Â* Could I have some advice please.
Â* I need to get a twelve volt, 1/2 amp supply five
hundred metres up a hill.
I do have a fence a metre high made from wooden posts and
seven runs of Num eight (4 mil) galvanised steel
wire.
Is it feasible to use two of these wires to carry twelve
volts that distance ?
Thank you.
Â*

grumpyoldhori writes:

Is it feasible to use two of these wires to carry twelve
volts that distance ?

No.

On Fri, 25 Apr 2008 23:33:18 -0500, Richard J Kinch
wrote:

grumpyoldhori writes:

Is it feasible to use two of these wires to carry twelve
volts that distance ?

No.

I'd say yes.

"Don Foreman" wrote in message
...
On Fri, 25 Apr 2008 23:33:18 -0500, Richard J Kinch
wrote:

grumpyoldhori writes:

Is it feasible to use two of these wires to carry twelve
volts that distance ?

No.

I'd say yes.

Probably need to start with 24 volts to get 12 at the top. It will have
about 15+ ohms total resistance (~3000 feet of wire). Is the load constant?
Like a lamp or such?

Is the wire insulated from the wood post? He could use 24 volts AC to a
transformer at the top and convert to DC at the end.

Tom

On Sat, 26 Apr 2008 03:31:36 -0400, "Tom M"
wrote:


"Don Foreman" wrote in message
.. .
On Fri, 25 Apr 2008 23:33:18 -0500, Richard J Kinch
wrote:

grumpyoldhori writes:

Is it feasible to use two of these wires to carry twelve
volts that distance ?

No.

I'd say yes.

Probably need to start with 24 volts to get 12 at the top. It will have
about 15+ ohms total resistance (~3000 feet of wire). Is the load constant?
Like a lamp or such?

Is the wire insulated from the wood post? He could use 24 volts AC to a
transformer at the top and convert to DC at the end.

Tom

I figure 7.7 ohms for 1000 meters of 4 millimeter iron (steel) wire,
so drop of about 3.9 volts at 0.5 amp. I'd find a source of 16 to 24
VDC for the drive end, put a 12-volt regulator (e.g. LM7812) on the
load end. The regulator costs about a dollar. It'll need a bit of
heatsink, perhaps a piece of ally 10 cm square or so. It can be bent
as desired to fit in a space.

Don Foreman wrote:

I figure 7.7 ohms for 1000 meters of 4 millimeter iron (steel) wire,
so drop of about 3.9 volts at 0.5 amp. I'd find a source of 16 to 24
VDC for the drive end, put a 12-volt regulator (e.g. LM7812) on the
load end. The regulator costs about a dollar. It'll need a bit of
heatsink, perhaps a piece of ally 10 cm square or so. It can be bent
as desired to fit in a space.


Don't forget the bypass capacitors for that regulator, or it will be
very unstable. Also, you need to protect it from lightning induced
surges. Transfomers at both ends would help, mut make sure they are
rated for 2500 VAC insulation. Split bobbin transformers would be a
good choice. They can be found as surplus, or salvaged from junk
equipment.


--
http://improve-usenet.org/index.html


Use any search engine other than Google till they stop polluting USENET
with porn and junk commercial SPAM

If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm

On Sat, 26 Apr 2008 03:31:36 -0400, "Tom M"
wrote:


"Don Foreman" wrote in message
.. .
On Fri, 25 Apr 2008 23:33:18 -0500, Richard J Kinch
wrote:

grumpyoldhori writes:

Is it feasible to use two of these wires to carry twelve
volts that distance ?

No.

I'd say yes.

Probably need to start with 24 volts to get 12 at the top. It will have
about 15+ ohms total resistance (~3000 feet of wire). Is the load constant?
Like a lamp or such?

Is the wire insulated from the wood post? He could use 24 volts AC to a
transformer at the top and convert to DC at the end.

Tom

Indeed. AC up, convert to dc to avoid the losses

Gunner

Political Correctness is a doctrine fostered by a delusional,
illogical liberal minority, and rabidly promoted by an
unscrupulous mainstream media, which holds forth the
proposition that it is entirely possible to pick up a turd by the clean end.

grumpyoldhori wrote:
Could I have some advice please.
I need to get a twelve volt, 1/2 amp supply five
hundred metres up a hill.
I do have a fence a metre high made from wooden posts and
seven runs of Num eight (4 mil) galvanised steel
wire.
Is it feasible to use two of these wires to carry twelve
volts that distance ?
Thank you.



If it was me, I run some trials.
Id get a 12 volt car battery ,connect the positive to one of your
galvanised wires then at the 500 meter point conect this wire to one say
2 strands down,come back to the battery and put a volt meter between the
retun wire and the battery negative.
this will show you the voltage losss/drop over the 1000m length.
what ever this is, lets say for example 12 volts, youll then have to
add another 6 volt battery to make the input voltage 18 to get
12 volts at the 500 meter point.
Run the trialand let us all know what the values are.
Even tho its up hill that shouldnt make much difference to what you get out.
To replace or run a copper line 1000meters is a much better way to go.
tho the cost wold be high.
Depends where you are.

On Sat, 26 Apr 2008 05:27:37 GMT, Ted Frater
wrote:

grumpyoldhori wrote:
Could I have some advice please.
I need to get a twelve volt, 1/2 amp supply five
hundred metres up a hill.
I do have a fence a metre high made from wooden posts and
seven runs of Num eight (4 mil) galvanised steel
wire.
Is it feasible to use two of these wires to carry twelve
volts that distance ?
Thank you.



If it was me, I run some trials.
Id get a 12 volt car battery ,connect the positive to one of your
galvanised wires then at the 500 meter point conect this wire to one say
2 strands down,come back to the battery and put a volt meter between the
retun wire and the battery negative.
this will show you the voltage losss/drop over the 1000m length.
what ever this is, lets say for example 12 volts, youll then have to
add another 6 volt battery to make the input voltage 18 to get
12 volts at the 500 meter point.
Run the trialand let us all know what the values are.
Even tho its up hill that shouldnt make much difference to what you get out.
To replace or run a copper line 1000meters is a much better way to go.
tho the cost wold be high.
Depends where you are.

ted what has going up the hill got to do with it?
please explain that, it really has me interested.

Stealth Pilot

Stealth Pilot wrote:
On Sat, 26 Apr 2008 05:27:37 GMT, Ted Frater
wrote:


grumpyoldhori wrote:

Could I have some advice please.
I need to get a twelve volt, 1/2 amp supply five
hundred metres up a hill.
I do have a fence a metre high made from wooden posts and
seven runs of Num eight (4 mil) galvanised steel
wire.
Is it feasible to use two of these wires to carry twelve
volts that distance ?
Thank you.



If it was me, I run some trials.
Id get a 12 volt car battery ,connect the positive to one of your
galvanised wires then at the 500 meter point conect this wire to one say
2 strands down,come back to the battery and put a volt meter between the
retun wire and the battery negative.
this will show you the voltage losss/drop over the 1000m length.
what ever this is, lets say for example 12 volts, youll then have to
add another 6 volt battery to make the input voltage 18 to get
12 volts at the 500 meter point.
Run the trialand let us all know what the values are.
Even tho its up hill that shouldnt make much difference to what you get out.
To replace or run a copper line 1000meters is a much better way to go.
tho the cost wold be high.
Depends where you are.


ted what has going up the hill got to do with it?
please explain that, it really has me interested.

Stealth Pilot

I put that in just for fun to see if anyone might query it.
Water wont flow up hill unless pushed.
Tho as an afterethought, there might just be a miniscule slowing of the
electrons uphill . Effect caused by gravity, if electrons hace some
mass. Probably un measuable
Thanks for responding
Ted
Dorset
UK

Ted Frater wrote:
grumpyoldhori wrote:

Could I have some advice please.
I need to get a twelve volt, 1/2 amp supply five hundred metres up a
hill.
I do have a fence a metre high made from wooden posts and seven runs
of Num eight (4 mil) galvanised steel wire.
Is it feasible to use two of these wires to carry twelve volts that
distance ?
Thank you.



If it was me, I run some trials.
Id get a 12 volt car battery ,connect the positive to one of your
galvanised wires then at the 500 meter point conect this wire to one say
2 strands down,come back to the battery and put a volt meter between the
retun wire and the battery negative.
You have to supply the intended load for there to be any voltage
drop.

Jon

"grumpyoldhori" wrote in message
...
Could I have some advice please.
I need to get a twelve volt, 1/2 amp supply five
hundred metres up a hill.
I do have a fence a metre high made from wooden posts and
seven runs of Num eight (4 mil) galvanised steel
wire.
Is it feasible to use two of these wires to carry twelve
volts that distance ?
Thank you.

Like the others said, experiments will give you the answer for sure. But you
can get a reasonable answer by calculating things ahead. For instance:

I shall make an assumption that resistivity of steel is the same as iron
(1xe-7) and that your wire has a diameter of 2 mm (easy on the calculations
and probably generous). This gives the resistance of a 500 m long steel wire
as 16 ohms, give or take. Thus passing 0.5 Amp current will cause a drop of
8 V, leaving you with only 4V up the hill...

A copper wire of the same diameter and length is about ten times more
conductive, thus the drop would be only 0.8V.

--
Michael Koblic,
Campbell River, BC

Michael Koblic wrote:
"grumpyoldhori" wrote in message
...
Could I have some advice please.
I need to get a twelve volt, 1/2 amp supply five
hundred metres up a hill.
I do have a fence a metre high made from wooden posts and
seven runs of Num eight (4 mil) galvanised steel
wire.
Is it feasible to use two of these wires to carry twelve
volts that distance ?
Thank you.


If the duty cycle was fairly low, I would look at using a 12v SLA
battery ( or maybe an old car battery), a small solar panel and a
trickle charger to keep it toped up.
As others have said, the resistance of the steel wire would be too high
and the cost of running large enough copper conductors ( to minimise
volt drop) that distance, would be too expensive.
What is the application and estimated amount of use per day?

Stephen Robinson wrote:

What is the application and estimated amount of use per day?

Running a Linksys wireless router on a hop for a
microwave link.
The output power is only 100mw. but the router draws
five watts on average to power it's board etc.
Running 24/7.
Looked at solar and running copper wire, both came
to around NZ $600
Which is why I am keen on using the steel wire if
possible.

On Sat, 26 Apr 2008 19:09:04 +1200, the renowned grumpyoldhori
wrote:

Stephen Robinson wrote:

What is the application and estimated amount of use per day?

Running a Linksys wireless router on a hop for a
microwave link.
The output power is only 100mw. but the router draws
five watts on average to power it's board etc.
Running 24/7.
Looked at solar and running copper wire, both came
to around NZ $600
Which is why I am keen on using the steel wire if
possible.

Okay, the router comes with a 'universal' SMPS wall-wart, yes?

How about using TWO 230:24 (eg. 1A rating) transformers to send the
power down your wires at 24VAC/50Hz, and step it up at the other end.
The wall-wart will tolerate as low an input as 100VAC or so, so if the
numbers we have for resistance are in the right ballpark you should be
okay (easy enough to short them at one end and measure the (loop)
resistance at the other. If it's around 35 ohms you should see around
150VAC at the output of the downstream transformer with a 6W load (if
the 6W is from the nameplate, rather than measurement, expect to see a
fair bit higher than that-- mabe 180 or 200VAC).

Although this may appear to be a more complex and expensive answer
than some others, it should give you a stable regulated supply for the
router, and at least has a good chance of surviving a nearby lightning
strike (put an arrestor at each low voltage end, before the
tranformer, as well as fuses or circuit breakers to protect against
shorts). Going directly in with DC, I think you'll be buying, and
configuring, a new router after every few electrical storms. The
transformers provide isolation against common mode voltage (assuming
the arrestor breaks down before the transformer insulation) and will
saturate when presented with a high normal mode voltage.



Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

On Sat, 26 Apr 2008 19:09:04 +1200, grumpyoldhori
wrote:

Stephen Robinson wrote:

What is the application and estimated amount of use per day?

Running a Linksys wireless router on a hop for a
microwave link.
The output power is only 100mw. but the router draws
five watts on average to power it's board etc.
Running 24/7.
Looked at solar and running copper wire, both came
to around NZ $600
Which is why I am keen on using the steel wire if
possible.

To get the distance at lower voltage drop, use 50 Hz or 60 Hz AC
dropped down from mains power - I would start the experiment with a 24
VAC input using the top (#1) wire as a "guard wire" grounded lightning
sink, with a ground lead going down the back side of the post to
ground rods at all the high points along the route. If lightning is
going to hit, you want to try and divert it from your power leads.

Make the #2 and #3 wires from the top your power leads, taken loose
from the fenceposts and mounted on ceramic insulators, and see how the
voltage is at the far end under load. The insulators will cost a bit,
but increase efficiency a lot - especially with the existing wire
stapled to wooden posts, when it rains the power will /all/ go away as
it leaks between the wires at 200 high-resistance shorts. When you
are only starting with 50 VA or less at the feed end it doesn't take
much loss at each post to suck it all up.

Anything below 50V with a current limited source is considered Class
2 Wiring in the US, and IIRC the rest of the world is about the same.
It will give the cows and sheep a tingle if they touch it, but that's
about it - much lower voltage than a fence shocker generator, but you
still want to use only enough voltage to get the job done.

At the feed end, my best guess for a starting point would be a 240V
to 24V at 50VA transformer meant for running Air Conditioning
controls, they are reasonably cheap. Fuses on both sides, and a
healthy lightning arrestor tied to a good ground rod.

Telephone lightning arrestors should work perfectly for that voltage
and be reasonably priced, they have about a 150V strike-over because
ringing voltage is around 120V AC 20 Hz. And the newer three terminal
gas-tube arrestor devices form a plasma and clamp both lines of the
pair to ground at once, to avoid sneak current failures.

If your area gets nailed by lightning often, you could also put
arrestors at all those mid-run ground rod locations. But due to added
expense you might want to wait till the first time it all gets "blowed
up good" and you realize it wasn't enough. Your call...

Wherever there is a gate, bury a length of PVC Plastic conduit with
the long sweep ells between the fence posts and under the opening.
Take the two power and one ground lead and convert to heavy gauge
stranded copper wire for the short run, then back to fence wires.
Might be a good location for a ground rod.

At the top of the hill you attach another healthy lightning arrestor
across the two power leads connected to a ground rod, then rectify and
regulate to the 12V DC the Ethernet repeater is going to want. And
put a healthy crowbar zener on the 12V DC output, to try and save the
repeater from a lightning strike or regulation failure.

If it all works as planned, go to a local print shop and have simple
warning signs made up - Print them two-up on A4 Goldenrod or Red paper
and cut in half (5" x 8") then heat laminated with a large border, and
staple them to every fourth or fifth fence post through the laminated
border. They will last several years if the paper remains sealed off.

"Warning - avoid contact with insulated fence wires. 24 VAC Class II
Current Limited power for Wi-Fi Ethernet repeater system on top of
hill for the (Name) residence. Safe for accidental contact. Please
do not short or ground fence wires. Enquires contact Hori at
(address/phone)."

Nothing fancy, but keeps the kiddies from playing with it, the local
loons from inventing UFO conspiracy theories (Yeah, as if that would
be enough to stop them...) ;-) and the local Law Enforcement/ Fire/
Wildlife authorities from freaking out about exposed wires.

-- Bruce --

grumpyoldhori wrote:
Stephen Robinson wrote:


What is the application and estimated amount of use per day?


Running a Linksys wireless router on a hop for a
microwave link.
The output power is only 100mw. but the router draws
five watts on average to power it's board etc.
Running 24/7.
Looked at solar and running copper wire, both came
to around NZ $600
Which is why I am keen on using the steel wire if
possible.


Ohh, this is different. Hopefully the router isn't too
expensive, because any lightning anywhere nearby will be picked
up by the long run of straight wire and deliver a massive ZAP to
the router. You will need to clean and solder any
splices/joints in the wire. I'd look carefully at rigging a
low-voltage transformer at the source end to run something like
24 - 36 V AC on the wire, and then converting to DC with a
transformer/rectifier at the router. This might give you a
little isolation at the router end, too, which might keep lesser
lightning events from frying it.

This can definitely be made to work, but due to the high
resistance of the wire, it takes just a little more complexity
to do it. The 24 or 36 V transformer at the source end
(remember to fuse it to protect against something shorting the
fence) should be easily found, might even be able to find a
wall-wart with that kind of output. For the router end, you
could use a transformer with a tapped secondary as an
autotransformer (although that defeats the isolation mentioned
earlier) to bring the 24-36 V from the fence down to the ~12 V
needed for the router. Also, a transformer with both 12 and 24
or 36 V secondaries could be used, connect input to the higher
secondary, output from the lower one. Leave the 230 V primary
disconnected and taped off.

Jon

On Sat, 26 Apr 2008 19:09:04 +1200, grumpyoldhori
wrote:

Stephen Robinson wrote:

What is the application and estimated amount of use per day?

Running a Linksys wireless router on a hop for a
microwave link.
The output power is only 100mw. but the router draws
five watts on average to power it's board etc.
Running 24/7.
Looked at solar and running copper wire, both came
to around NZ $600
Which is why I am keen on using the steel wire if
possible.
Do your calcs for voltage drop at .4 amp and see if you can just put
higher voltage in to counteract the drop. I'd throw 24 at it and use a
7812 regulator to control the voltage at the router. Also be VERY
carefull if you are in a thunderstorm area. Non twisted pair is a
GREAT antenna. A friend was loosing his fence charger every time
lightning struck within 2 miles untill we installed a surge arrester
(air core choke and spark-gap) His 3 miles of fence was picking up
several 10s of thousands of volts (at low current) blowing the outputs
on the fence charger. With the choke installed it's been trouble free
for over 5 years.
** Posted from http://www.teranews.com **

On Sat, 26 Apr 2008 19:09:04 +1200, grumpyoldhori wrote:

Stephen Robinson wrote:

What is the application and estimated amount of use per day?

Running a Linksys wireless router on a hop for a
microwave link.
The output power is only 100mw. but the router draws
five watts on average to power it's board etc.
Running 24/7.
Looked at solar and running copper wire, both came
to around NZ $600
Which is why I am keen on using the steel wire if
possible.

Hi Grumpy, a trip away from NZ.gen?
I used a car battery with a solar panel charger for a gate opener, which
worked well. A car battery (or 2 in parallel for more capacity) is cheap
and easy to get and should have enough capacity to run the router for days
of darkness. The solar panel was pretty cheap as well for a smaller size,
although this was a few years ago.
It has the advantage for being portable too, so you are not stuck with
having it by a fence.

Phone companies used to use copper clad steel on poles.

Maybe there is some still hanging or some in the phone yard sitting.

I'd talk to them if the phone or power company has scrap line for
this type of use. Might find so. Might find a few to help string
some of which they provide.

Even a bundle of twisted wire could be used - sets of lines in parallel.

The zinc might not be considered in the estimates either. But it leaches off.


I think myself I'd send AC - 36V at 1/3 the current and voltage drop. Then
on top convert that into the 12V. I'd limit to 36 for safety. You might
have to post flags warning of voltage present. Much like cattle fences.

Martin


Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/


grumpyoldhori wrote:
Stephen Robinson wrote:

What is the application and estimated amount of use per day?

Running a Linksys wireless router on a hop for a
microwave link.
The output power is only 100mw. but the router draws
five watts on average to power it's board etc.
Running 24/7.
Looked at solar and running copper wire, both came
to around NZ $600
Which is why I am keen on using the steel wire if
possible.



----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.pronews.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= - Total Privacy via Encryption =---

On Sat, 26 Apr 2008 21:48:45 -0500, "Martin H. Eastburn"
wrote:

Phone companies used to use copper clad steel on poles.

Maybe there is some still hanging or some in the phone yard sitting.

I'd talk to them if the phone or power company has scrap line for
this type of use. Might find so. Might find a few to help string
some of which they provide.

Even a bundle of twisted wire could be used - sets of lines in parallel.

The zinc might not be considered in the estimates either. But it leaches off.


I think myself I'd send AC - 36V at 1/3 the current and voltage drop. Then
on top convert that into the 12V. I'd limit to 36 for safety. You might
have to post flags warning of voltage present. Much like cattle fences.

Martin

That'd work ... but I don't think minimizing voltage drop or
maximizing efficiency is the objective. The objective is to get 12
volts at 0.5 amp at the top of the hill. Ya just need enough push
at the bottom to overcome 4 volts or so of drop in the wire that's
already in place. A regulator at the top takes care of having a bit
more push than necessary, which makes scrounging parts much easier.

grumpyoldhori wrote:
Could I have some advice please.
I need to get a twelve volt, 1/2 amp supply five
hundred metres up a hill.
I do have a fence a metre high made from wooden posts and
seven runs of Num eight (4 mil) galvanised steel
wire.
Is it feasible to use two of these wires to carry twelve
volts that distance ?
Thank you.




No.

Line losses will reduce the voltage at the far end way too low
to use.

That's why we use AC voltage for distribution.

Richard
--
(remove the X to email)

Now just why the HELL do I have to press 1 for English?
John Wayne

Line losses will reduce the voltage at the far end way too low
to use.

That's why we use AC voltage for distribution.

Thomas Edison never did agree with you on this issue.

Karl

Karl Townsend wrote:

Line losses will reduce the voltage at the far end way too low
to use.

That's why we use AC voltage for distribution.


Thomas Edison never did agree with you on this issue.

Karl




YEAHbut - his didn't win.

On Sat, 26 Apr 2008 06:29:29 -0500, the renowned "Karl Townsend"
wrote:


Line losses will reduce the voltage at the far end way too low
to use.

That's why we use AC voltage for distribution.

Thomas Edison never did agree with you on this issue.

Karl


Yup, and HV DC transmission has advantages over AC transmission, and
can contribute to overall system stability.

http://en.wikipedia.org/wiki/HVDC

250km undersea (Sweden to Germany) 450kVDC cable:
http://library.abb.com/GLOBAL/SCOT/SCOT245.NSF/VerityDisplay/A74338323CD88E19C1256E36003FFD7A/$File/Project%20Baltic%20Cable%20450%20kV%20MIND%20subm-.pdf




Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

On Sat, 26 Apr 2008 08:01:08 -0400, Spehro Pefhany wrote:
On Sat, 26 Apr 2008 06:29:29 -0500, the renowned "Karl Townsend" wrote:

Line losses will reduce the voltage at the far end way too low
to use.

That's why we use AC voltage for distribution.

Thomas Edison never did agree with you on this issue.

Yup, and HV DC transmission has advantages over AC transmission, and
can contribute to overall system stability.

http://en.wikipedia.org/wiki/HVDC

250km undersea (Sweden to Germany) 450kVDC cable:
http://library.abb.com/GLOBAL/SCOT/SCOT245.NSF/VerityDisplay/A74338323CD88E19C1256E36003FFD7A/$File/Project%20Baltic%20Cable%20450%20kV%20MIND%20subm-.pdf

The only real advantage to these High Voltage DC Interties is that
the power grids on each end do not have to be in exact synchronization
for the systems to exchange power Normal AC transmission lines
require both ends to be following the same frequency standard.


It has to be several hundred miles before HVDC is cheaper, because
of the cost of building the converter stations at the ends. We have
one of these HVDC lines that terminates in Los Angeles and heads to
the Oregon / Washington State border region to pickup on all the
excess summer hydroelectric capacity in the region. And in the winter
when they use a lot of electric heat and the rivers are running low,
we ship power north.

http://en.wikipedia.org/wiki/Pacific_DC_Intertie

With a HVDC Transmission line they can easily tie two different
regional grids together that are not in lock-step with each other,
since the converter plants at either end slave to their region's own
grid frequency - they can even have a gross mis-match like a 50 Hz
grid at one end and a 60 Hz grid at the other.

-- Bruce --

Bruce L. Bergman wrote:
On Sat, 26 Apr 2008 08:01:08 -0400, Spehro Pefhany wrote:

On Sat, 26 Apr 2008 06:29:29 -0500, the renowned "Karl Townsend" wrote:



Line losses will reduce the voltage at the far end way too low
to use.

That's why we use AC voltage for distribution.

Thomas Edison never did agree with you on this issue.

Yup, and HV DC transmission has advantages over AC transmission, and
can contribute to overall system stability.

http://en.wikipedia.org/wiki/HVDC

250km undersea (Sweden to Germany) 450kVDC cable:
http://library.abb.com/GLOBAL/SCOT/SCOT245.NSF/VerityDisplay/A74338323CD88E19C1256E36003FFD7A/$File/Project%20Baltic%20Cable%20450%20kV%20MIND%20subm-.pdf


The only real advantage to these High Voltage DC Interties is that
the power grids on each end do not have to be in exact synchronization
for the systems to exchange power Normal AC transmission lines
require both ends to be following the same frequency standard.


Also the peak voltage equals the average voltage witch reduces the
insulation losses. And the capacity caused current is zero. Therefor the
DC line is more efficiency. But the terminal equipment is expensive

Bill K7NOM
It has to be several hundred miles before HVDC is cheaper, because
of the cost of building the converter stations at the ends. We have
one of these HVDC lines that terminates in Los Angeles and heads to
the Oregon / Washington State border region to pickup on all the
excess summer hydroelectric capacity in the region. And in the winter
when they use a lot of electric heat and the rivers are running low,
we ship power north.

http://en.wikipedia.org/wiki/Pacific_DC_Intertie

With a HVDC Transmission line they can easily tie two different
regional grids together that are not in lock-step with each other,
since the converter plants at either end slave to their region's own
grid frequency - they can even have a gross mis-match like a 50 Hz
grid at one end and a 60 Hz grid at the other.

-- Bruce --

On Sat, 26 Apr 2008 06:29:29 -0500, with neither quill nor qualm,
"Karl Townsend" quickly quoth:


Line losses will reduce the voltage at the far end way too low
to use.

That's why we use AC voltage for distribution.

Thomas Edison never did agree with you on this issue.

No, but Westinghouse, using Uncle Nikola's technology, became the
defacto standard around the world in no time at all. Uncle Tom,
clinging tightly to Uncle Ben's technology, missed the boat on that
one entirely. He lost a ****load of cash on that horserace, wot?

--
Happiness in marriage is entirely a matter of chance. If the dispositions
of the parties are ever so well known to each other or ever so similar
beforehand, it does not advance their felicity in the least. They always
continue to grow sufficiently unlike afterwards to have their share of
vexation; and it is better to know as little as possible of the defects of
the person with whom you are to pass your life.
-- Jane Austen, Pride and Prejudice, 1811

Karl Townsend wrote:
Line losses will reduce the voltage at the far end way too low
to use.

That's why we use AC voltage for distribution.


Thomas Edison never did agree with you on this issue.
And, that's why he planned power plants even closer than the
OP's need of 500 M transmission. With proper insulators and
elevating the wire above people's reach, it would make the most
sense to sent the 230 V to the remote location, but the wire is
already where it is.

Jon

Karl Townsend wrote:

Line losses will reduce the voltage at the far end way too low
to use.

That's why we use AC voltage for distribution.

Thomas Edison never did agree with you on this issue.


That was because he wanted to own a DC power plant every two miles.


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http://improve-usenet.org/index.html


Use any search engine other than Google till they stop polluting USENET
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On Sat, 26 Apr 2008 01:44:38 -0500, cavelamb himself
wrote:

grumpyoldhori wrote:
Could I have some advice please.
I need to get a twelve volt, 1/2 amp supply five
hundred metres up a hill.
I do have a fence a metre high made from wooden posts and
seven runs of Num eight (4 mil) galvanised steel
wire.
Is it feasible to use two of these wires to carry twelve
volts that distance ?
Thank you.




No.

Line losses will reduce the voltage at the far end way too low
to use.

That's why we use AC voltage for distribution.

Richard

Yeah, sorta. AC actually has more line loss than DC, though the
difference would be unmeasurable at this distance and power level. AC
is used for distribution because (AC) transformers can change voltage
efficiently. High voltage power distribution results in lower line
current hence lower line loss for given size wire.

In this situation, all that's needed is enough excess voltage at the
sending end to make up for about 4 volts of line drop at 0.5 amp. A
simple regulator at the load end makes it possible to use any DC
source (18 to 24 VDC at 0.5 amp) that's readily available.

One could also use a transformer at the sending end, AC on the wires,
rectify and regulate at the load end. Doesn't matter, use whatever's
easy and readily available.

Ping Andrew in Oz (VK3BFA) for possible sources of supplies.

grumpyoldhori wrote:

* Could I have some advice please.
* I need to get a twelve volt, 1/2 amp supply five
hundred metres up a hill.
I do have a fence a metre high made from wooden posts and
seven runs of Num eight (4 mil) galvanised steel
wire.
Is it feasible to use two of these wires to carry twelve
volts that distance ?
Thank you.
*

Well most likely. Your steel wire has a higher ohms per foot than copper
wire so the drop across the wire may be significant.

http://en.wikipedia.org/wiki/Resistivity

Resistivity (?-m) at 20 °C
Copper 1.72×10-8
Iron 1.0×10-7

I couldn't make sense of the units but basically it looks like steel wire is
17.2x worse a conductor than steel, so you now have a 8600 meter copper
equivalent run.

http://www.eskimo.com/~billb/tesla/wire1.txt

For copper, 0.6282 ohms per 1K feet. 8600 meter = ~28K feet, which yields
17.6 ohms per strand or 35.2 ohms for the circuit.

Now assuming your end load needs .5 amp you have a series circuit where a
certain amount of voltage will be dropped across the fence. Right off the
bat, that 12V input isn't going to be what you want.

Now your end load is 24 ohms, 6 watts assuming it needs all .5 amps. If the
load is variable, well it gets messy. So assuming you need all .5 amps you
have 24 ohms + 35.2 ohms in your series circuit. Right off the bat, it
looks like 12v in isn't going to work and 24 isn't enough either.

So if you drop 12v across 24 ohms, you will have to drop 35.2/24 * 12v
across the wire if my grasp of this is right. I've have a beer or two since
it is the weekend so my thinking might be faulty

E=IR
E=.5 x 59.2
E= 29.6

Not sure I didn't blow something but it looks reasonable to me atm.

NN

Wes

So 17.6 volts across the circuit. That makes 17.6 + 12v = 29.6v
P=IE
I = P/E
I = .5 / 29.6v

So yes this is doable, you just need to feed in a higher voltage to get what
you need at the end. I'm not sure how legal putting 30V out on a fence is
in your jurisdiction though.

Wes

--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

Wes wrote:

So yes this is doable, you just need to feed in a higher voltage to get
what you need at the end. Â*I'm not sure how legal putting 30V out on a
fence is in your jurisdiction though.


Great, thanks for that, I am in New Zealand, trying to get
internet access to a couple of isolated homes.
It is a volunteer job and they not not have the money for
the four solar setups needed.

Of course we do have a lot of fences available to hold all
the sheep in.
I will have to check the legality, but I cannot see thirty
volts DC being a problem.

"grumpyoldhori" wrote in message
...
Wes wrote:

So yes this is doable, you just need to feed in a higher voltage to get
what you need at the end. I'm not sure how legal putting 30V out on a
fence is in your jurisdiction though.


Great, thanks for that, I am in New Zealand, trying to get
internet access to a couple of isolated homes.
It is a volunteer job and they not not have the money for
the four solar setups needed.

Of course we do have a lot of fences available to hold all
the sheep in.
I will have to check the legality, but I cannot see thirty
volts DC being a problem.

I wonder what the earth resistance is like? Potentially you could use all
seven strands up, and the earth as a return. That also gives you plenty of
redundancy if you lose a strand (but you have to keep them all insulated).
As others have said, I would go for AC with a decent isolation system at the
top end to protect the router against lightning.

In article ,
grumpyoldhori wrote:

Wes wrote:

So yes this is doable, you just need to feed in a higher voltage to get
what you need at the end. Â*I'm not sure how legal putting 30V out on a
fence is in your jurisdiction though.


Great, thanks for that, I am in New Zealand, trying to get
internet access to a couple of isolated homes.
It is a volunteer job and they not not have the money for
the four solar setups needed.

Of course we do have a lot of fences available to hold all
the sheep in.
I will have to check the legality, but I cannot see thirty
volts DC being a problem.

Telephone systems run at 50 volts, and cause no particular safety
problem. Likewise, power over ethernet uses ~50 volts.

In the US, the electrical code allows up to ~50 volt systems to be
handled far more simply than power systems. It think that this rule is
true worldwide.

So, the simplest system is two AC transformers, one to take the voltage
down from 220 to about 48 volts, and another to take the voltage back up
to 110 or 220 for the router, with three steel wire strands carrying one
side of the 48-volt and three strands carrying the other side. The
seventh strand is grounded and hooked to the center taps of the 48-volt
windings, so the max voltage to ground is 24 volts.

You may need insulators to prevent outages during rainstorms.

You will need lightning protectors and individual fuses on both ends of
both sets of 3 strands, for a total of four fuses and four lightning
protectors. The ground strand should be grounded at both ends.

The 48 volts will help the cows to remember to not scratch on the fence.

Joe Gwinn

"Joseph Gwinn" wrote in message
...
In article ,
grumpyoldhori wrote:

Wes wrote:

So yes this is doable, you just need to feed in a higher voltage to get
what you need at the end. Â I'm not sure how legal putting 30V out on a
fence is in your jurisdiction though.


Great, thanks for that, I am in New Zealand, trying to get
internet access to a couple of isolated homes.
It is a volunteer job and they not not have the money for
the four solar setups needed.

Of course we do have a lot of fences available to hold all
the sheep in.
I will have to check the legality, but I cannot see thirty
volts DC being a problem.

Telephone systems run at 50 volts, and cause no particular safety
problem. Likewise, power over ethernet uses ~50 volts.

In the US, the electrical code allows up to ~50 volt systems to be
handled far more simply than power systems. It think that this rule is
true worldwide.

So, the simplest system is two AC transformers, one to take the voltage
down from 220 to about 48 volts, and another to take the voltage back up
to 110 or 220 for the router, with three steel wire strands carrying one
side of the 48-volt and three strands carrying the other side. The
seventh strand is grounded and hooked to the center taps of the 48-volt
windings, so the max voltage to ground is 24 volts.

You may need insulators to prevent outages during rainstorms.

You will need lightning protectors and individual fuses on both ends of
both sets of 3 strands, for a total of four fuses and four lightning
protectors. The ground strand should be grounded at both ends.

The 48 volts will help the cows to remember to not scratch on the fence.

Joe Gwinn

This is the best advice yet. The higher the voltage you run, the lower the
current and lower the voltage drop. Can you find 220 to 48 volt
transformers? Pay close attention to the use of transient protection. Even
so, you will more than likely loose a few routers.

On Apr 26, 10:03*am, "Tom M" wrote:
...
So, the simplest system is two AC transformers, one to take the voltage
down from 220 to about 48 volts, and another to take the voltage back up
to 110 or 220 for the router, with three steel wire strands carrying one
side of the 48-volt and three strands carrying the other side. *The
seventh strand is grounded and hooked to the center taps of the 48-volt
windings, so the max voltage to ground is 24 volts.

You may need insulators to prevent outages during rainstorms.

You will need lightning protectors and individual fuses on both ends of
both sets of 3 strands, for a total of four fuses and four lightning
protectors. *The ground strand should be grounded at both ends.
...
This is the best advice yet. The higher the voltage you run, the lower the
current and lower the voltage drop. Can you find 220 to 48 volt
transformers? Pay close attention to the use of transient protection. Even
so, you will more than likely loose a few routers.

If you can find the parts cheap, you could turn whatever is left of
the 48VAC to 24VAC with a 2:1 transformer, a 120:240 one would be
fine, rectify it and charge a used 12V car battery. If the charging
current is too much you could limit it with a light bulb in series.
They are pretty close to being constant current regulators.

Joseph Gwinn wrote:

In article ,
grumpyoldhori wrote:

Wes wrote:

So yes this is doable, you just need to feed in a higher voltage to get
what you need at the end. Â I'm not sure how legal putting 30V out on a
fence is in your jurisdiction though.


Great, thanks for that, I am in New Zealand, trying to get
internet access to a couple of isolated homes.
It is a volunteer job and they not not have the money for
the four solar setups needed.

Of course we do have a lot of fences available to hold all
the sheep in.
I will have to check the legality, but I cannot see thirty
volts DC being a problem.

Telephone systems run at 50 volts, and cause no particular safety
problem. Likewise, power over ethernet uses ~50 volts.

Telephones are DC, not AC.


In the US, the electrical code allows up to ~50 volt systems to be
handled far more simply than power systems. It think that this rule is
true worldwide.

So, the simplest system is two AC transformers, one to take the voltage
down from 220 to about 48 volts, and another to take the voltage back up
to 110 or 220 for the router, with three steel wire strands carrying one
side of the 48-volt and three strands carrying the other side. The
seventh strand is grounded and hooked to the center taps of the 48-volt
windings, so the max voltage to ground is 24 volts.


I don't know about NZ but in the US, anything ove 24 VAC has to be
treated as class 1 wiring, the same as 120 and 240 VAC. 48 VAC is 67.872
peak. If you run into it with damp or wet skin with that availible
current, it could kill someone.


You may need insulators to prevent outages during rainstorms.

You will need lightning protectors and individual fuses on both ends of
both sets of 3 strands, for a total of four fuses and four lightning
protectors. The ground strand should be grounded at both ends.

The 48 volts will help the cows to remember to not scratch on the fence.

Joe Gwinn


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Use any search engine other than Google till they stop polluting USENET
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"Michael A. Terrell" wrote:

Telephones are DC, not AC.

Except for the ringing. IIRC, 50,60,70 hz were used to ring the bell on
party line phones.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

Telephone systems run at 50 volts, and cause no particular safety
problem. Likewise, power over ethernet uses ~50 volts.

In the US, the electrical code allows up to ~50 volt systems to be
handled far more simply than power systems. It think that this rule is
true worldwide.

Joe, that is not for ground level un-insulated wire is it?