Whole house "battery" wiring/power...

[krw]

*CLOCK* radio!

Thought you might be raising chickens, too. ;-)

 

[James Sweet]

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.


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

Nor was I trying to. I've pointed out the faults all along, I was only
commenting on some of the points. I'm not the OP.

 

[James Sweet]

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

Tesla and Edison were both great contributors. Tesla's strength was as a
scientist and engineer, pioneering the technologies themselves, with a
solid understanding of the technical details. Edison was more of a
classical inventor and experimenter, having little real engineering
knowledge, he tinkered and experimented through trial and error, mostly
improving existing concepts. Edison's great strength in all this was
that he was one of the first to see the big picture, recognizing that a
light bulb was a useless curiosity without the infrastructure needed to
generate, distribute, control, and meter electricity, manufacture, and
distribute the hardware to do so. He designed generators, switches, fuse
panels, the screw base and socket we still use today, watthour meters,
the whole system. Edison, Westinghouse, and Tesla all contributed
greatly and without any one of them we would not be where we are today.

 

[krw]

Nor was I trying to. I've pointed out the faults all along, I was only
commenting on some of the points.

My points were more about the *stupid* ideas of using linear
regulators and DC distribution. I read your post as if DC
distribution was somehow reasonable if linears weren't used.

Sure, DC-DC converters are quite similar to switching power supplies.
That's rather obvious.

I'm not the OP.

That was simple enough to figure out. ;-)

 

[The Daring Dufas]

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


Yes, all telling you that your idea is stupid.


I agree. Everyone agrees that your idea is stupid.


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


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


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


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


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

 

[krw]

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
shit. 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.

 

[The Daring Dufas]

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.

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

 

[James Sweet]

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.

Skin effect is not much of an issue at 50-60Hz. It really only comes
into play once you get up into the tens of kHz.

 

[James Sweet]

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

MARs in that power range are big steel tanks that look much like large
distribution transformers, they're not terribly interesting to see.

The smaller glass ones are indeed impressive though. They were used a
lot for subway traction supplies.

http://images.google.com/imgres?img...?q=mercury+arc+rectifier&gbv=2&hl=en&safe=off

 

[George]

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

 

[The Daring Dufas]

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

 

[The Daring Dufas]

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

 

[James Sweet]

Part of the pumping system was a Mercury vapour pump! Can't remember how
they worked it's too long ago. There probably were traps of some sort or
other, otherwise we would have been forever topping up the Mercury, which
we weren't. However, back in those days I don't think anyone was too
concerned about it. I was never really involved in the maintenance of the
system anyway as my job was operational and looking after the RF side of
things.

Stuart

Mercury diffusion pumps were common. They saw a lot of use in vacuum
tube and light bulb production. There's plenty of material out there
explaining how they work, but they require a mechanical roughing pump to
get most of the gas out first. They were replaced by oil diffusion
pumps, and more recently have been getting phased out of most
applications by turbomolecular pumps. Neon sign guys still use mostly
oil diffusion pumps, as they're much less prone to damage by foreign
matter than turbopumps. They're a lot cheaper too.

 

[James Sweet]

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

The draw is usually a watt or two, but the power factor of an un-loaded
wall wart is pretty bad, so it can be 5-10VA. Under load, the iron
transformer type are normally around 50% efficient.

 

[Don Kelly]

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.

 

[The Daring Dufas]

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

 

[Mycelium]

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.

 

[Jules]

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

 

[Archimedes' Lever]

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.

 

[krw]

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

AlwaysWrong strikes again.

http://science.slashdot.org/article.pl?sid=07/11/16/225213
http://cityroom.blogs.nytimes.com/2007/11/14/off-goes-the-power-current-started-by-thomas-edison/