Single Wire Earth Return

[Archimedes' Lever]

He should try that new clinic run by Smith 7 Wesson. The results are
both affordable, & 100% effective.

No such company, you total retard.

 

[[email protected]]

Especially since I wouldn't go to a psychiatrist if you paid me. You
lose, again, keithtardstaintard.

I lose? Everyone around you loses. Nope, AlwaysWrong, I'm plenty far away
from your hell-hole.

 

[bud--]

I did a little research as I was not familiar with this term and was amazed
that farmers would even try this, based on my experiences at the company I
used to work at. Using the earth as a neutral, particularly in Canada or
the northern US where the soil conditions can change dramatically over the
course of the year is foolhardy and dangerous. Protection systems,
particularly GFI would not work correctly if at all. The farm animals,
being 4 legged, are more susceptible to step potential than we are. In a
fault condition that step voltage could get quite high.

The research I did came up with a paper written back in 1947 for New
Zealand, and a WEB site titled "RuralPower.org" which advocates it but seems
directed towards countries like India and Nigeria.

--

\\\|///
[ @ @ ]
.........o00o..(_)..o00o.........

Cheers .,. Bob
PEng Retired

What does cause quite a few of
those problems is the inadequacy of the neutral in MGM utility systems
for maintaining a low impedance return path for the High voltage
currents in the utilities distribution systems back to their point of
origin at the substation transformer. As the neutral return path
impedance rises the flow of current through the earth from utility MGN
grounds back to the substation grounds and thence to the source at the
substation transformer also increases. As the current flows through
the earth increases so does the voltage across the surface of the
earth through which that current is flowing. It is that increasing
step potential that causes the health and behavioral changes in live
stock.

I would think a wired neutral would be pretty reliable and a much lower
impedance than earth return. What problems do you get?

There will be Concrete encased electrodes at each newer
farm building that has a concrete foundation or footing. There will
be a genuine Ufer grounding array in the floor of any recently rebuilt
milking parlor.

If you have the floor mesh bonded to building ground, and entrance ramps
constructed so there is not step potential from ramp to dirt is there
still a problem? (Like animals in the yard?) I have read almost nothing
on stray voltage.

There are some utilities, most often consumer owned rural
electrification cooperatives, that have addressed these problems
successfully. Some have installed special transformers that provide a
high impedance on the connection to the customers neutral. Having not
had the opportunity to examine one up close I have no idea how they
accomplish that. Others have resorted to providing isolating
transformers at dairy farms in place of the regular pole pig.

If the supply is MGN, both of these are just not connecting the
secondary neutral to the primary ground return?

Interesting post.


To the original question, I thought SWER/MGN was commonly used in the
original US rural electrification - REA (starting about 1935). Rural
electrification was expensive because of the low density of users. Has a
lot of this been replaced with a wired-neutral/ground?

 

[daestrom]

Thanks, Don, and all who replied. It seems that saving a few bucks on
wire wouldn't offset the disadvantages of using soil in place of
copper/steel. I'm an EE by profession (not that well-versed in power
distribution systems) but SWER seems kind of silly when all the
alternatives are weighed. Sincerely,

Another thought that came to mind about this is the cost of wire versus
the total cost of the line.

Using SWER cuts the wire costs in half, but doesn't change the number of
poles needed. If the second wire is a multi-grounded neutral, there is
no cost of insulators for this wire.

In the Australian outback, I can imagine the cost of poles or towers is
higher than in rural North America where wood poles are easier to come by.

But this would argue against SWER versus traditional two wire since the
savings would be a smaller percentage of the line's total cost.

Thoughts?

daestrom

 

[Guest]

I did a little research as I was not familiar with this term and was
amazed that farmers would even try this, based on my experiences at the
company I used to work at. Using the earth as a neutral, particularly in
Canada or the northern US where the soil conditions can change
dramatically over the course of the year is foolhardy and dangerous.
Protection systems, particularly GFI would not work correctly if at all.
The farm animals, being 4 legged, are more susceptible to step potential
than we are. In a fault condition that step voltage could get quite high.

The research I did came up with a paper written back in 1947 for New
Zealand, and a WEB site titled "RuralPower.org" which advocates it but
seems directed towards countries like India and Nigeria.

--

\\\|///
[ @ @ ]
.........o00o..(_)..o00o.........

Cheers .,. Bob
PEng Retired

It wasn't the farmers who did this-the utility would run a 6900V hot wire
and at each service point the transformer was (and still is) connected from
this to ground. The ground current would follow the line but its spread
would be dependent on soil conditions. I am going from recall in the late
40's, early 50's when rural electrification was new and growing at a great
rate. Your NZ paper indicates 1947 which is in that period- and the
practice was used by North American utilities such as the then Calgary Power
and Canadian Utilities in Alberta and Saskatchewan. If I recall correctly,
the first such rural system in the region was installed about 1947 in
Swalwell, Alberta. (I am assuming that you are familiar with these
names -guessing from your service provider)
However, the practice didn't last long (to the mid 50's or so) before a
return wire was installed (in parallel with the ground path) so potential
problems were recognized.

I hope that I didn't imply that the farmers used the ground as neutral.

 

[Guest]

Another thought that came to mind about this is the cost of wire versus
the total cost of the line.

Using SWER cuts the wire costs in half, but doesn't change the number of
poles needed. If the second wire is a multi-grounded neutral, there is no
cost of insulators for this wire.

In the Australian outback, I can imagine the cost of poles or towers is
higher than in rural North America where wood poles are easier to come by.

But this would argue against SWER versus traditional two wire since the
savings would be a smaller percentage of the line's total cost.

Thoughts?

daestrom

As I recall, the ground wire when used is typically mounted on a small metal
bracket which is cheaper than an insulator. As for questions regarding
the cause of stray voltages- I recall that courts in Wisconsin agreed with
the farmers. The effect of ground currents will depend on the location of
the line with respect to the farmers buildings -noting that AC ground
currents follow the line and the effective spread of current is dependent on
soil conditions. Certainly Tom Horne's comments are not to be ignored
although I am not fully convinced at this time I must admit that other
than studying an analysis about 30 years ago, I haven't been involved with
this problem - nor have I heard of it being a problem in the area where I
lived.

 

[daestrom]

I did a little research as I was not familiar with this term and was amazed
that farmers would even try this, based on my experiences at the company I
used to work at. Using the earth as a neutral, particularly in Canada or
the northern US where the soil conditions can change dramatically over the
course of the year is foolhardy and dangerous. Protection systems,
particularly GFI would not work correctly if at all. The farm animals,
being 4 legged, are more susceptible to step potential than we are. In a
fault condition that step voltage could get quite high.
The research I did came up with a paper written back in 1947 for New
Zealand, and a WEB site titled "RuralPower.org" which advocates it but seems
directed towards countries like India and Nigeria.
--
\\\|///
[ @ @ ]
.........o00o..(_)..o00o.........
Cheers .,. Bob
PEng Retired
Bob
The farmers didn't try it. The utilities did. All the farmers did
was use the power from the utilities that used the Multi Grounded
Neutral (MGN) distribution system that is the standard methodology in
public power distribution in North America. I suppose the
misunderstanding of what I was saying was my fault because I was
contributing to thread drift while replying to Don Kelley's sentence
"Part of the reason may be the semi-bogus stray voltage argument
(often due to poor secondary wiring -but - hey, lets sue the
utility)."
Since I have done rural farm wiring and many who talk about it have
never set foot on a dairy farm I take umbrage at people falling for
the utility industry propaganda that stray voltage problems are caused
by poor secondary wiring rather than by the Multi Grounded Neutral
distribution system that would cost the utilities millions to
replace. MGN distribution is not widely used in Europe because they
learned from our mistakes. Their animal husbandry industries do not
suffer from stay voltage problems even though some of their farm
wiring also dates from the dawn of electrification. The fact is that
the voltages used in secondary wiring on farms in North America are
too low to cause most of the stray voltage problems that are
complained about by dairy farmers. What does cause quite a few of
those problems is the inadequacy of the neutral in MGM utility systems
for maintaining a low impedance return path for the High voltage
currents in the utilities distribution systems back to their point of
origin at the substation transformer. As the neutral return path
impedance rises the flow of current through the earth from utility MGN
grounds back to the substation grounds and thence to the source at the
substation transformer also increases. As the current flows through
the earth increases so does the voltage across the surface of the
earth through which that current is flowing. It is that increasing
step potential that causes the health and behavioral changes in live
stock. The stock power utilities allege that the stray current is
caused by the condition of the secondary wiring of the affected
farms. But if you look at a schematic of a farm's wiring before and
after upgrading to isolated neutrals in the entirety of the farms
secondary wiring you will find that the stock utilities spin does not
stand up to careful scrutiny. In both the before and after case you
have a deliberate ground connection at each building on the farm. In
the before case those connections are on the neutral in the after case
they are on the equipment grounding (actually equipment bonding)
conductors. Both sets of conductors provide a continuous low
impedance pathway back to the utility transformers secondary and the
MGN which is common to both the transformers primary and secondary
windings.
The deliberate, code required connections between the farm's secondary
wiring and the earth are not the cause of the stray high voltage
current that flows over those conductors from the MGN to the superior
grounding electrodes located on the farm during that currents travels
back to the substation transformers that are the source of the high
voltage current in the first place. The utility's MGN grounding
electrodes consist of a flat coil of untinned copper wire on the
buried butt end of the utility pole or, at newer poles, a single
galvanized steel rod driven adjacent to the pole. Notice that driving
an eight foot ground rod immediately adjacent to the buried pole is a
violation of good grounding practice in that it does not provide an
undisturbed shell of soil which is the length of the electrode in all
directions away from the rod. Now contrast the likely impedance to
earth of those utility installed electrodes on the MGN to the code
required grounding electrodes that the electrician or the farmer /
rancher her / him self installed on the farm's secondary wiring. On
an older farms early technology secondary wiring instead of the
aforementioned butt coils and driven rods there will be a metal well
casing that is often hundreds of feet deep, underground metal water
piping dozens of feet long buried below the frost line, and driven
rods at barns and milking parlors that are continuously doped by
animal urine thus improving its connection to the earth. While it is
true that some of those electrodes will be badly corroded the dairy
farmer and her/his stock are better off if those electrodes are poorer
than the utilities. In actual practice that is seldom the case. On a
newer or newly rewired farm the electrodes are likely to be no less
effective. There will be Concrete encased electrodes at each newer
farm building that has a concrete foundation or footing. There will
be a genuine Ufer grounding array in the floor of any recently rebuilt
milking parlor. All of these on farm electrodes are of lower
impedance than the utility installed grounding electrodes. It should
not be any surprise then that the high voltage return current flows
heavily on these distributed private premise grounds that are so
carefully and deliberately attached to the utiltity's MGN by the
service neutral conductor and the main bonding jumper at the service
equipment. (Customer Service Unit for our overseas cousins.) It is
this high voltage current flow that generates step potentials beyond a
dairy cows tolerance as it spreads out into the earth away from the
farms superior electrodes.
Exacerbating that problem is that stock utilities are now managed by
bean counters rather than by electrical engineers. As a result of
Corporate America's obsession with stock price and quarterly earnings
reports the bean counters reduce the staff of skilled unionized labor
that maintains the outside plant as a quick way to cut costs. Thus
neutral connections on the MGN deteriorate and ground return current
rises. There are some utilities, most often consumer owned rural
electrification cooperatives, that have addressed these problems
successfully. Some have installed special transformers that provide a
high impedance on the connection to the customers neutral. Having not
had the opportunity to examine one up close I have no idea how they
accomplish that. Others have resorted to providing isolating
transformers at dairy farms in place of the regular pole pig. Some
have also resorted to using transformers with two high voltage
bushings in place of the cheaper one bushed one bonded type with the
primary connected across two primary lines without an MGM connection
on the primary side of the transformer. That latter practice is only
effective if it becomes wide spread on any given distribution
circuit. What I haven't ween tried that might be both effective and
cheap would be to use small light truck mounted drill rigs to rapidly
install sectional driven rods to the depth it takes to achieve single
digit ground impedances. That technique was often used successfully
in McCullough loop fire alarm systems were the back up signal path for
the forty eight volt 200 mA current was via ground return.
Ok. I'll put my soap box away now.

Tom,
I have often wondered if the impressed current cathodic protection
system used on the trans Alaska pipeline causes moose to stop giving
milk and thereby causing calves to die from starvation.
The impressed current systems use very long anodes run parallel to the
underground portions of the pipeline about 6 feet away. The cathode
side or negative side is connected directly to the metal pipe. The
anodes are a copper wire embedded in a carbon wrap that allows the
current to disperse along the entire run which can be up to several
miles long per rectifier. The voltage is adjusted to current and can
be as high as 30 volts. Moose are common along the pipeline
corridor. Civil engineers design these systems for the pipeline
company..

Apples and oranges. They both grow on trees. They both provide food
for all sorts of creatures. But you wouldn't call them the same thing
now would you. How far does that cathodic protection current have to
travel through the soil. Six feet you say verses say six miles. You
say the voltage is as high as thirty volts as compared to a rural
utility distribution voltage of say 13.9 kV. The current comes from
rectifiers so it's Direct Current correct? And this has something to
do with High voltage return current from the Multi Grounded Neutral of
an AC utility distribution system how?

Actually, as I understand cathodic protection used on mothballed Navy
ships, you don't need very much current at all. The idea is to apply
just enough voltage to counteract the voltage created naturally by the
dissimilar metals in an 'electrolyte'. You could *theoretically* tune
it to exactly counteract this potential so no galvanic current flows and
no corrosion occurs.

I mean, the stuff the Navy used to protect ships in long term storage
was in the mA range. Too high a current and your electrode corrodes
away faster than the hull would rust if you have nothing at all. Then
you just have a bare wire touching the water line and less protection.

I'd imagine the same is true for this set up, you want a small potential
developed to counteract the natural galvanic action, but it doesn't have
to be any sort of massive current.

daestrom

 

[Guest]

When I took myPE exam, it was the first time in a long time when it had
no problem on symmetrical components in a long time. In many ways, that
is now passe. At UCLA now, for example, AFIK, there is not even a
mention of symmetrical components or even three-phase in the EE course.

Undergraduates now get at least one intensive course in linear systems
which includes much of linear algebra and matrices. The symmetrical
components reduces to a subspecialty of eigenvalues and eigenfunctions
using complex functions including the operator corresponding to the cube
root of -1.

Is this a good trend. I do not know. It may be a good mathematical
background with much application. On the other hand, most of the
students are not likely to know how to use a soldering iron. Color
code--what is that. Being a radio amateur these days would seem to be
unrelated to be preparation for electrical engineering. Figuring out
what to dow with a wound rotor induction motor is not going to be a
career enhancer.

I think that your response was directed to another thread -re symmetrical
components rather than single wire earth return.
In the last 40 years, there has been a change in EE curriculum such that
many schools don't deal with the "power" side. There are still schools
that do still include such things as power systems, symmetrical components,
etc in both the US and Canada. Still important but low on the glamour scale.
Do any engineering schools, with or without 3 phase, deal with the use of
soldering irons- did they, even in the '50's? It seems to me that this was
something you picked up.
If you want a bad trend- some even replace circuits labs with "virtual
labs" or computer simulation of a circuit.

Somehow, I never considered symmetrical components in terms of eigenvalues
and eigenfunctions but simply as linear transforms from one set of
coordinates to another set (and not necessarily keeping power invariance as
in direct/quadrature axis models for machines).
Of course much of the utility of symmetrical components is that except for
untransposed lines, mutual coupling between the sequence impedances of an
element are 0 or too small to worry about. It is interesting that
Fortesque's original paper is now summarized in a fraction of the printed
space- it originally took about 1/3 of the year's AIEE transactions- a very
long paper .

 

[daestrom]

I think that your response was directed to another thread -re
symmetrical components rather than single wire earth return.
In the last 40 years, there has been a change in EE curriculum such that
many schools don't deal with the "power" side. There are still
schools that do still include such things as power systems, symmetrical
components, etc in both the US and Canada. Still important but low on
the glamour scale.
Do any engineering schools, with or without 3 phase, deal with the use
of soldering irons- did they, even in the '50's? It seems to me that
this was something you picked up.
If you want a bad trend- some even replace circuits labs with "virtual
labs" or computer simulation of a circuit.

I've noticed that a lot of the 'on-line campuses' are going this route.
Of course not all on-line schools are the same caliber, but 'virtual
labs' provide some amount of 'hands on' even in the on-line schools.

Not the same as burning your finger with a real soldering iron, but
somewhere in between real physical labs and just classroom/book learning.

daestrom

 

[Archimedes' Lever]

WHY DO YOU COMPLICATE YOURSELVES ?

You're an idiot.

OF COURSE WHAT VARIES IS THE BONDING TECHNIQUES BUT SINGLE EARTH
GROUNDING IS COMMON

You are a total retard. That is not what the thread is about, idiot.

YOU MUST HAVE BEEN HUNTING TROLLS WITH THIS TOPIC [;-)]

Is that why your retarded ass showed up?

I SEE YOU WERE SUCCESSFUL TOO

Yes, ProTURDeus, we know that you are a troll.

THE NAMELESS FREAKS FALL INTO THE USER ATTENDED TRAPS FREQUENTLY

You need attending to. At about six feet under.

I AM PROTEUS

You are a goddamned retard.

 

[Archimedes' Lever]

Greetings, all.  Single Wire Earth Return (SWER) AC power distribution
is used in the Australian outback.  Does anyone know if SWER is used
anywhere in the US?  Thanks for your time and comment.  Sincerely,

Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337

WHY DO YOU COMPLICATE YOURSELVES ?

  You're an idiot.

OF COURSE WHAT VARIES IS THE BONDING TECHNIQUES BUT SINGLE EARTH
GROUNDING IS COMMON

  You are a total retard.  That is not what the thread is about, idiot.

YOU MUST HAVE BEEN HUNTING TROLLS WITH THIS TOPIC [;-)]

  Is that why your retarded ass showed up?

I SEE YOU WERE SUCCESSFUL TOO

  Yes, ProTURDeus, we know that you are a troll.

THE NAMELESS FREAKS  FALL INTO THE USER ATTENDED TRAPS FREQUENTLY

  You need attending to.  At about six feet under.

I AM PROTEUS

  You are a goddamned retard.

WHO THE HELL WAS TALKING TO YOU GOSSIP GIRL
GET A LIFE TROLL YOU ARE ADDICTED TO THE DEEP ANAL PROBES I GIVE YOU
OR WHAT ? ? ?
YOU ARE THE ONLY TURD STUCK IN THE PLUMBING HERE FAGGOT
IN TUNE WITH THE NOTION = GO TAKE A LONG WALK OFF A SHORT PIER

I AM PROTEUS

Bwuahahahahahahaha! It actually looks like the drunkard fucktard might
have had a cup of coffee this morning. Still, the utter stupidity shines
through, dumbfuck. You are still stupid, even when you are not drunk.
Please drink more, asshole... die sooner.

 

[JohnHasler]

As recently as 1980s I was working as a Faultman and assisted installing SWER in Marlborough Sounds of New Zealand.

Was used in very remote unpopulated areas where fully overhead systems where uneconomic.

The last one I did we had to mole plough close to 1600m of old copper wire to get the low earth resistance we were required by regulation to achieve.

Done properly very effective and safe.

John

 

[rgvandewalker]

Safety and Cost

I saw some misinformation on this site. The wikipedia has an article on the topic with extensive references.

SWER is safe because the earth circuit is isolated from both users and the generator by transformers, and there's a surge arrestor on the long-line side of each isolation transformer.

I think this is actually safer than a conventional metallic return, because there's less impedance to the safety ground, and less chance for a high voltage lightning event.

A SWER lowers cost in several ways:

1. The circuit's high voltage (19Kv is common) and low current permits use of galvanized steel wire. Steel wire permits 1/3 as many posts as copper, and gives a lot more freedom in routes.

2. There's only one wire.

3. The isolation, earth return and single wire means that it has fewer geomagnetic faults, and no line-clashing. So, it's more reliable than conventional wired-return rural lines.

The biggest problems in a SWER are the line capacitance, and installing good local grounds.

I don't know how the capacitance is usually addressed. I've read a number of methods: Balanced capcitance, Reactive shunts, active shunts,

Grounding is an issue. The standard local ground is 6m of copper driven into the ground. It has to be deep enough to reach a damp area. Dry soil or frozen soil both cause problems.