Post by thread:[EE]:: SWER - Single Wire Earth Return power trans

BCC: JMC - Any of these in Vanuatu? 1st reference is useful in spelling out the basic factors of concern when designing an earth return power system. Thee is a little more magic to it than may meet the eye. Not something most people are liable to do very often. But ... SWER = Single Wire Earth Return power transmission is essentially just that. A single high voltage (say 10 kV to 30 kV) phase wire is used to distribute power and the return circuit uses ground. While this at first and second blances may sound like very old technology (and it is) it is also still of great use in niche applications. Medium length rural distributions of moderate power requirement may still be most cost effectively served by SWER. I'm posting this mainly because of the excellent material in the first link below. http://www.stonepower.se/Images/SWER.pdf Distribution of Electrical Power to Rural Areas- Australian Experience and Implementation Possibility in Developing Countries http://www.iranenergy.org.ir/library/articles/5%20articles%20national%20energy%20congress/pdf/1406.pdf Wikipedia http://en.wikipedia.org/wiki/Single_wire_earth_return Sci,Eng http://groups.google.com/group/sci.engr.electrical.sys-protection/browse_thread/thread/5013cb01d9526811/3539d5ffb9062da4%3Fq%3D%2522High%2BVoltage%2522%233539d5ffb9062da4&ei=iGwTS6eaOpW8Qpmqic0O&sa=t&ct=res&cd=2&source=groups&usg=AFQjCNFy3KmggWtXV7X5hmiPPWIADmQw1g?pli=1 ________________________________ This amused me, as an example test for the TECH / EE boundary is things you cannot/can build at home and a power station is mentioned as something that you (notionally) can't. . This is connected to a power station and is on the large side of DIY but the expressions given may indeed assist some DIY endeavours. Russell McMahon

It is used extensively in Brazil for small rural properties. What annoys me is that most of Brazil uses 220V/380 3-phase but for rural SWER the power companies only allow installation of bi-phase 127V+127V. That's very bad, because I need to buy 127V lamps in a state that is primarily 220V and my 220V electric tools must be connected to phase-phase 254V (15% more voltage, 33% power overload) risking damage. Isaac Em 16/4/2012 11:10, RussellMc escreveu: {Quote hidden}> BCC: JMC - Any of these in Vanuatu? > > 1st reference is useful in spelling out the basic factors of concern > when designing an earth return power system. > Thee is a little more magic to it than may meet the eye. > Not something most people are liable to do very often. But ... > > SWER = Single Wire Earth Return power transmission is essentially just > that. A single high voltage (say 10 kV to 30 kV) phase wire is used to > distribute power and the return circuit uses ground. While this at > first and second blances may sound like very old technology (and it > is) it is also still of great use in niche applications. Medium length > rural distributions of moderate power requirement may still be most > cost effectively served by SWER. > > I'm posting this mainly because of the excellent material in the first > link below. > > http://www.stonepower.se/Images/SWER.pdf > > > Distribution of Electrical Power to Rural Areas- > Australian Experience and Implementation > Possibility in Developing Countries > http://www.iranenergy.org.ir/library/articles/5%20articles%20national%20energy%20congress/pdf/1406.pdf > > > Wikipedia > http://en.wikipedia.org/wiki/Single_wire_earth_return > > > Sci,Eng > http://groups.google.com/group/sci.engr.electrical.sys-protection/browse_thread/thread/5013cb01d9526811/3539d5ffb9062da4%3Fq%3D%2522High%2BVoltage%2522%233539d5ffb9062da4&ei=iGwTS6eaOpW8Qpmqic0O&sa=t&ct=res&cd=2&source=groups&usg=AFQjCNFy3KmggWtXV7X5hmiPPWIADmQw1g?pli=1 > > > ________________________________ > > This amused me, as an example test for the TECH / EE boundary is > things you cannot/can build at home and a power station is mentioned > as something that you (notionally) can't. . This is connected to a > power station and is on the large side of DIY but the expressions > given may indeed assist some DIY endeavours. > > > > > Russell McMahon >

Won't the return currents cause ionization in the terrain, etc.. possibily with biological implications? At 16.10 2012.04.16, you wrote: {Quote hidden}> BCC: JMC - Any of these in Vanuatu? > >1st reference is useful in spelling out the basic factors of concern >when designing an earth return power system. >Thee is a little more magic to it than may meet the eye. >Not something most people are liable to do very often. But ... > >SWER = Single Wire Earth Return power transmission is essentially just >that. A single high voltage (say 10 kV to 30 kV) phase wire is used to >distribute power and the return circuit uses ground. While this at >first and second blances may sound like very old technology (and it >is) it is also still of great use in niche applications. Medium length >rural distributions of moderate power requirement may still be most >cost effectively served by SWER. > >I'm posting this mainly because of the excellent material in the first >link below. > >http://www.stonepower.se/Images/SWER.pdf > > >Distribution of Electrical Power to Rural Areas- >Australian Experience and Implementation >Possibility in Developing Countries >www.iranenergy.org.ir/library/articles/5%20articles%20national% >20energy%20congress/pdf/1406.pdf > > >Wikipedia >http://en.wikipedia.org/wiki/Single_wire_earth_return > > >Sci,Eng >groups.google.com/group/sci.engr.electrical.sys-protection/brow >se_thread/thread/5013cb01d9526811/3539d5ffb9062da4%3Fq%3D%2522High%2BV >oltage%2522%233539d5ffb9062da4&ei=iGwTS6eaOpW8Qpmqic0O&sa=t&ct=res&cd= >2&source=groups&usg=AFQjCNFy3KmggWtXV7X5hmiPPWIADmQw1g?pli=1 > > >________________________________ > >This amused me, as an example test for the TECH / EE boundary is >things you cannot/can build at home and a power station is mentioned >as something that you (notionally) can't. . This is connected to a >power station and is on the large side of DIY but the expressions >given may indeed assist some DIY endeavours. > > > > > Russell McMahon > >

If I remember it right, the majority of return currents flow at 300 to 400 meters below ground. Isaac Em 20/4/2012 02:07, Electron escreveu: {Quote hidden}> Won't the return currents cause ionization in the terrain, etc.. possibily > with biological implications? > > > At 16.10 2012.04.16, you wrote: >> BCC: JMC - Any of these in Vanuatu? >> >> 1st reference is useful in spelling out the basic factors of concern >> when designing an earth return power system. >> Thee is a little more magic to it than may meet the eye. >> Not something most people are liable to do very often. But ... >> >> SWER = Single Wire Earth Return power transmission is essentially just >> that. A single high voltage (say 10 kV to 30 kV) phase wire is used to >> distribute power and the return circuit uses ground. While this at >> first and second blances may sound like very old technology (and it >> is) it is also still of great use in niche applications. Medium length >> rural distributions of moderate power requirement may still be most >> cost effectively served by SWER. >> >> I'm posting this mainly because of the excellent material in the first >> link below. >> >> http://www.stonepower.se/Images/SWER.pdf >> >> >> Distribution of Electrical Power to Rural Areas- >> Australian Experience and Implementation >> Possibility in Developing Countries >> www.iranenergy.org.ir/library/articles/5%20articles%20national% >> 20energy%20congress/pdf/1406.pdf >> >> >> Wikipedia >> en.wikipedia.org/wiki/Single_wire_earth_return >> >> >> Sci,Eng >> groups.google.com/group/sci.engr.electrical.sys-protection/brow >> se_thread/thread/5013cb01d9526811/3539d5ffb9062da4%3Fq%3D%2522High%2BV >> oltage%2522%233539d5ffb9062da4&ei=iGwTS6eaOpW8Qpmqic0O&sa=t&ct=res&cd= >> 2&source=groups&usg=AFQjCNFy3KmggWtXV7X5hmiPPWIADmQw1g?pli=1 >> >> >> ________________________________ >> >> This amused me, as an example test for the TECH / EE boundary is >> things you cannot/can build at home and a power station is mentioned >> as something that you (notionally) can't. . This is connected to a >> power station and is on the large side of DIY but the expressions >> given may indeed assist some DIY endeavours. >> >> >> >> >> Russell McMahon >> >> --

On 5/3/2012 3:27 PM, Martin McCormick wrote: > Electron writes: >> Won't the return currents cause ionization in the terrain, etc.. possibily >> with biological implications? > I just red the pdf on the link and it did say that the > return currents were around 1200 meters down. I know that > alternating current is successfully used in meggers which are > magneto-based ohm meters for measuring soil conductivity. I > don't know what would happen over a long period of current flow > but as long as there is not a DC component, the continuous > reversal seems to prevent ionization. > > Neon and fluorescent lamps last much longer running on > AC than they do on DC. Also, some en clinometers use an > electrolyte in a sealed tube and they can be damaged by DC but > work fine on AC. > > Martin McCormick > WB5AGZ I also read the PDF thoroughly. I am inclined to consider the idea of transmitting power through ground as unsound. I see that, in theory, current will pass through the ground. But will it do so reliably? Wouldn't the fact that soil holds a varying amount of moisture cause a differing amount of conductivity? Wouldn't two metal poles placed in the ground 3' deep and 50' apart measure a very different conductivity at night vs during the day, because of the daytime evaporation of surface soil water? Who says that the current flows deep under the ground (i.e., 1200m)? Why doesn't it take the path of least resistance, like current normally does (I've never seen it do otherwise in my entire life)? This conversation is interesting because it MIGHT eliminate the need for a single wire. Otherwise, it is starting to sound like the study of bumps on the head being related to intelligence, or mankind causing global warming with automobiles or cows passing gas. --Bo

When measuring ground return for payphone metering in Aust (metering no longer uses ground return) i was surprised to discover measurement less than 50 ohms over km's The only way i could explain away the low readings was to consider the ground as many conductors in parallel. .. On 04/05/2012, Bob Axtell <spam_OUTbob.axtellTakeThisOuTgmail.com> wrote: {Quote hidden}> On 5/3/2012 3:27 PM, Martin McCormick wrote: >> Electron writes: >>> Won't the return currents cause ionization in the terrain, etc.. >>> possibily >>> with biological implications? >> I just red the pdf on the link and it did say that the >> return currents were around 1200 meters down. I know that >> alternating current is successfully used in meggers which are >> magneto-based ohm meters for measuring soil conductivity. I >> don't know what would happen over a long period of current flow >> but as long as there is not a DC component, the continuous >> reversal seems to prevent ionization. >> >> Neon and fluorescent lamps last much longer running on >> AC than they do on DC. Also, some en clinometers use an >> electrolyte in a sealed tube and they can be damaged by DC but >> work fine on AC. >> >> Martin McCormick >> WB5AGZ > I also read the PDF thoroughly. I am inclined to consider the idea of > transmitting > power through ground as unsound. > > I see that, in theory, current will pass through the ground. But will it > do so reliably? > Wouldn't the fact that soil holds a varying amount of moisture cause a > differing > amount of conductivity? Wouldn't two metal poles placed in the ground 3' > deep > and 50' apart measure a very different conductivity at night vs during > the day, > because of the daytime evaporation of surface soil water? > > Who says that the current flows deep under the ground (i.e., 1200m)? Why > doesn't > it take the path of least resistance, like current normally does (I've > never seen it do > otherwise in my entire life)? > > > > This conversation is interesting because it MIGHT eliminate the need for > a single > wire. Otherwise, it is starting to sound like the study of bumps on the > head being > related to intelligence, or mankind causing global warming with > automobiles or > cows passing gas. > > --Bob >

the spec was < 50 ohms but the actual readings were less than 15 ohms if memory serves On 04/05/2012, Justin Richards <.....justin.richardsKILLspam@spam@gmail.com> wrote: {Quote hidden}> When measuring ground return for payphone metering in Aust (metering > no longer uses ground return) i was surprised to discover measurement > less than 50 ohms over km's > > The only way i could explain away the low readings was to consider the > ground as many conductors in parallel. > > . > > > > > > On 04/05/2012, Bob Axtell <bob.axtellKILLspamgmail.com> wrote: >> On 5/3/2012 3:27 PM, Martin McCormick wrote: >>> Electron writes: >>>> Won't the return currents cause ionization in the terrain, etc.. >>>> possibily >>>> with biological implications? >>> I just red the pdf on the link and it did say that the >>> return currents were around 1200 meters down. I know that >>> alternating current is successfully used in meggers which are >>> magneto-based ohm meters for measuring soil conductivity. I >>> don't know what would happen over a long period of current flow >>> but as long as there is not a DC component, the continuous >>> reversal seems to prevent ionization. >>> >>> Neon and fluorescent lamps last much longer running on >>> AC than they do on DC. Also, some en clinometers use an >>> electrolyte in a sealed tube and they can be damaged by DC but >>> work fine on AC. >>> >>> Martin McCormick >>> WB5AGZ >> I also read the PDF thoroughly. I am inclined to consider the idea of >> transmitting >> power through ground as unsound. >> >> I see that, in theory, current will pass through the ground. But will it >> do so reliably? >> Wouldn't the fact that soil holds a varying amount of moisture cause a >> differing >> amount of conductivity? Wouldn't two metal poles placed in the ground 3' >> deep >> and 50' apart measure a very different conductivity at night vs during >> the day, >> because of the daytime evaporation of surface soil water? >> >> Who says that the current flows deep under the ground (i.e., 1200m)? Why >> doesn't >> it take the path of least resistance, like current normally does (I've >> never seen it do >> otherwise in my entire life)? >> >> >> >> This conversation is interesting because it MIGHT eliminate the need for >> a single >> wire. Otherwise, it is starting to sound like the study of bumps on the >> head being >> related to intelligence, or mankind causing global warming with >> automobiles or >> cows passing gas. >> >> --Bob >> -

Em 4/5/2012 11:24, Bob Axtell escreveu: {Quote hidden}> On 5/3/2012 3:27 PM, Martin McCormick wrote: >> Electron writes: >>> Won't the return currents cause ionization in the terrain, etc.. possibily >>> with biological implications? >> I just red the pdf on the link and it did say that the >> return currents were around 1200 meters down. I know that >> alternating current is successfully used in meggers which are >> magneto-based ohm meters for measuring soil conductivity. I >> don't know what would happen over a long period of current flow >> but as long as there is not a DC component, the continuous >> reversal seems to prevent ionization. >> >> Neon and fluorescent lamps last much longer running on >> AC than they do on DC. Also, some en clinometers use an >> electrolyte in a sealed tube and they can be damaged by DC but >> work fine on AC. >> >> Martin McCormick >> WB5AGZ > I also read the PDF thoroughly. I am inclined to consider the idea of > transmitting > power through ground as unsound. > > I see that, in theory, current will pass through the ground. But will it > do so reliably? > Wouldn't the fact that soil holds a varying amount of moisture cause a > differing > amount of conductivity? Wouldn't two metal poles placed in the ground 3' > deep > and 50' apart measure a very different conductivity at night vs during > the day, > because of the daytime evaporation of surface soil water? > > Who says that the current flows deep under the ground (i.e., 1200m)? Why > doesn't > it take the path of least resistance, like current normally does (I've > never seen it do > otherwise in my entire life)? Why could not at 1200m deep the conductivity be maximal? Perhaps rocks full of metal ore, soaked in water? Isaac

"What have you done with Bob " asked about reality and practicality of SWER power lines. __________ "SWER" power lines have a very long history and are highly useful. They still have some very competent protagonists and a significant number are still in use. Engineers will be aware of the two dimensional concept of "Ohms per square". If a 1 cm edge square of a given thickness of a uniform resistive sheet has a given resistance between opposite parallel sides, then a 1 metre edge square or a 100m edge square of the same thickness of identical material will have the same resistance edge to edge as has the 1cm edge square. This is obvious on inspection as increasing the dimensions scales up the path length and path width in equal ratio. The resistance of "ground" behaves similarly - here we are coupling into a half sphere about the end points and we must deal with 3D curvilinear cubes (rather that the more familiar 2D curvilinear squares) but the end result is similar. The main issue in connecting a high energy ground path between two points some km apart is coupling into the bulk ground at each end - the resistance of "the earth" is not a problem - attaching to it is. As Bob adumbrates, it is possible to make ground connections whose quality varies widely with local conditions - BUT 'we' have centiries of experience of creating reliable repeatable ground connections. All electric power administrations have procedures which are required to b followed to produce an adequate ground connection for a given taks under worst case conditions. The procedure do indeed superficially appear somewhat similar to phrenology but the comparison is illusory. Here the bumps on a head are replaced by soil types, water table, length and diameter and material of of grounding pipes, sacks of Bentonite, and more. The ground protection systems in Phase / Neutral / Safety ground systems in widespread use in many countries depends crucially on the ability to make and maintain an adequate safety grounds. The UK and NZ are two such - it seems 'from a distance' tat US practice may be less stringent with some systems. > Who says that the current flows deep under the ground (i.e., 1200m)? > Why doesn't it take the path of least resistance, like current normally does > (I've never seen it do otherwise in my entire life)? Here as in all systems, current flows in proportion to the applied voltage and inversely in proportion to the resistance the voltage is applied over. ie current does not take the path of least resistance but "takes the paths of all resistances" - from each according to its inverse resistance, to each according to its applied voltage. But, I know that you know that. The claim that current flow ***mainly*** at a depth of 200 feet is quite possibly correct and if it is, is liable to be caused by non linear compositions of real world strata and soil conditions forming a path of effective minimal resistance for power currents. material will certain On 5 May 2012 02:24, Bob Axtell <.....bob.axtellKILLspam.....gmail.com> wrote: {Quote hidden}> On 5/3/2012 3:27 PM, Martin McCormick wrote: > > Electron writes: > >> Won't the return currents cause ionization in the terrain, etc.. > possibily > >> with biological implications? > > I just red the pdf on the link and it did say that the > > return currents were around 1200 meters down. I know that > > alternating current is successfully used in meggers which are > > magneto-based ohm meters for measuring soil conductivity. I > > don't know what would happen over a long period of current flow > > but as long as there is not a DC component, the continuous > > reversal seems to prevent ionization. > > > > Neon and fluorescent lamps last much longer running on > > AC than they do on DC. Also, some en clinometers use an > > electrolyte in a sealed tube and they can be damaged by DC but > > work fine on AC. > > > > Martin McCormick > > WB5AGZ > I also read the PDF thoroughly. I am inclined to consider the idea of > transmitting > power through ground as unsound. > > I see that, in theory, current will pass through the ground. But will it > do so reliably? > Wouldn't the fact that soil holds a varying amount of moisture cause a > differing > amount of conductivity? Wouldn't two metal poles placed in the ground 3' > deep > and 50' apart measure a very different conductivity at night vs during > the day, > because of the daytime evaporation of surface soil water? > > Who says that the current flows deep under the ground (i.e., 1200m)? Why > doesn't > it take the path of least resistance, like current normally does (I've > never seen it do > otherwise in my entire life)? > > > > This conversation is interesting because it MIGHT eliminate the need for > a single > wire. Otherwise, it is starting to sound like the study of bumps on the > head being > related to intelligence, or mankind causing global warming with > automobiles or > cows passing gas. > > --Bob >

Current takes all possible paths. It prefers the path of least impedance. Isaac Marino Bavaresco <EraseMEisaacbavarescospam_OUTTakeThisOuTyahoo.com.br> wrote: {Quote hidden}>Em 4/5/2012 11:24, Bob Axtell escreveu: >> On 5/3/2012 3:27 PM, Martin McCormick wrote: >>> Electron writes: >>>> Won't the return currents cause ionization in the terrain, etc.. possibily >>>> with biological implications? >>> I just red the pdf on the link and it did say that the >>> return currents were around 1200 meters down. I know that >>> alternating current is successfully used in meggers which are >>> magneto-based ohm meters for measuring soil conductivity. I >>> don't know what would happen over a long period of current flow >>> but as long as there is not a DC component, the continuous >>> reversal seems to prevent ionization. >>> >>> Neon and fluorescent lamps last much longer running on >>> AC than they do on DC. Also, some en clinometers use an >>> electrolyte in a sealed tube and they can be damaged by DC but >>> work fine on AC. >>> >>> Martin McCormick >>> WB5AGZ >> I also read the PDF thoroughly. I am inclined to consider the idea of >> transmitting >> power through ground as unsound. >> >> I see that, in theory, current will pass through the ground. But will it >> do so reliably? >> Wouldn't the fact that soil holds a varying amount of moisture cause a >> differing >> amount of conductivity? Wouldn't two metal poles placed in the ground 3' >> deep >> and 50' apart measure a very different conductivity at night vs during >> the day, >> because of the daytime evaporation of surface soil water? >> >> Who says that the current flows deep under the ground (i.e., 1200m)? Why >> doesn't >> it take the path of least resistance, like current normally does (I've >> never seen it do >> otherwise in my entire life)? > > >Why could not at 1200m deep the conductivity be maximal? Perhaps rocks >full of metal ore, soaked in water? > > >Isaac > > >

Justin Richards wrote: > The only way i could explain away the low readings was to consider the > ground as many conductors in parallel. > Right. Let us consider a simplified case Imagine a hemisphere of radius R made of a perfect conductor burried with the flat of the hemisphere level with the surface in infinitely extending ground of constant resistivity p with an atmosphere of infinitie resistivity above it. Now let us consider the soil round the hemisphere we can divide this soil into an infinite number of infinitesimally thin hemispherical shells of infinite resistivity. These hemispheres have a diameter of r and a thickness of dr The shell has an area of 2Ï€rÂ² and a thickness of dr so it's resistance is p/(2Ï€rÂ²) dr To cover all the shells now we integrate from r=R to r=âˆž So our resistance becomes (-(p/(2Ï€âˆž))) - (-(p/(2Ï€R))) which simplifies to. p/(2Ï€R) In other words the resistance "to infinity" is a finite number! While this is a simplified case the general principle holds for real grounding, the issue is the resistance of the layers of material close to your connections, far from your connections the area is so great that the resistance becomes negligable.

Interesting discussion, as always. Also four days late, as always. I think if you trust the assertion of the resistance at several hundred meters down, then the problem becomes assuring that your ground posts "get connected to" the "underground expressway". This isn't likely to happen at 50' separation, but at powerline company distances, it will. As to that unfortunate folklore about the path of least resistance, If I apply 10 volts across a 100 ohm resistor, paralleled with a 25 ohm resistor, I simply calculate the current for the 25 and ignore the 100 :) <-- don't miss the smiley :) On Fri, May 4, 2012 at 7:24 AM, Bob Axtell <bob.axtellspam_OUTgmail.com> wrote: {Quote hidden}> > I am inclined to consider the idea of transmitting power through ground as > unsound. > > I see that, in theory, current will pass through the ground. But will it > do so reliably? > Wouldn't the fact that soil holds a varying amount of moisture cause a > differing > amount of conductivity? Wouldn't two metal poles placed in the ground 3' > deep > and 50' apart measure a very different conductivity at night vs duringthe > day, > because of the daytime evaporation of surface soil water? > > Who says that the current flows deep under the ground (i.e., 1200m)? Why > doesn't > it take the path of least resistance, like current normally does (I've > never seen it do otherwise in my entire life)?