Does the earth "complete the circuit" to become ground?

[w_tom]

Look at high voltage transmission towers. Where is the
neutral? Each power circuit is composed of three 'hot' wires.
When at a substation, then three hot wires 'excite' wires on
other side of that transformer. There is no direct
connection. To understand how electricity gets from generator
to that transformer, it arrives as voltage between three 'hot'
wire phases.

Each phase is a sine wave. Each phase is 1/3rd of 360
degrees delayed from the next. A transformer can get voltage
when connected between two hot wires from the generator. Yes
it does get a wee more complex. Best to seek pictures of Wye
and Delta connections before the 'wee more complex' details
are discussed.

Generator outputs three sine waves - each delayed by 5.55
milliseconds (for 60 cycle power). All three are hot. There
is no return or neutral from generator to substation.

The word transmit or conductive return means same here.
Using earth as a return to a generator would create
unacceptable losses for same reason as explained in telegraph
/ telephone example. Generator connects to primary side of
transformer completely different from how secondary side of
transformer connects to the house and earth ground.

Furthermore 'ground' is confusing. Which ground? Earth
ground is only one ground in an electrical system.

Apparently your questions may be based upon what you are
looking at. What is it you see? That would better help
others to more accurately describe what currently you see and
are confused about.

 

[w_tom]

High voltage long distance towers that cut over mountains in
a wide path are three phase and are typically 230K v, 500K v,
or 765K v. Lower voltage distribution lines are 69K v and
125K v. Wires into substation would be three phase - three
wires. Commercial customers typically get all power in three
phases. However where customers don't require all three
phases (ie residential neighborhoods), then each phase serves
customer groups in one-third of that neighborhood. Each phase
powers one third of the utility pole transformers in a large
neighborhood.

 

[Tomi Holger Engdahl]

What exactly is it on those "high voltage lines" that you see everywhere.
Not the telephone poles, but the "high tension" power lines that ride very
high up and cut huge swaths through forests. There are often two lines,
IIRC. Is that one power and one return? Or are they both hot, just out of
phase----though you did mention 3 120 degree phase shifted
lines......interesting.

The practices how "high voltage lines" vary somewhat from country to country.
The two wire "high voltage lines" consist generally of phase and neutral
wires. You can think them as power feed and return wires.

There are "high voltage lines" that have three wires.
Those are used to transport three-phase power (three 120 degree phase shifted
lnes) without neutral.

The very high voltage lines that transport lots of electrical
power tend to be three-phase systems because it is better
for energy transport (less losses per transported kW is
a good reason, and they have also other good properties).
Three phase wiring is the norm when voltages are from tens
of kilovolts to several hundred kilovolts.
And three-phase is also used on many countries widely
at lower voltages (three-phase power is common in many
European countries).

Single phase two wire "high voltage" power distribution is
often seen in the USA in the lines that feed the power to
the distribution transformers that feed that 110V / 220V
power to the building. The voltage on those lines is generally
several kilovolts.

 

[exxos]

Something I've never quite had a model for understanding about: Why does
electricity want to flow to the earth-ground? Is it because the generator
producing it somehow is involved with the earth such that touching the
earth
completes the circuit?

If there is no need to complete the circuit when the earth is concerned,
then for what size planet-body or planetoid does this still hold true?

Look at it simply, the power station is a transformer, the primary is the
generator, and the secondary is the long wires going to your home, your home
is also a transformer which its primary is feed from the power plant, the
secondary is your application voltage. a 2 wiere system, BUT, a ground is
needed and each negative end of the generator is tied to a large ground rod
at the power station. If the power station wasn't grounded the 230VAC on the
secondary of the generator could float up thousands of volts above ground,
so you could have 10,000 volts on the negative and then 10,000+ 230V on the
hot side, the ground ensures that the voltage is always and only 230V above
ground. If it wasn't grounded then the secondary of the generator would
probaby melt itself together due to the offest in voltages within.

The ground in your home does the same, I personally thing is very bad when
equipment don't use the ground at all, the result is you have your 230volts
grid voltage, then your equipment is floating probably 1,000 volts above
ground, it will only ever see 230volts, but if the equipment isn't connected
to earth then if you touch a earth line (such as a radiator) and then touch
the casing of a electronical equipment then you will get a shock. I have
this problem all the time when equipment isn't earthed. From one end of the
house I have a video player which isn't earthed, and a some hi-fi in another
room which isn't earthed, one will be floating 100VAC above ground, the
other probably 500volts above ground, if you touch the 2 cases you have
then 400VAC across you and you know it!

The ground is the referance point to which the 230VAC goes on top of, you
will always have 230VAC but in terms of ground levels you can float up as
high as 10,000VAC or probably even more. This is why there are laws that
all metal work must be grounded.

Chris

 

[Thomas G. Marshall]

exxos coughed up:

"Thomas G. Marshall"


Look at it simply, the power station is a transformer, the primary is
the generator, and the secondary is the long wires going to your
home, your home is also a transformer which its primary is feed from
the power plant, the secondary is your application voltage. a 2 wiere
system, BUT, a ground is needed and each negative end of the
generator is tied to a large ground rod at the power station. If the
power station wasn't grounded the 230VAC on the secondary of the
generator could float up thousands of volts above ground, so you
could have 10,000 volts on the negative and then 10,000+ 230V on the
hot side, the ground ensures that the voltage is always and only 230V
above ground. If it wasn't grounded then the secondary of the
generator would probaby melt itself together due to the offest in
voltages within.

The ground in your home does the same, I personally thing is very bad
when equipment don't use the ground at all, the result is you have
your 230volts grid voltage, then your equipment is floating probably
1,000 volts above ground, it will only ever see 230volts, but if the
equipment isn't connected to earth then if you touch a earth line
(such as a radiator) and then touch the casing of a electronical
equipment then you will get a shock. I have this problem all the time
when equipment isn't earthed. From one end of the house I have a
video player which isn't earthed, and a some hi-fi in another room
which isn't earthed, one will be floating 100VAC above ground, the
other probably 500volts above ground, if you touch the 2 cases you
have then 400VAC across you and you know it!

The ground is the referance point to which the 230VAC goes on top of,
you will always have 230VAC but in terms of ground levels you can
float up as high as 10,000VAC or probably even more. This is why
there are laws that all metal work must be grounded.

Chris

Yes, thanks. The notion of floating voltages is not one unknown to me.
Without a point in space, it can get goofy as to the precise potential of
/anything/. AIUI, voltages have true meaning when compared to something
else. I learned much of this by studying how certain parallel (non-pc)
ports were designed to have every signal line accompanied by either it's own
reference ground, or by that same signal 180° out of phase. No other point
in space needed for those.

A side note, if you can confirm this. A former roommate of mine told me of
a battleship he was given a tour of. Deep in the bowels of the thing he
came across a section where there were huge generators essentially bolted to
the inside of the hull. Their purpose was to de-gauss the ship, which
builds up charge just by being a chunk of metal moving continually
throughout salt water.

Also, I know that a helicopter coming in contact with a ship sometimes has
to worry about potential differences.

Can you confirm any of that?

 

[Thomas G. Marshall]

Thomas G. Marshall coughed up:


....[self-snip]...

I learned much of this by studying how
certain parallel (non-pc) ports were designed to have every signal
line accompanied by either it's own reference ground, or by that same
signal 180° out of phase.

Come to think of it, we called it that, but it's more a figure of speech at
that point, since it's not a fixed-frequency a/c signal. The 2nd line would
probably be the /inverse/ of the first (?). I forget now----s'been 18
years...

No other point in space needed for those.

....[rip]...

 

[exxos]

exxos coughed up:


Yes, thanks. The notion of floating voltages is not one unknown to me.
Without a point in space, it can get goofy as to the precise potential of
/anything/. AIUI, voltages have true meaning when compared to something
else. I learned much of this by studying how certain parallel (non-pc)
ports were designed to have every signal line accompanied by either it's
own
reference ground, or by that same signal 180° out of phase. No other
point
in space needed for those.

A side note, if you can confirm this. A former roommate of mine told me
of
a battleship he was given a tour of. Deep in the bowels of the thing he
came across a section where there were huge generators essentially bolted
to
the inside of the hull. Their purpose was to de-gauss the ship, which
builds up charge just by being a chunk of metal moving continually
throughout salt water.

Also, I know that a helicopter coming in contact with a ship sometimes has
to worry about potential differences.

Can you confirm any of that?

I had this convo of alike a little while ago, backups up by someone who
worked on helicopters, the air ambulance was the one which caught my eye,
since the the thing is in the air is has a floating potential which could be
anything upto about 500,000 volts, and when the doctor drops down on the
metal rope, when his feet touch "ground" his feet have the voltage from the
helicopter travel to ground via him! so he gets a nice shock. The other
example is when the army lift those large metal containers, the guy ontop
who is hooking them up gets a nice shock also and the potential of the
helicopter is grounded. there was a very nice documentry of this a few years
ago on TV.

Bascially anything which isn't hardwired to the "earth ground" (meaning
earth itself) will build up a voltage. Of course it will want to flow to
ground as its a static charge. Even a sky diver will probably be few
thoustand volts above ground, though he will never get zapped since the
closer he gets to ground the less the charge will be.

There has been many tests about this, Bill B might have some stuff on this
on his site about it. Bascially the earth acts like a capacitor, the earth
itself is the negative plate and the ionasphere is the other plate. A nice
idea that your living in the middle of a huge capacitor ;-) I'm guessing
though I think Tesla worked out there was something like 500,000 volts
between plates, I think capacitance was about 30PF ? I'm guessing there,
but the fact remains.

Best to keep both feet on ground and not move or touch anything just to be
on the safe side, well apart from if you get stuck by lightning, that would
be a bummer ;-)

Chris

 

[exxos]

Thomas G. Marshall coughed up:


...[self-snip]...

I learned much of this by studying how
certain parallel (non-pc) ports were designed to have every signal
line accompanied by either it's own reference ground, or by that same
signal 180° out of phase.

Come to think of it, we called it that, but it's more a figure of speech
at
that point, since it's not a fixed-frequency a/c signal. The 2nd line
would
probably be the /inverse/ of the first (?). I forget now----s'been 18
years...

I'm not going to get into phases and such too much, though if you have a
center taped transformer, ground is the center, so you dont have the voltage
float problem, one side will be 180deg possitive in relation to ground, the
other side will be 180deg negative in relation to ground, thats 2 voltages
you have, ground is ground on one side and ground is possitive on the
negative side. You also get a voltage across the neg and pos also, though
you get double voltage, since one is below ground and one above ground, now
if you have 2 loads in series accross that rail, then the centre point
between loads will in fact be 0 volts (if you balanced the loads equally) it
will basically be at ground level but with nothing to tie it to ground its
floating.

A neon sign transformer is a good example, center taped ground on the
secondary, so you get +5KV GND -5KV. if you leave the ground connection off
the the whole secondary will float up a few thousand volts, since the
nearest ground is the 230V primary it will arc over and thus kill it. Some
just tie the negative end of the secondary to ground and tie that to the
negative of the primary also, but then you have 10KV between the secondary
and primary, greater strain on the insulation then using a center tapped
one.

Getting off topic a bit though now, If you checkout split supply rails then
that will explain it all better.
Chris

No other point in space needed for those.

...[rip]...

 

[Thomas G. Marshall]

Well, <blink> *thank you* </blink> to all who replied! I appreciate the
patience, explanations, etc.

My next questions concerning the lowest level regarding quark interactions
to possibly actually "induce" the need for circuits to be complete will
probably be pointed to one of the physics newsgroups.

In any case, you've all added quite a bit to my understanding, filled an
olympic sized hole in my understanding, and that is very /very/ much
appreciated.

 

[R. Steve Walz]

Ok!!! (phew.) Now we've nailed down something I can further munch on.
Someone's gonna post an angry retort soon however, I can just *feel* it....



RIGHT. Good. Now I'm not feeling as *much* an idiot....


What exactly is it on those "high voltage lines" that you see everywhere.
Not the telephone poles, but the "high tension" power lines that ride very
high up and cut huge swaths through forests. There are often two lines,
IIRC. Is that one power and one return? Or are they both hot, just out of
phase----though you did mention 3 120 degree phase shifted
lines......interesting.

----------------------------
Yup, most of the large high-tension towers are three phase, that is
the most efficient transmission modality. There are three conductors.
They are usually arranged in an equalateral triangle for inductive
and geometric voltage symmetry.

-Steve