empires of Light" which
describes the technological and political wars related to this
struggle.

Having said all this, if I lived in a rural area, far from services, I
would have a DC battery storage system in my house/garage.

AG

At last someone who gets it. There have been others critical of
a separate DC power system and they have good point about why
you should not reinvent the wheel. Inverter technology has come
a long way in recent years and what would you think of a central
high capacity inverter coming off your battery bank.


You just reinvented the wheel. Battery storage with an inverter (or
inverter/charger if a generator is used) to supply normal
voltage/frequency AC is a pretty common method for off grid installations.


The only systems I've had experience with were in the 5-8kw range
for computer operations in a commercial environment. A big central
UPS with generator backup. If I lived in a rural environment I'm
sure the mad scientist in me would emerge again and I would have
to get involved in something for a home. The only problem is that
I would revert to my childhood on the farm and start looking for
things to blow up.

TDD

On Oct 5, 12:32*pm, The Daring Dufas
wrote:
George wrote:
The Daring Dufas wrote:
Andy wrote:
On Oct 3, 5:35 am, "Bill" wrote:
THIS DOES'NT MAKE *MUCH SENSE
IT IS DOABLE BUT WHY ?
In my case, basically for higher reliability of some electronic
gizmos. Also
to have pretty much maintenance free electronic gizmos so far as
battery
replacement goes.

I live in a rural area and the electricity goes out at least twice a
month...

And I've had problems with phone answering machines which need to
have the
time reset each time the power goes out. Or other models the
batteries wear
out quickly during a power outage. So my phone answering machine needs
constant attention!

Then I have about 7 battery operated clocks (due to power outages), 6
battery electronic thermometers for temperature monitoring because I
have a
wood stove and want to keep an eye on the temperatures when I am in
other
rooms of the house, then about 6 battery smoke detectors / CO detectors
everywhere (again for wood stove monitoring).

Basically I frequently need to replace a battery in something. It
would be
nice to have just one central battery and not worry about it except
once
every several years!

Many items in the home can run off of DC; some can't. *The big problem
with DC systems is excessive current draw and the corresponding
voltage drop. *In order to use existing house wiring (12 and 14 ga),
the DC voltage would have to be much higher than 48V. *At 48 volts the
current draw for any AC device would be more than double. *Watts =
volts times amps. *If your toaster draws 1000W and your voltage supply
s 48VDC, then you need over 20 amps to run the toaster. *Standard
outlets are rated for 15A. *Then theres the problem of motors (fans,
heater blower, refrigerator compressor, jacuzzi pump, etc). *An AC
motor can not work on DC. *However, many motors in the home are what
are called "universal" motors. *These motors work for AC and DC. *Most
power tools and small kitchen appliances use universal motors. *For
example, a coffee grinder will run on DC, although it needs about
40-50V to get started.

And yet there is another problem of electric generation, and that's
another can of worms altogether. *100 years ago this country struggled
over the AC/DC concept for the electrical grid. *Edison was a
proponent of the DC system, and Westinghouse was a proponent of the AC
system. *There's a great book called "The Empires of Light" which
describes the technological and political wars related to this
struggle.

Having said all this, if I lived in a rural area, far from services, I
would have a DC battery storage system in my house/garage.

AG

At last someone who gets it. There have been others critical of
a separate DC power system and they have good point about why
you should not reinvent the wheel. Inverter technology has come
a long way in recent years and what would you think of a central
high capacity inverter coming off your battery bank.

You just reinvented the wheel. Battery storage with an inverter (or
inverter/charger if a generator is used) to supply normal
voltage/frequency AC is a pretty common method for off grid installations.

The only systems I've had experience with were in the 5-8kw range
for computer operations in a commercial environment. A big central
UPS with generator backup. If I lived in a rural environment I'm
sure the mad scientist in me would emerge again and I would have
to get involved in something for a home. The only problem is that
I would revert to my childhood on the farm and start looking for
things to blow up.

TDD- Hide quoted text -

- Show quoted text -

It is a catch 22 situation, you need some current draw for the current
detection sensor. Or you could use a local ni-cad AA battery and have
something that is completey disconnected when the device is unplugged
or turned off, battery charges whenever primary is in connected mode.
Need detection circuit would be powered by the AA ni-cad battery when
the primary is disconnected. Additionally a mechanical switch can be
incorporated to detect when none of the LV outputs physically have a
plug in any jack, then the primary could be switched off. Such a
system would be smart enough to save energy and provide LV power
supplies throughout a home at various voltages. A special J box would
eliminate bulky wall warts that dont fit into power strips, etc.
Manufacturers would supply standardized DC "line cords" and make the
wall wart an optional item when buying a product if your home/office
has DC equipped outlets. I must have at least 8 or 10 wall warts
behind my computer desk right now, they are a PIA.

The centralized system described will be drawing several amp-hours a
day just to keep the storage battery charged and it would have no
local control to actually save transformer idle consumption when
things are switched off or unplugged.

"The Daring Dufas" wrote in message
...
Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
James Sweet wrote:

My suggestion would be for a 48 volt DC system. Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC. The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages. The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
TDD
And what would be the advantage? The 78xx series are linear regulators,
they are in effect a regulated resistor that burns up the excess
voltage
in the form of heat. On top of that, they max out at 37V input at which
point a substantial heatsink is required to dissipate the heat. The end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.
You could use a switchmode regulator to get decent efficiency, but once
you've gone that route, you may as well just use 120V or 240VAC since
the additional components required are trivial.
Solar and wind power can easily integrate with the existing grid, with
the additional advantage of being able to sell excess capacity back to
the utility. The cost of the special inverter is low compared to what
the panels cost, and dropping all the time. This proposed DC system is
just reinventing the wheel with something inferior to what we already
have.
I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.

TDD

DC Power transmission lines are used to rid the line of skin effect
and allow the entire cross section of the conductor to carry current.
They are as yet only practical for long haul point to point
circuits.

--
Tom Horne

That's what I read. My only experience with high voltage power
transmission has been installing buried conduit, setting transformers,
making connections and splices on 15kv coaxial underground cable.
Of course there was all of the other wiring on the low voltage side
of the transformer including the facilities wiring. What I find
fascinating about the long haul high voltage DC power transmission systems
has to do with the changes in technology over the years to handle the
conversion of AC to DC then back again. The early mercury arc
valve systems have got to be a sight to behold. I can imagine a mad
scientist wearing super thick lensed glasses cackling in the background.

TDD
Even a 5Kw 6 phase converter was a sight to see- looked like an octopus
with glowing arms and a bright spot dancing on a dish of mercury.
Seriously the advantages of DC transmission has relatively little to do with
skin effect as conductors are typically ACSR with aluminum on the outside
and steel inside- and, at these voltages are grouped in bundles. The size
of the conductor has more to do with mechanical than electrical properties.
DC transmission at high voltages is economical for long lines where the
reduced cost of the line exceeds the added cost of the terminal equipment.
There are also some other technical advantages . This breakeven point is at
a much shorter distance for underground or underwater cable. DC back to back
terminals are often used where frequency differences (e.g. in Japan with
both 50 and 60 Hz systems) or stability concerns arise. They do have the
disadvantage that reasonable and economic circuit breakers for DC don't
exist and this means that the system is essentially point to point rather
than through an interconnected grid. In addition, conversion from one
voltage level to the next is bloody expensive, awkward and inefficient
compared to the use of AC transformers.
At low voltages, even for relatively short distances, DC is not a viable
option.

--
Don Kelly

cross out to reply

Don Kelly wrote:

"The Daring Dufas" wrote in message
...
Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
James Sweet wrote:

My suggestion would be for a 48 volt DC system. Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC. The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages. The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
TDD
And what would be the advantage? The 78xx series are linear
regulators,
they are in effect a regulated resistor that burns up the excess
voltage
in the form of heat. On top of that, they max out at 37V input at
which
point a substantial heatsink is required to dissipate the heat. The
end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.
You could use a switchmode regulator to get decent efficiency, but
once
you've gone that route, you may as well just use 120V or 240VAC since
the additional components required are trivial.
Solar and wind power can easily integrate with the existing grid, with
the additional advantage of being able to sell excess capacity back to
the utility. The cost of the special inverter is low compared to what
the panels cost, and dropping all the time. This proposed DC system is
just reinventing the wheel with something inferior to what we
already have.
I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.

TDD

DC Power transmission lines are used to rid the line of skin effect
and allow the entire cross section of the conductor to carry current.
They are as yet only practical for long haul point to point
circuits.

--
Tom Horne

That's what I read. My only experience with high voltage power
transmission has been installing buried conduit, setting transformers,
making connections and splices on 15kv coaxial underground cable.
Of course there was all of the other wiring on the low voltage side
of the transformer including the facilities wiring. What I find
fascinating about the long haul high voltage DC power transmission
systems has to do with the changes in technology over the years to
handle the conversion of AC to DC then back again. The early mercury arc
valve systems have got to be a sight to behold. I can imagine a mad
scientist wearing super thick lensed glasses cackling in the background.

TDD
Even a 5Kw 6 phase converter was a sight to see- looked like an octopus
with glowing arms and a bright spot dancing on a dish of mercury.
Seriously the advantages of DC transmission has relatively little to do
with skin effect as conductors are typically ACSR with aluminum on the
outside and steel inside- and, at these voltages are grouped in
bundles. The size of the conductor has more to do with mechanical than
electrical properties.
DC transmission at high voltages is economical for long lines where the
reduced cost of the line exceeds the added cost of the terminal
equipment. There are also some other technical advantages . This
breakeven point is at a much shorter distance for underground or
underwater cable. DC back to back terminals are often used where
frequency differences (e.g. in Japan with both 50 and 60 Hz systems) or
stability concerns arise. They do have the disadvantage that reasonable
and economic circuit breakers for DC don't exist and this means that
the system is essentially point to point rather than through an
interconnected grid. In addition, conversion from one voltage level to
the next is bloody expensive, awkward and inefficient compared to the
use of AC transformers.
At low voltages, even for relatively short distances, DC is not a viable
option.


From my reading, the problem of capacitive reactance is also minimized
with the DC transmission lines. When I was at Kwajalein Missile Range
during the late 80's, I got the chance to explore the old phased array
radar installation on Meck Island. It had a room we called the
Frankenstein room which was the power supply for the old radar. From
what I was told, the way they were able to make that monster scan, was
to change the phase angle of the microwave beam. The Frankenstein room
looked just like a prop from a science fiction movie. I wish I still
had the pictures. Here's a link, look for Meck Island an you can see the
big building in the upper right. There are two pictures, one showing a
view of the missile silo or silos. I don't remember if there were two.

http://www.fas.org/spp/military/facility/kwaj.htm

TDD

On Tue, 6 Oct 2009 17:11:00 -0700, "Don Kelly" wrote:


"The Daring Dufas" wrote in message
...
Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
James Sweet wrote:

My suggestion would be for a 48 volt DC system. Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC. The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages. The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
TDD
And what would be the advantage? The 78xx series are linear regulators,
they are in effect a regulated resistor that burns up the excess
voltage
in the form of heat. On top of that, they max out at 37V input at which
point a substantial heatsink is required to dissipate the heat. The end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.
You could use a switchmode regulator to get decent efficiency, but once
you've gone that route, you may as well just use 120V or 240VAC since
the additional components required are trivial.
Solar and wind power can easily integrate with the existing grid, with
the additional advantage of being able to sell excess capacity back to
the utility. The cost of the special inverter is low compared to what
the panels cost, and dropping all the time. This proposed DC system is
just reinventing the wheel with something inferior to what we already
have.
I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.

TDD

DC Power transmission lines are used to rid the line of skin effect
and allow the entire cross section of the conductor to carry current.
They are as yet only practical for long haul point to point
circuits.

--
Tom Horne

That's what I read. My only experience with high voltage power
transmission has been installing buried conduit, setting transformers,
making connections and splices on 15kv coaxial underground cable.
Of course there was all of the other wiring on the low voltage side
of the transformer including the facilities wiring. What I find
fascinating about the long haul high voltage DC power transmission systems
has to do with the changes in technology over the years to handle the
conversion of AC to DC then back again. The early mercury arc
valve systems have got to be a sight to behold. I can imagine a mad
scientist wearing super thick lensed glasses cackling in the background.

TDD
Even a 5Kw 6 phase converter was a sight to see- looked like an octopus
with glowing arms and a bright spot dancing on a dish of mercury.
Seriously the advantages of DC transmission has relatively little to do with
skin effect as conductors are typically ACSR with aluminum on the outside
and steel inside- and, at these voltages are grouped in bundles. The size
of the conductor has more to do with mechanical than electrical properties.
DC transmission at high voltages is economical for long lines where the
reduced cost of the line exceeds the added cost of the terminal equipment.
There are also some other technical advantages . This breakeven point is at
a much shorter distance for underground or underwater cable. DC back to back
terminals are often used where frequency differences (e.g. in Japan with
both 50 and 60 Hz systems) or stability concerns arise. They do have the
disadvantage that reasonable and economic circuit breakers for DC don't
exist and this means that the system is essentially point to point rather
than through an interconnected grid. In addition, conversion from one
voltage level to the next is bloody expensive, awkward and inefficient
compared to the use of AC transformers.
At low voltages, even for relatively short distances, DC is not a viable
option.


Only the Navy with their ships and submarines make use of DC well. That
still doesn't mean that it wasn't one hell of a costly implementation.

DC is great... on anything miniature, like a scooter, or model
airplane. :-]

Supplying DC feeds that can push as much power as we are used to with
current AC settings in the home would not be easy, and homes are low
consumption examples.

Even if we had compromised, and made AC to the pole, and DC into the
house, the DC part has a lot of pain in the ass required maintenance that
AC does not suffer from. Galvanic effects being the first one I think
of.

OK, so we drop the HV down to about 600V on the local poles, and then
we rectify that and feed the homes? Sounds like a very high
maintainence/service oriented method.

Maybe if we could make a nice DC chopper that would let us step off DC
highs and Gnd lows.. kind of a psuedo-alternation.

On Sun, 04 Oct 2009 22:11:23 -0500, The Daring Dufas wrote:

The early mercury arc
valve systems have got to be a sight to behold. I can imagine a mad
scientist wearing super thick lensed glasses cackling in the background.

Around 2002 I found a wonderful mid-sized mercury arc recifier
in use still for the tram system at the MOTAT museum in Auckland, NZ - it
might still be operational there. Fascinating to watch it run, and the
brightness change according to load as the trams moved around.

I'm sure there are still some running in other countries, too, but that's
the only one I've seen over the years (although various museums have ones
that aren't hooked up - I don't know how many of those are still
technically OK and could be made to run).

There may still be a few tucked away in buildings with really old DC
elevators, although there can't be many left now that haven't been
updated.

cheers

Jules

On Wed, 07 Oct 2009 08:11:30 -0500, Jules
wrote:

There may still be a few tucked away in buildings with really old DC
elevators, although there can't be many left now that haven't been
updated.

cheers

Jules

I do not think there have been DC elevators in the US since the late
Thirties.

On Wed, 07 Oct 2009 16:20:38 -0700, Archimedes' Lever
wrote:

On Wed, 07 Oct 2009 08:11:30 -0500, Jules
wrote:

There may still be a few tucked away in buildings with really old DC
elevators, although there can't be many left now that haven't been
updated.

cheers

Jules

I do not think there have been DC elevators in the US since the late
Thirties.

AlwaysWrong strikes again.

http://science.slashdot.org/article....7/11/16/225213
http://cityroom.blogs.nytimes.com/20...thomas-edison/

"The Daring Dufas" wrote in message
...
Don Kelly wrote:

"The Daring Dufas" wrote in message
...
Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
From my reading, the problem of capacitive reactance is also minimized
with the DC transmission lines.

That too, and that is a major benefit. However, there is still a reactive
problem at the receiving end where it is necessary to have the capacity to
supply reactive. This will be dependent on load and the particular control
of the system as a whole. For long lines this will be less than what would
otherwise be needed to compensate for line capacitance.

--
Don Kelly

cross out to reply

On Oct 8, 11:04*pm, "Don Kelly" wrote:
"The Daring Dufas" wrote in ...

Don Kelly wrote:

"The Daring Dufas" wrote in message
...
Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
From my reading, the problem of capacitive reactance is also minimized
with the DC transmission lines.

That too, and that is a major benefit. However, there is still a reactive
problem at the receiving end where it is necessary to have the capacity to
supply reactive.====== This will be dependent on load and the particular control
of the system as a whole. For long lines this will be less than what would
otherwise be needed to compensate for line capacitance.

--
Don Kelly

cross out to reply

YOU ARE SOUNDING LIKE AN IDIOT

HOW DO YOU SUUPLY REATIVE ?

YOU SHOULD COMMIT HAIKIRI

IT'S CALLED REACTANCE

AND I AM NOT GOING TO SHOW YOU HOW TO ACHIEVE THAT HERE NOR ANYWHERE
ELSE

YOU WILL HAVE TO PAY THE PIPER DONKEY LIKE EVERYONE ELSE

OR JUST SHUT THE FLUX UP

PERMAMNENTLY !

I AM PROTEUS

Proteus IIV wrote:
On Oct 8, 11:04 pm, "Don Kelly" wrote:
"The Daring Dufas" wrote in ...

Don Kelly wrote:
"The Daring Dufas" wrote in message
...
Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
From my reading, the problem of capacitive reactance is also minimized
with the DC transmission lines.
That too, and that is a major benefit. However, there is still a reactive
problem at the receiving end where it is necessary to have the capacity to
supply reactive.====== This will be dependent on load and the particular control
of the system as a whole. For long lines this will be less than what would
otherwise be needed to compensate for line capacitance.

--
Don Kelly

cross out to reply

YOU ARE SOUNDING LIKE AN IDIOT

HOW DO YOU SUUPLY REATIVE ?

YOU SHOULD COMMIT HAIKIRI

IT'S CALLED REACTANCE

AND I AM NOT GOING TO SHOW YOU HOW TO ACHIEVE THAT HERE NOR ANYWHERE
ELSE

YOU WILL HAVE TO PAY THE PIPER DONKEY LIKE EVERYONE ELSE

OR JUST SHUT THE FLUX UP

PERMAMNENTLY !

I AM PROTEUS


Uh, Pro, buddy, there is medication for your problem.
Your county health department may be able to help you
out with a psychiatric referral. FLNF

TDD

The Daring Dufas wrote:
Proteus IIV wrote:

YOU ARE SOUNDING LIKE AN IDIOT

HOW DO YOU SUUPLY REATIVE ?

YOU SHOULD COMMIT HAIKIRI

IT'S CALLED REACTANCE

AND I AM NOT GOING TO SHOW YOU HOW TO ACHIEVE THAT HERE NOR ANYWHERE
ELSE

YOU WILL HAVE TO PAY THE PIPER DONKEY LIKE EVERYONE ELSE

OR JUST SHUT THE FLUX UP

PERMAMNENTLY !

I AM PROTEUS


Uh, Pro, buddy, there is medication for your problem.
Your county health department may be able to help you
out with a psychiatric referral. FLNF

TDD

It is a particularly ignorant troll that infests alt.engineering.electrical.

Just ignore it like everyone else (except one of its equals).

On Oct 6, 7:11*pm, "Don Kelly" wrote:
"The Daring Dufas" wrote in ...



Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
James Sweet wrote:

My suggestion would be for a 48 volt DC system. Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC. The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages. The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
TDD
And what would be the advantage? The 78xx series are linear regulators,
they are in effect a regulated resistor that burns up the excess
voltage
in the form of heat. On top of that, they max out at 37V input at which
point a substantial heatsink is required to dissipate the heat. The end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.
You could use a switchmode regulator to get decent efficiency, but once
you've gone that route, you may as well just use 120V or 240VAC since
the additional components required are trivial.
Solar and wind power can easily integrate with the existing grid, with
the additional advantage of being able to sell excess capacity back to
the utility. The cost of the special inverter is low compared to what
the panels cost, and dropping all the time. This proposed DC system is
just reinventing the wheel with something inferior to what we already
have.
I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.

TDD

DC Power transmission lines are used to rid the line of skin effect
and allow the entire cross section of the conductor to carry current.
They are as yet only practical for long haul point to point
circuits.

--
Tom Horne

That's what I read. My only experience with high voltage power
transmission has been installing buried conduit, setting transformers,
making connections and splices on 15kv coaxial underground cable.
Of course there was all of the other wiring on the low voltage side
of the transformer including the facilities wiring. What I find
fascinating about the long haul high voltage DC power transmission systems
has to do with the changes in technology over the years to handle the
conversion of AC to DC then back again. The early mercury arc
valve systems have got to be a sight to behold. I can imagine a mad
scientist wearing super thick lensed glasses cackling in the background..

TDD

Even a 5Kw 6 phase converter was a sight to see- looked *like an octopus
with glowing arms and a bright spot dancing on a dish of mercury.
Seriously the advantages of DC transmission has relatively little to do with
skin effect as conductors are typically ACSR with aluminum on the outside
and steel inside- and, at these voltages are grouped in bundles. *The size
of the conductor has more to do with mechanical than electrical properties.
DC transmission at high voltages is economical for long lines where the
reduced cost of the line exceeds the added cost of the terminal equipment..
There are also some other technical advantages . This breakeven point is at
a much shorter distance for underground or underwater cable. DC back to back
terminals are often used where frequency differences (e.g. in Japan with
both 50 and 60 Hz systems) or stability concerns arise. They do have the
disadvantage that reasonable and economic circuit breakers for DC don't
exist and this means that *the system is essentially point to point rather
than through an interconnected grid. In addition, conversion from one
voltage level to the next is bloody expensive, awkward and inefficient
compared to the *use of AC transformers.
At low voltages, even for relatively short distances, DC is not a viable
option.

--
Don Kelly

cross out to reply- Hide quoted text -

- Show quoted text -


Thats why Westinghouse beat Edison in the early days of deciding what
electical distribution system to use, Westinghouse (scientist) wanted
AC, Edison (who was more of an inventor than a scientist) would not
let go of his prejudice for DC. I still have an old AC/DC radio from
those days, when radios were sold to work on either distribution
system.

On Fri, 09 Oct 2009 09:04:47 -0700, windcrest wrote:
I still have an old AC/DC radio from
those days, when radios were sold to work on either distribution
system.

Hmm, that triggered a memory. I used to have an AC/DC one from the '60s -
manual switch, and you could feed 12V DC in on the same power socket as
AC. I doubt something like that would pass H+S these days, never mind the
amount of people who'd try to feed it domestic AC with the switch on the
DC setting and fry the thing

cheers

Jules

bud-- wrote:
The Daring Dufas wrote:
Proteus IIV wrote:

YOU ARE SOUNDING LIKE AN IDIOT

HOW DO YOU SUUPLY REATIVE ?

YOU SHOULD COMMIT HAIKIRI

IT'S CALLED REACTANCE

AND I AM NOT GOING TO SHOW YOU HOW TO ACHIEVE THAT HERE NOR ANYWHERE
ELSE

YOU WILL HAVE TO PAY THE PIPER DONKEY LIKE EVERYONE ELSE

OR JUST SHUT THE FLUX UP

PERMAMNENTLY !

I AM PROTEUS


Uh, Pro, buddy, there is medication for your problem.
Your county health department may be able to help you
out with a psychiatric referral. FLNF

TDD

It is a particularly ignorant troll that infests
alt.engineering.electrical.

Just ignore it like everyone else (except one of its equals).

I was being fecesious {sic}.

TDD

windcrest wrote:
On Oct 6, 7:11 pm, "Don Kelly" wrote:
"The Daring Dufas" wrote in ...



Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
James Sweet wrote:
My suggestion would be for a 48 volt DC system. Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC. The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages. The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
TDD
And what would be the advantage? The 78xx series are linear regulators,
they are in effect a regulated resistor that burns up the excess
voltage
in the form of heat. On top of that, they max out at 37V input at which
point a substantial heatsink is required to dissipate the heat. The end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.
You could use a switchmode regulator to get decent efficiency, but once
you've gone that route, you may as well just use 120V or 240VAC since
the additional components required are trivial.
Solar and wind power can easily integrate with the existing grid, with
the additional advantage of being able to sell excess capacity back to
the utility. The cost of the special inverter is low compared to what
the panels cost, and dropping all the time. This proposed DC system is
just reinventing the wheel with something inferior to what we already
have.
I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.
TDD
DC Power transmission lines are used to rid the line of skin effect
and allow the entire cross section of the conductor to carry current.
They are as yet only practical for long haul point to point
circuits.
--
Tom Horne
That's what I read. My only experience with high voltage power
transmission has been installing buried conduit, setting transformers,
making connections and splices on 15kv coaxial underground cable.
Of course there was all of the other wiring on the low voltage side
of the transformer including the facilities wiring. What I find
fascinating about the long haul high voltage DC power transmission systems
has to do with the changes in technology over the years to handle the
conversion of AC to DC then back again. The early mercury arc
valve systems have got to be a sight to behold. I can imagine a mad
scientist wearing super thick lensed glasses cackling in the background.
TDD
Even a 5Kw 6 phase converter was a sight to see- looked like an octopus
with glowing arms and a bright spot dancing on a dish of mercury.
Seriously the advantages of DC transmission has relatively little to do with
skin effect as conductors are typically ACSR with aluminum on the outside
and steel inside- and, at these voltages are grouped in bundles. The size
of the conductor has more to do with mechanical than electrical properties.
DC transmission at high voltages is economical for long lines where the
reduced cost of the line exceeds the added cost of the terminal equipment.
There are also some other technical advantages . This breakeven point is at
a much shorter distance for underground or underwater cable. DC back to back
terminals are often used where frequency differences (e.g. in Japan with
both 50 and 60 Hz systems) or stability concerns arise. They do have the
disadvantage that reasonable and economic circuit breakers for DC don't
exist and this means that the system is essentially point to point rather
than through an interconnected grid. In addition, conversion from one
voltage level to the next is bloody expensive, awkward and inefficient
compared to the use of AC transformers.
At low voltages, even for relatively short distances, DC is not a viable
option.

--
Don Kelly

cross out to reply- Hide quoted text -

- Show quoted text -


Thats why Westinghouse beat Edison in the early days of deciding what
electical distribution system to use, Westinghouse (scientist) wanted
AC, Edison (who was more of an inventor than a scientist) would not
let go of his prejudice for DC. I still have an old AC/DC radio from
those days, when radios were sold to work on either distribution
system.


Have you had any experience with high frequency AC power systems?
I've come across 400hz AC power in some old computer installations
and seen a lot of military surplus aircraft power equipment that
used 400hz AC power. My assumption has always been that higher the
frequency, the smaller the mass of the transformers not only making
equipment smaller but lighter.

TDD

On Oct 9, 12:16*pm, The Daring Dufas
wrote:
windcrest wrote:
On Oct 6, 7:11 pm, "Don Kelly" wrote:
"The Daring Dufas" wrote in ...

Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
James Sweet wrote:
My suggestion would be for a 48 volt DC system. Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC. The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages. The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
TDD
And what would be the advantage? The 78xx series are linear regulators,
they are in effect a regulated resistor that burns up the excess
voltage
in the form of heat. On top of that, they max out at 37V input at which
point a substantial heatsink is required to dissipate the heat. The end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.
You could use a switchmode regulator to get decent efficiency, but once
you've gone that route, you may as well just use 120V or 240VAC since
the additional components required are trivial.
Solar and wind power can easily integrate with the existing grid, with
the additional advantage of being able to sell excess capacity back to
the utility. The cost of the special inverter is low compared to what
the panels cost, and dropping all the time. This proposed DC system is
just reinventing the wheel with something inferior to what we already
have.
I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.
TDD
DC Power transmission lines are used to rid the line of skin effect
and allow the entire cross section of the conductor to carry current..
They are as yet only practical for long haul point to point
circuits.
--
Tom Horne
That's what I read. My only experience with high voltage power
transmission has been installing buried conduit, setting transformers,
making connections and splices on 15kv coaxial underground cable.
Of course there was all of the other wiring on the low voltage side
of the transformer including the facilities wiring. What I find
fascinating about the long haul high voltage DC power transmission systems
has to do with the changes in technology over the years to handle the
conversion of AC to DC then back again. The early mercury arc
valve systems have got to be a sight to behold. I can imagine a mad
scientist wearing super thick lensed glasses cackling in the background.
TDD
Even a 5Kw 6 phase converter was a sight to see- looked *like an octopus
with glowing arms and a bright spot dancing on a dish of mercury.
Seriously the advantages of DC transmission has relatively little to do with
skin effect as conductors are typically ACSR with aluminum on the outside
and steel inside- and, at these voltages are grouped in bundles. *The size
of the conductor has more to do with mechanical than electrical properties.
DC transmission at high voltages is economical for long lines where the
reduced cost of the line exceeds the added cost of the terminal equipment.
There are also some other technical advantages . This breakeven point is at
a much shorter distance for underground or underwater cable. DC back to back
terminals are often used where frequency differences (e.g. in Japan with
both 50 and 60 Hz systems) or stability concerns arise. They do have the
disadvantage that reasonable and economic circuit breakers for DC don't
exist and this means that *the system is essentially point to point rather
than through an interconnected grid. In addition, conversion from one
voltage level to the next is bloody expensive, awkward and inefficient
compared to the *use of AC transformers.
At low voltages, even for relatively short distances, DC is not a viable
option.

--
Don Kelly

cross out to reply- Hide quoted text -

- Show quoted text -

Thats why Westinghouse beat Edison in the early days of deciding what
electical distribution system to use, Westinghouse (scientist) wanted
AC, Edison (who was more of an inventor than a scientist) would not
let go of his prejudice for DC. *I still have an old AC/DC radio from
those days, when radios were sold to work on either distribution
system.

Have you had any experience with high frequency AC power systems?
I've come across 400hz AC power in some old computer installations
and seen a lot of military surplus aircraft power equipment that
used 400hz AC power. My assumption has always been that higher the
frequency, the smaller the mass of the transformers not only making
equipment smaller but lighter.

Filter capacitors and inductors too. It's not uncommon for switching
power supplies to be above 1MHz, also to keep the size of components
(and costs) small.

....and transformers get *very* big at DC.

"windcrest" wrote in message
...
On Oct 6, 7:11 pm, "Don Kelly" wrote:
"The Daring Dufas" wrote in
...



Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
James Sweet wrote:

My suggestion would be for a 48 volt DC system. Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC. The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages. The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
TDD
And what would be the advantage? The 78xx series are linear
regulators,
they are in effect a regulated resistor that burns up the excess
voltage
in the form of heat. On top of that, they max out at 37V input at
which
point a substantial heatsink is required to dissipate the heat. The
end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.
You could use a switchmode regulator to get decent efficiency, but
once
you've gone that route, you may as well just use 120V or 240VAC since
the additional components required are trivial.
Solar and wind power can easily integrate with the existing grid,
with
the additional advantage of being able to sell excess capacity back
to
the utility. The cost of the special inverter is low compared to what
the panels cost, and dropping all the time. This proposed DC system
is
just reinventing the wheel with something inferior to what we already
have.
I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.

TDD

DC Power transmission lines are used to rid the line of skin effect
and allow the entire cross section of the conductor to carry current.
They are as yet only practical for long haul point to point
circuits.

--
Tom Horne

That's what I read. My only experience with high voltage power
transmission has been installing buried conduit, setting transformers,
making connections and splices on 15kv coaxial underground cable.
Of course there was all of the other wiring on the low voltage side
of the transformer including the facilities wiring. What I find
fascinating about the long haul high voltage DC power transmission
systems
has to do with the changes in technology over the years to handle the
conversion of AC to DC then back again. The early mercury arc
valve systems have got to be a sight to behold. I can imagine a mad
scientist wearing super thick lensed glasses cackling in the background.

TDD

Even a 5Kw 6 phase converter was a sight to see- looked like an octopus
with glowing arms and a bright spot dancing on a dish of mercury.
Seriously the advantages of DC transmission has relatively little to do
with
skin effect as conductors are typically ACSR with aluminum on the outside
and steel inside- and, at these voltages are grouped in bundles. The size
of the conductor has more to do with mechanical than electrical
properties.
DC transmission at high voltages is economical for long lines where the
reduced cost of the line exceeds the added cost of the terminal equipment.
There are also some other technical advantages . This breakeven point is
at
a much shorter distance for underground or underwater cable. DC back to
back
terminals are often used where frequency differences (e.g. in Japan with
both 50 and 60 Hz systems) or stability concerns arise. They do have the
disadvantage that reasonable and economic circuit breakers for DC don't
exist and this means that the system is essentially point to point rather
than through an interconnected grid. In addition, conversion from one
voltage level to the next is bloody expensive, awkward and inefficient
compared to the use of AC transformers.
At low voltages, even for relatively short distances, DC is not a viable
option.

--
Don Kelly

cross out to reply- Hide quoted text -

- Show quoted text -


Thats why Westinghouse beat Edison in the early days of deciding what
electical distribution system to use, Westinghouse (scientist) wanted
AC, Edison (who was more of an inventor than a scientist) would not
let go of his prejudice for DC. I still have an old AC/DC radio from
those days, when radios were sold to work on either distribution
system.

Westinghouse was an inventor, and entrepreneur (as was Edison) - who
recognized good ideas when he saw them and a way to get around Edison's
stranglehold on the electrical "lighting" systems. This was weakened before
Tesla, by Gaulard and Gibbs who invented the transformer (1886 or
thereabouts for the first AC transmission). - making long distance
transmission possible. polyphase machines invented by Tesla were the icing
on the cake, and 3 phase systems followed soon after. Edison wanted to hang
onto his empire- so fought tooth and nail against AC- he had a good thing
going. Tesla once worked for him but got shafted.
As for the radio- If I recall correctly, until the late 1920's all radios
were battery powered. Then AC/DC units came into use. Better ones used
transformers to get the various voltages, filament and plate (replacing the
old A and B batteries).
The typical smaller radios that were sold in the 40's and 50's would work
on DC as they did not have a transformer, and tubes operated on the
rectified line voltage, with tube filaments in series. This was done, not
with intent to use them on DC supplies but because they were considerably
cheaper to build but could have a hot chassis (safety? what's that?).

The history of those times is very interesting. An often ignored inventor
who thought things out before trying them (as opposed to the Edison
approach) , was Elihu Thompson.

--
Don Kelly

cross out to reply

"Stuart" wrote in message
...
In article ,
The Daring Dufas wrote:
Have you had any experience with high frequency AC power systems?
I've come across 400hz AC power in some old computer installations
and seen a lot of military surplus aircraft power equipment that
used 400hz AC power. My assumption has always been that higher the
frequency, the smaller the mass of the transformers not only making
equipment smaller but lighter.

Very common (standard?) in aircraft.



In addition to smaller generator/motor and transformer sizes and weights
for a given power, the 400Hz machines can be driven at higher speeds
eliminating some or all gearing in high rpm aircraft usage (up to 24000
rpm at 400 Hz
vs up to 3600 rpm at 60 Hz. ).
For aircraft the distances involved are short so that inductance and
capacitance are not a problem .

In general, for land based applications the advantages are outweighed by the
disadvantages because of the distances involved.

Switching power supplies were not an option in those days.

--
Don Kelly

cross out to reply

Don Kelly wrote:

"windcrest" wrote in message
...
On Oct 6, 7:11 pm, "Don Kelly" wrote:
"The Daring Dufas" wrote in
...



Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
James Sweet wrote:

My suggestion would be for a 48 volt DC system. Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC. The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages. The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
TDD
And what would be the advantage? The 78xx series are linear
regulators,
they are in effect a regulated resistor that burns up the excess
voltage
in the form of heat. On top of that, they max out at 37V input at
which
point a substantial heatsink is required to dissipate the heat.
The end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.
You could use a switchmode regulator to get decent efficiency,
but once
you've gone that route, you may as well just use 120V or 240VAC
since
the additional components required are trivial.
Solar and wind power can easily integrate with the existing grid,
with
the additional advantage of being able to sell excess capacity
back to
the utility. The cost of the special inverter is low compared to
what
the panels cost, and dropping all the time. This proposed DC
system is
just reinventing the wheel with something inferior to what we
already
have.
I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.

TDD

DC Power transmission lines are used to rid the line of skin effect
and allow the entire cross section of the conductor to carry current.
They are as yet only practical for long haul point to point
circuits.

--
Tom Horne

That's what I read. My only experience with high voltage power
transmission has been installing buried conduit, setting transformers,
making connections and splices on 15kv coaxial underground cable.
Of course there was all of the other wiring on the low voltage side
of the transformer including the facilities wiring. What I find
fascinating about the long haul high voltage DC power transmission
systems
has to do with the changes in technology over the years to handle the
conversion of AC to DC then back again. The early mercury arc
valve systems have got to be a sight to behold. I can imagine a mad
scientist wearing super thick lensed glasses cackling in the
background.

TDD

Even a 5Kw 6 phase converter was a sight to see- looked like an octopus
with glowing arms and a bright spot dancing on a dish of mercury.
Seriously the advantages of DC transmission has relatively little to
do with
skin effect as conductors are typically ACSR with aluminum on the outside
and steel inside- and, at these voltages are grouped in bundles. The size
of the conductor has more to do with mechanical than electrical
properties.
DC transmission at high voltages is economical for long lines where the
reduced cost of the line exceeds the added cost of the terminal
equipment.
There are also some other technical advantages . This breakeven point
is at
a much shorter distance for underground or underwater cable. DC back
to back
terminals are often used where frequency differences (e.g. in Japan with
both 50 and 60 Hz systems) or stability concerns arise. They do have the
disadvantage that reasonable and economic circuit breakers for DC don't
exist and this means that the system is essentially point to point rather
than through an interconnected grid. In addition, conversion from one
voltage level to the next is bloody expensive, awkward and inefficient
compared to the use of AC transformers.
At low voltages, even for relatively short distances, DC is not a viable
option.

--
Don Kelly

cross out to reply- Hide quoted text -

- Show quoted text -


Thats why Westinghouse beat Edison in the early days of deciding what
electical distribution system to use, Westinghouse (scientist) wanted
AC, Edison (who was more of an inventor than a scientist) would not
let go of his prejudice for DC. I still have an old AC/DC radio from
those days, when radios were sold to work on either distribution
system.

Westinghouse was an inventor, and entrepreneur (as was Edison) - who
recognized good ideas when he saw them and a way to get around Edison's
stranglehold on the electrical "lighting" systems. This was weakened
before Tesla, by Gaulard and Gibbs who invented the transformer (1886
or thereabouts for the first AC transmission). - making long distance
transmission possible. polyphase machines invented by Tesla were the
icing on the cake, and 3 phase systems followed soon after. Edison
wanted to hang onto his empire- so fought tooth and nail against AC- he
had a good thing going. Tesla once worked for him but got shafted.
As for the radio- If I recall correctly, until the late 1920's all
radios were battery powered. Then AC/DC units came into use. Better
ones used transformers to get the various voltages, filament and plate
(replacing the old A and B batteries).
The typical smaller radios that were sold in the 40's and 50's would
work on DC as they did not have a transformer, and tubes operated on the
rectified line voltage, with tube filaments in series. This was done,
not with intent to use them on DC supplies but because they were
considerably cheaper to build but could have a hot chassis (safety?
what's that?).

The history of those times is very interesting. An often ignored
inventor who thought things out before trying them (as opposed to the
Edison approach) , was Elihu Thompson.


When I was a kid, I got hold of an old tube type record player
that had a metal chassis, for some reason when I was playing
around with it on the back porch of our house, I got lit up.
DANG!! This was long before two wire cords had a wide bladed
neutral. With all the electrical devices I played with when
I was a kid, I'm surprised I ever survived.

TDD

"The Daring Dufas" wrote in message
...
Don Kelly wrote:

"windcrest" wrote in message
...
On Oct 6, 7:11 pm, "Don Kelly" wrote:
"The Daring Dufas" wrote in
...



Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
James Sweet wrote:

My suggestion would be for a 48 volt DC system. Plain
old telephone service uses 48 volts DC for battery and
PoE, power over Ethernet is usually 48 volts DC. The
wire size could be smaller than that for a lower voltage
system and the 78xx type regulators are very inexpensive
and come in a variety of wattage ratings for stepping
down the voltages. The technology to pull it off is not
exotic and can be done with all off the shelf parts.
Solar and wind power could integrate quite easily with
such a system.
TDD
And what would be the advantage? The 78xx series are linear
regulators,
they are in effect a regulated resistor that burns up the excess
voltage
in the form of heat. On top of that, they max out at 37V input at
which
point a substantial heatsink is required to dissipate the heat.
The end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.
You could use a switchmode regulator to get decent efficiency,
but once
you've gone that route, you may as well just use 120V or 240VAC
since
the additional components required are trivial.
Solar and wind power can easily integrate with the existing grid,
with
the additional advantage of being able to sell excess capacity
back to
the utility. The cost of the special inverter is low compared to
what
the panels cost, and dropping all the time. This proposed DC
system is
just reinventing the wheel with something inferior to what we
already
have.
I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.

TDD

DC Power transmission lines are used to rid the line of skin effect
and allow the entire cross section of the conductor to carry current.
They are as yet only practical for long haul point to point
circuits.

--
Tom Horne

That's what I read. My only experience with high voltage power
transmission has been installing buried conduit, setting transformers,
making connections and splices on 15kv coaxial underground cable.
Of course there was all of the other wiring on the low voltage side
of the transformer including the facilities wiring. What I find
fascinating about the long haul high voltage DC power transmission
systems
has to do with the changes in technology over the years to handle the
conversion of AC to DC then back again. The early mercury arc
valve systems have got to be a sight to behold. I can imagine a mad
scientist wearing super thick lensed glasses cackling in the
background.

TDD

Even a 5Kw 6 phase converter was a sight to see- looked like an octopus
with glowing arms and a bright spot dancing on a dish of mercury.
Seriously the advantages of DC transmission has relatively little to do
with
skin effect as conductors are typically ACSR with aluminum on the
outside
and steel inside- and, at these voltages are grouped in bundles. The
size
of the conductor has more to do with mechanical than electrical
properties.
DC transmission at high voltages is economical for long lines where the
reduced cost of the line exceeds the added cost of the terminal
equipment.
There are also some other technical advantages . This breakeven point is
at
a much shorter distance for underground or underwater cable. DC back to
back
terminals are often used where frequency differences (e.g. in Japan with
both 50 and 60 Hz systems) or stability concerns arise. They do have the
disadvantage that reasonable and economic circuit breakers for DC don't
exist and this means that the system is essentially point to point
rather
than through an interconnected grid. In addition, conversion from one
voltage level to the next is bloody expensive, awkward and inefficient
compared to the use of AC transformers.
At low voltages, even for relatively short distances, DC is not a viable
option.

--
Don Kelly

cross out to reply- Hide quoted text -

- Show quoted text -


Thats why Westinghouse beat Edison in the early days of deciding what
electical distribution system to use, Westinghouse (scientist) wanted
AC, Edison (who was more of an inventor than a scientist) would not
let go of his prejudice for DC. I still have an old AC/DC radio from
those days, when radios were sold to work on either distribution
system.

Westinghouse was an inventor, and entrepreneur (as was Edison) - who
recognized good ideas when he saw them and a way to get around Edison's
stranglehold on the electrical "lighting" systems. This was weakened
before Tesla, by Gaulard and Gibbs who invented the transformer (1886 or
thereabouts for the first AC transmission). - making long distance
transmission possible. polyphase machines invented by Tesla were the
icing on the cake, and 3 phase systems followed soon after. Edison
wanted to hang onto his empire- so fought tooth and nail against AC- he
had a good thing going. Tesla once worked for him but got shafted.
As for the radio- If I recall correctly, until the late 1920's all
radios were battery powered. Then AC/DC units came into use. Better
ones used transformers to get the various voltages, filament and plate
(replacing the old A and B batteries).
The typical smaller radios that were sold in the 40's and 50's would
work on DC as they did not have a transformer, and tubes operated on the
rectified line voltage, with tube filaments in series. This was done, not
with intent to use them on DC supplies but because they were considerably
cheaper to build but could have a hot chassis (safety? what's that?).

The history of those times is very interesting. An often ignored inventor
who thought things out before trying them (as opposed to the Edison
approach) , was Elihu Thompson.


When I was a kid, I got hold of an old tube type record player
that had a metal chassis, for some reason when I was playing
around with it on the back porch of our house, I got lit up. DANG!! This
was long before two wire cords had a wide bladed
neutral. With all the electrical devices I played with when
I was a kid, I'm surprised I ever survived.

TDD

---
Hey, you've got an old radio which has seen better days- maybe even missing
its case but still working - put it in the shop or better yet in the laundry
area. you might be lucky .
--
Don Kelly

cross out to reply

Thats why Westinghouse beat Edison in the early days of deciding what
electical distribution system to use, Westinghouse (scientist) wanted
AC, Edison (who was more of an inventor than a scientist) would not
let go of his prejudice for DC. I still have an old AC/DC radio from
those days, when radios were sold to work on either distribution
system.



AC/DC radios were born out of the great depression. It was the
Volkswagen Beetle of radios. The reason for the design was that it
eliminated the (expensive) power transformer by wiring all the tube
heaters in series and made the set much cheaper to manufacture. A useful
side effect of this was that it would work on either AC or DC. An
additional potentially very dangerous side effect is that depending on
which way the plug was inserted into the receptacle, the entire metal
chassis could be live, including shafts that would be exposed by a
missing knob.

The classic "All American Five" so named for the lineup of five tubes
used in virtually all of them was prolific up into at least the mid 60s.
It really is remarkable just how well it worked, despite circuit layout
and wiring techniques that would make an RF engineer cringe. It is
highly advisable to power these from an isolation transformer.

Incidentally, I read a few years back that it wasn't until the late
1990s that the last DC service was disconnected from a building,
somewhere in NY I think. I was amazed by how long it remained in use.

Jules wrote:
On Fri, 09 Oct 2009 09:04:47 -0700, windcrest wrote:
I still have an old AC/DC radio from
those days, when radios were sold to work on either distribution
system.

Hmm, that triggered a memory. I used to have an AC/DC one from the '60s -
manual switch, and you could feed 12V DC in on the same power socket as
AC. I doubt something like that would pass H+S these days, never mind the
amount of people who'd try to feed it domestic AC with the switch on the
DC setting and fry the thing

cheers

Jules



That's actually a bit different. The AC/DC radios he refers to use a
transformerless power supply with the tube heaters wired in series.
Yours likely wires the tube heaters in parallel with a vibrator to
supply B+ to the plates when running from batteries.

The worst offenders for radios being plugged into the wrong voltage are
32V farm radios. The old 32VDC rural systems used the same plugs and
receptacles as the 110VAC systems standard elsewhere, so it's common for
someone unknowledgeable to plug a farm radio into a 120V receptacle and
blow all the tube heaters.

Have you had any experience with high frequency AC power systems?
I've come across 400hz AC power in some old computer installations
and seen a lot of military surplus aircraft power equipment that
used 400hz AC power. My assumption has always been that higher the
frequency, the smaller the mass of the transformers not only making
equipment smaller but lighter.

TDD


That's exactly it. 400Hz power has been standard in aircraft for many
decades. Not only are the transformers smaller and lighter, but the
generators and motors too, and the filter capacitors in power supplies.

It's the reason switchmode power supplies run in the tens of kHz, and
some small ones are running as high as 1MHz. As the frequency increases,
switching losses in the semiconductors increase, but the size of the
energy storage components (inductors, transformers, capacitors)
decreases. A 60Hz transformer capable of supplying 300W might 15 lbs,
but a 20kHz transformer capable of the same power is less than a pound
and far more compact.

James Sweet wrote:


(snip)

Incidentally, I read a few years back that it wasn't until the late
1990s that the last DC service was disconnected from a building,
somewhere in NY I think. I was amazed by how long it remained in use.

Servicing some legacy elevator motors or building water pumps, IIRC.
Wikipedia has a pretty good writeup, linked from the 'current wars'
articles. Isn't their subway system still DC? I would never want to live
in NYC (or any huge city), but I do find the historical stuff about
their physical infrastructure quite fascinating. The occasional show on
History, Discovery, or similar channels always sets me off on an
internet hunt. If I could get shows like that on over-the-air TV (like
PBS in the old days), I'd probably get rid of my satt service.

--
aem sends...

On Thu, 8 Oct 2009 21:45:03 -0700 (PDT), Proteus IIV
wrote:


IT'S CALLED REACTANCE

Yeah, dip****... That is the response to magnetic flux and work.

It is referred to by ALL of us in the industry, as a reactive load.

Go away, you know nothing twit.

On Thu, 08 Oct 2009 23:50:40 -0500, The Daring Dufas
wrote:

Proteus IIV wrote:
On Oct 8, 11:04 pm, "Don Kelly" wrote:
"The Daring Dufas" wrote in ...

Don Kelly wrote:
"The Daring Dufas" wrote in message
...
Tom Horne wrote:
On Oct 4, 5:04 am, The Daring Dufas
wrote:
From my reading, the problem of capacitive reactance is also minimized
with the DC transmission lines.
That too, and that is a major benefit. However, there is still a reactive
problem at the receiving end where it is necessary to have the capacity to
supply reactive.====== This will be dependent on load and the particular control
of the system as a whole. For long lines this will be less than what would
otherwise be needed to compensate for line capacitance.

--
Don Kelly

cross out to reply

YOU ARE SOUNDING LIKE AN IDIOT

HOW DO YOU SUUPLY REATIVE ?

YOU SHOULD COMMIT HAIKIRI

IT'S CALLED REACTANCE

AND I AM NOT GOING TO SHOW YOU HOW TO ACHIEVE THAT HERE NOR ANYWHERE
ELSE

YOU WILL HAVE TO PAY THE PIPER DONKEY LIKE EVERYONE ELSE

OR JUST SHUT THE FLUX UP

PERMAMNENTLY !

I AM PROTEUS


Uh, Pro, buddy, there is medication for your problem.
Your county health department may be able to help you
out with a psychiatric referral. FLNF

TDD


Are you kidding? We are talking about NYC here. To them, his nut case
level is mild.