3 Phase Current Flow

[Besoeker]

In imperial units...

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

Actually a mixture of units.
The Ampere an SI unit.
There is no Imperial equivalent.

 

[Besoeker]

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

I didn't claim to know.
So again, an irrelevance.

 

[Smart $]

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?

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.

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

Bes' is correct. When we discuss electrical circuit current (movement of electrical charges), a discussion of ion flow is superfluous and irrelevant. Extremely simplified, ion flow represents voltage change, not net circuit current flow. Consider the ion flow when a current passed through an aqueous ion solution that has net zero effect on the solution (i.e. the solution is charged and discharged concurrently, meaning there is another current source)...

 

[ggunn]

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

Protons do not flow in semiconductors, either. Holes do, but they aren't protons, they are electron vacancies. The only case I can think of at the moment where you will encounter naked protons in non-plasma matter is in aqueous acid solutions. Maybe on the surface of a platinum catalyst.

 

[mivey]

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.

Current is charge flow. A particle with a bigger charge could move slower for the same current but as GoldDigger pointed out, it is a mobility issue. I will grant you that a huge mass takes more energy to move.

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.

Forgot again? Did not forget it in the first place. Your refusal to learn is astounding at times. Remember this?:

Suit yourself.

Understanding quantities is key. For example, we all know your relative mass increases with velocity: that is the principle. Without the quantity, you may not realize it is not significant until you get really fast.

How fast? Moving from zero to 95 million mph gives a relative mass increase of about 1%. So now you think the principle is millions of mph faster is relatively a small impact.

But not so fast, pardon the pun. When your velocity makes your relativistic mass 1 million times your rest mass, an increase of 1 foot per hour in velocity increases your relativistic mass 52%.

I already have but that teaches you little. I have a suspicion you learn better when the information comes from within.

It seems you learned nothing about the value of quantities. Near light speed does not mean AT light speed. At 500 million mph (0.7456c) you have only gained 50% of your rest mass.

Here is another chance for you to learn something about quantity vs. principle starting at some near light speeds:
0.100c, 67.1 Mmph, 0.5% increase over rest mass
0.200c, 134.1 Mmph, 2.1% increase over rest mass
0.300c, 201.2 Mmph, 4.8% increase over rest mass
0.400c, 268.2 Mmph, 9.1% increase over rest mass
0.500c, 335.3 Mmph, 15.5% increase over rest mass
0.600c, 402.4 Mmph, 25.0% increase over rest mass
0.700c, 469.4 Mmph, 40.0% increase over rest mass
0.800c, 536.5 Mmph, 66.7% increase over rest mass
0.900c, 603.6 Mmph, 129.4% increase over rest mass
0.950c, 637.1 Mmph, 220.3% increase over rest mass
0.960c, 643.8 Mmph, 257.1% increase over rest mass
0.970c, 650.5 Mmph, 311.3% increase over rest mass
0.980c, 657.2 Mmph, 402.5% increase over rest mass
0.990c, 663.9 Mmph, 608.9% increase over rest mass
0.999c, 669.9 Mmph, 2136.6% increase over rest mass

 

[mivey]

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.

There you go. Since current is charge flow we need only compare the particle charge to get the particle movement for the same current. I seem to recall protons and electrons have the same charge magnitude.

Sahib seems to be confusing particles with charge. The particle is just a charge carrier.

 

[mivey]

Protons do not flow in semiconductors, either. Holes do, but they aren't protons, they are electron vacancies. The only case I can think of at the moment where you will encounter naked protons in non-plasma matter is in aqueous acid solutions. Maybe on the surface of a platinum catalyst.

I would have to search more but "proton conductor" reveals some info.

The point was the difference between intrinsic positive movement (holes) and positive charge carrier movement (particles) and that current is not just restricted to the movement of electron charge carriers.

 

[mivey]

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

How refreshing to hear sound logic. Good to hear from you this morning. Have fun at the dance.

 

[Besoeker]

How refreshing to hear sound logic. Good to hear from you this morning. Have fun at the dance.

Thank you kindly!
I'm sure the dance will be electrifying if not edifying.......

 

[Sahib]

Current is charge flow. A particle with a bigger charge could move slower for the same current but as GoldDigger pointed out, it is a mobility issue.

But don't you agree heavier ions have lower mobility i.e lower drift velocity than lighter electrons for the same voltage?

It seems you learned nothing about the value of quantities. Near light speed does not mean AT light speed. At 500 million mph (0.7456c) you have only gained 50% of your rest mass.

Here is another chance for you to learn something about quantity vs. principle starting at some near light speeds:
0.100c, 67.1 Mmph, 0.5% increase over rest mass
0.200c, 134.1 Mmph, 2.1% increase over rest mass
0.300c, 201.2 Mmph, 4.8% increase over rest mass
0.400c, 268.2 Mmph, 9.1% increase over rest mass
0.500c, 335.3 Mmph, 15.5% increase over rest mass
0.600c, 402.4 Mmph, 25.0% increase over rest mass
0.700c, 469.4 Mmph, 40.0% increase over rest mass
0.800c, 536.5 Mmph, 66.7% increase over rest mass
0.900c, 603.6 Mmph, 129.4% increase over rest mass
0.950c, 637.1 Mmph, 220.3% increase over rest mass
0.960c, 643.8 Mmph, 257.1% increase over rest mass
0.970c, 650.5 Mmph, 311.3% increase over rest mass
0.980c, 657.2 Mmph, 402.5% increase over rest mass
0.990c, 663.9 Mmph, 608.9% increase over rest mass
0.999c, 669.9 Mmph, 2136.6% increase over rest mass

You need be specific about the surface electron initial velocity. Give a value for it. Simply stating that its velocity is near light velocity could mean any value for its rest mass: it could be equal to that of an adult elephant given its velocity is assumed sufficiently near that of light.

 

[Sahib]

I didn't claim to know.
So again, an irrelevance.

Marvelous. You put up one lone statement in post#54 and when I tried to involve you in the discussion about ions vs electrons mobility, you dubbed my attempts as irrelevant.

 

[Sahib]

You need be specific about the surface electron initial velocity. Give a value for it. Simply stating that its velocity is near light velocity could mean any value for its rest mass: it could be equal to that of an adult elephant given its velocity is assumed sufficiently near that of light.

Corrigendum
The word 'rest' be replaced with 'moving'.
Thanks.

 

[Besoeker]

Marvelous.

I appreciate your appreciation.

 

[Sahib]

I appreciate your appreciation.

Again standalone statement!

 

[Besoeker]

Again standalone statement!

I agree.

 

[Smart $]

Actually a mixture of units.
The Ampere an SI unit.
There is no Imperial equivalent.

While you are correct in there is no Imperial equivalent, I consider Ampere as a universal unit. Ampere was never an Imperial unit. It is included in SI units, but SI by name has only existed since 1960, and Ampere existed well before that. Prior to 1960, SI was known as the CGS system (c.1874).

The sizes of the coherent CGS units in the fields of electricity and magnetism, proved to be inconvenient so, in the 1880s, the BAAS and the International Electrical Congress, predecessor of the International Electrotechnical Commission (IEC), approved a mutually coherent set of practical units. Among them were the ohm for electrical resistance, the volt for electromotive force, and the ampere for electric current.

Read more at links below...

http://physics.nist.gov/cuu/Units/history.html
http://physics.nist.gov/cuu/Units/ampere.html

DISCLAIMER: I am aware the write up on the links may be somewhat biased

 

[Besoeker]

While you are correct in there is no Imperial equivalent, I consider Ampere as a universal unit. Ampere was never an Imperial unit. It is included in SI units, but SI by name has only existed since 1960, and Ampere existed well before that.

Indeed it did. As did most electrical units for which there is no Imperial equivalent.

Prior to 1960, SI was known as the CGS system (c.1874).

Then MKS.
I had the pleasure - and pain - of growing up with Imperial, CGS, MKS and SI.
In UK we are mostly SI but some old Imperial measures persist. Our speed limits are in miles per hour and fuel consumption in miles per gallon. Yet fuel is sold in litres.
Go to the pub, order beer for myself and a wine for the missus. The beer is served in a pint glass. The wine is typically 175ml for a medium glass or 250ml for a large glass.
Groceries are, for the most part, dual marked. Mrs B cooks and bakes. Recipies often come from the internet posted on some of the forums she inhabits. So mostly American and Imperial measures. For weights or volumes the conversions are straightforward. The use of volume for weight can be a challenge. Ounces on a measuring jug meaning fluid ounces......

But, for engineering purposes, pretty much everything is SI unless it's very old.

 

[ggunn]

=======================================================================================

3 Phase Current Flow

Greetings Everyone.
Just trying to get some old stuff revised but cant seem to do it.need help.

When we have a single phase load say a bulb, there are two wires connected to that bulb.
1. Hot Wire 2. Neutral Wire.

the current flows from the hot wire and then returns back via neutral wire. this way current completes its path.

when we have a balanced 3Ph system( STAR or WYE), each phase draws the same amount of current and the neutral current provides the return path.

How is the return path provided incase of DELTA system?there are only 3 phases.so how is return path provided if we have a 3ph load for delta system.

Thanks
=======================================================================================================


I just wanted to remind everyone, myself included, what this thread is about.

 

[mivey]

the current flows from the hot wire and then returns back via neutral wire. this way current completes its path.

don't forget it is reversed on the other half cycle.

when we have a balanced 3Ph system( STAR or WYE), each phase draws the same amount of current and the neutral current provides the return path.

No. The neutral only returns the unbalance. The return duty is shared by all three phases at different times. For instance, when one phase of a balanced system has the maximum current out, the other two share the return current (one phase is positive and the other two are negative.

How is the return path provided incase of DELTA system?there are only 3 phases.so how is return path provided if we have a 3ph load for delta system.

The returns don't all happen at the same time for each phase so they rotate the duty in cycling portions. It becomes clearer when you look at the graph of all three together.

 

[ggunn]

don't forget it is reversed on the other half cycle.

No. The neutral only returns the unbalance. The return duty is shared by all three phases at different times. For instance, when one phase of a balanced system has the maximum current out, the other two share the return current (one phase is positive and the other two are negative.

The returns don't all happen at the same time for each phase so they rotate the duty in cycling portions. It becomes clearer when you look at the graph of all three together.

All those quotes you attributed to me were from the OP, not me. I should have replied with quote to the OP rather than cut and paste; my bad.