3 Phase Current Flow

[ggunn]

The fundamental understanding here is that the neutral is a balancing leg, similar to the current carrying conductors in AC. So, one hot leg cannot conduct current by itself without a "pressure relief valve" so to speak. Within each 1/60 of a second, the amount of current in protons flowing to the load will symbiotically produce the same amount of electrons flowing back to the source.

Protons do not flow. Implicit positive charges (holes) flow in semiconductors in the opposite direction from electrons, but a hole is just where an electron could be but isn't.

 

[Julius Right]

The current entering one phase will return through the other two phases. If you don?t have a neutral the sum of all three currents entering the receiver [wye or delta] will be zero.
Let say current per phase[R,Y,B] is IR=I*cos(w.t)+jsin(w.t) ; IY=I*cos(w.t-2.PI/3)+jsin(w.t-2.PI/3) ; IB=I*cos(w.t-4.PI/3)+jsin(w.t-4.PI/3)
If t=0 IR=I; IY=I.[cos(-2.PI/3)+j.sin(-2.PI/3)] ; IB=I.[cos(-4.PI/3)+j.sin(-4.PI/3)]
IR=I,IY=I.(-0.5-j.0.866),IB=I.(-0.5+J.0.866) then IR+IY+IB=0 or IR=-(IY+IB)

 

[mivey]

Protons do not flow.

Not in metallic conductors, but they can (like hydrons) in other materials.

 

[ggunn]

Not in metallic conductors, but they can (like hydrons) in other materials.

Yes, in aqueous acid solutions, protons (hydrogen ions) do indeed flow. I don't think that is what he was talking about, though.

 

[mivey]

Yes, in aqueous acid solutions, protons (hydrogen ions) do indeed flow. I don't think that is what he was talking about, though.

And he wasn't talking about semiconductors either so the broader comparison sticks.

Charge flow with moving positive particles is not just limited to batteries. You can also have it in common things like electrolytic capacitors, mercury switches, fuel cell membranes, gas discharge elements (both natural like sparks and lightning as well as man-made like neon & fluorescent tubes & arc lamps), as well as pure nature like organisms (yes, thine own self), earth, ocean, and sky.

 

[GoldDigger]

Charge flow with moving positive particles is not just limited to batteries.

But only in very limited circumstances (e.g. hydronium) are those particles protons. Other positive ions, yes.

 

[mivey]

But only in very limited circumstances (e.g. hydronium) are those particles protons. Other positive ions, yes.

Correct. And in either circumstance they are more than implicit positive charges but actual moving positive charge carriers.

 

[Sahib]

Charge flow with moving positive particles is not just limited to batteries.

Electrons are light, dynamic and fast moving particles, compared to which heavy positive ions are too slow. I think due to this that battery charging such as for a cell phone takes a long time to complete.

 

[topgone]

Electrons are light, dynamic and fast moving particles, compared to which heavy positive ions are too slow. I think due to this that battery charging such as for a cell phone takes a long time to complete.

You say it takes a lont time to charge your cell phone? That would be like ancient fact with this development!

 

[GoldDigger]

An interesting way of looking at things.

The reason that batteries are slow to charge is that heat is dissipated in the batteries as a result of charging inefficiencies.
To some extent this is because the ions involved in the chemical reactions have limited mobility.
This is one reason that a simple capacitor where only elections are moving on each electrode can support higher charge and discharge rates.
No inefficient chemical reactions are involved.
But I would have thought to attribute it to the lightness of the electrons. It is more their mobility within the metal or semiconductor than their mass that is important.


Tapatalk...

 

[mivey]

Electrons are light, dynamic and fast moving particles, compared to which heavy positive ions are too slow.

Fast or slow, the ions in the battery have to keep up with the electrons in the wire or there is going to be a KCL problem.

FWIW, only the surface electrons on a metallic conductor move near light speed when a electric field is applied. They shift and create net surface charges that lead to the movement of the electrons inside the conductor. This internal movement is relatively slow.

I think due to this that battery charging such as for a cell phone takes a long time to complete.

The light interference at the retinal receptors causes a dynamic slowdown in the charge rate similar to what happens in di-hydrogen monoxide thermal elevation.

 

[mivey]

It is more their mobility within the metal or semiconductor than their mass that is important.

Sounds reasonable. After all, there ain't nothing "slow" about lightning discharges, fluorescent lighting, etc.

 

[Sahib]

Fast or slow, the ions in the battery have to keep up with the electrons in the wire or there is going to be a KCL problem.

Yes, but think this way: the ions initiate the current flow and not the electrons in this case. If the electric conduction is all by electrons, current flow would be faster, higher current, higher rate of charging and so shorter charging period.

FWIW, only the surface electrons on a metallic conductor move near light speed when a electric field is applied. They shift and create net surface charges that lead to the movement of the electrons inside the conductor. This internal movement is relatively slow.

You are forgetting Einstein again: when the speed of a particle with a rest mass approaches the speed of light, its mass tends to infinity. The conductor would simply break off the circuit due to huge weight gain if its surface electrons try to behave that way.

 

[Besoeker]

Electrons are light, dynamic and fast moving particles

Actually, in terms of moving current along a conductor, they move astonishingly slowly.

I did some sample calculations a while back and I know that copying and pasting from a spreadsheet doesn't format well but here goes anyway:

I 1000 A
PI 3.142
r 18 mm
A 1017.87602 mm^2

Q 8.5E+19 per mm^3

e 1.6E-19


v 0.072238082 mm/sec


Worked better than I expected...
This for copper. Note the v. And the units.

I'm sure, since you are an erudite chappie, you will know of the train and tunnel analogy so you will doubtless excuse my indolence in not typing it out here.

 

[Smart $]

Actually, in terms of moving current along a conductor, they move astonishingly slowly.

I did some sample calculations a while back and I know that copying and pasting from a spreadsheet doesn't format well but here goes anyway:

I 1000 A
PI 3.142
r 18 mm
A 1017.87602 mm^2

Q 8.5E+19 per mm^3

e 1.6E-19


v 0.072238082 mm/sec


Worked better than I expected...
This for copper. Note the v. And the units.

I'm sure, since you are an erudite chappie, you will know of the train and tunnel analogy so you will doubtless excuse my indolence in not typing it out here.

In imperial units...

1,000A
2,000kcmil copper conductor
0.00284402in/sec

 

[Sahib]

Bes:
If you apply the same voltage which caused electrons current flow of 1000A in your last post to cause a current of protons, the protons current flow will be lesser due to lower mobility or lower drift velocity of protons. Please repeat your calculation for a current flow of entirely of protons and see for yourself how less the protons drift velocity will be for the same voltage applied.

 

[Smart $]

Bes:
If you apply the same voltage which caused electrons current flow of 1000A in your last post to cause a current of protons, the protons current flow will be lesser due to lower mobility or lower drift velocity of protons. Please repeat your calculation for a current flow of entirely of protons and see for yourself how less the protons drift velocity will be for the same voltage applied.

Didn't check his numbers, but I assume his calculation is based on one electric charge per atom and atom size. The result is the average net flow rate. Additionally we're talking about copper. Proton drift is negligible, right?

 

[Sahib]

Smart $:
When the current is by flow of ions, the current may be lesser than when the current is by electrons for the same voltage. I am trying to make that point.

 

[Besoeker]

Smart $:
When the current is by flow of ions, the current may be lesser than when the current is by electrons for the same voltage. I am trying to make that point.

My calculation is simply for current. No other extraneous factors are involved. Your comment about the voltage is thus irrelevant.

 

[Sahib]

My calculation is simply for current. No other extraneous factors are involved. Your comment about the voltage is thus irrelevant.

Then how would you know heavier ions may have a lower drift velocity than lighter electrons?