May I ask a question about the single vs two phase stuff

[mivey]

"Independent from each other" strikes me as a poor choice of words. I think your point is that they differ. But as long as they are derived from the same HV primary phase (or as gar pointed out, the same generator shaft), then they aren't entirely independent.

But pretty much so.

I also disagree with you about the L1 and L2 loads not being in series. It is only on the assumption that the resistance of the N conductor is negligible that you can ignore how they are in series.

Re-think that.

Trace a current path from L1->line#1wire->load#1->neutral#1wire->N

Then a current path from N->neutral#2wire->load#2->line#2wire->L2

Why would you ever think the current for load#1 would ever jump from load#1->load#2?

The neutral conductors and tie to the N terminal makes them not in series and the more the loads differ the more apparent that becomes.

Only by opening the neutral do they become a series circuit. You might could say the same applies for a perfect load match and perfect winding match but that would be an extreme cases.

 

[mivey]

You'd just have two arrows sticking out in opposite directions, and you'd still have people arguing whether the second arrow got there by rotation about the center point or going back through the center to the other side.

Yeah but why not? We have argued about everything else.

 

[mivey]

I'm really not catching your drift here. The two compass needles responding to the local magnetic field will both point the same direction.

The point is the reference is what defines the system.

Synchronizing two carburetors does not make them the same carburetor. They work together and may or may not face the same direction.

 

[jumper]

Yeah but why not? We have argued about everything else.

Because then I gotta let Ben invite ELI the ICE cream guy to the party and I do not want to.

Hard enough get through this using basic sine wave signals and a resistive load.

 

[mivey]

The two compass needles responding to the local magnetic field will both point the same direction.

Think about your compass system with a 120/208 system.

At some time, it will point from L1->N and from N->L2. Using your logic you would then have to say you have 120@180d and 120@120d that sum to give 208@150d. This is perfectly valid but just not the way we normally define the system.

In reality, you are perfectly content to say you have 120@0d subtracted from 120@120d that gives 208@150d.

This does not agree with your compass. Neither does the 120@0d and 120@180d system but it is also perfectly valid.

 

[mivey]

No, the two phases are dependent, in that V_L1-N(t) + V_L2-N(t) = 0. That is the definition of dependent vectors.

Cheers, Wayne

Well they are not dependent then because they will practically never be exactly the same like you are thinking.

The two winding halves can have voltages quite different from each other. Even unloaded they are not exactly the same due to physical construction variance.

 

[mivey]

Does the load not effect the primary voltage in any way?[ /quote]Of course.

How about the spin of a generator shaft?

Yep.

 

[mivey]

Should I take that as an admission that a load on one phase does effect the waveform on the other phases, in some way?

What does this have to do with the previous discussion?

It does.
Who knows?

 

[mivey]

Because then I gotta let Ben invite ELI the ICE cream guy to the party and I do not want to.

Hard enough get through this using basic sine wave signals and a resistive load.

If it were easy then anybody could do it.

 

[__dan]

I have no clue who is arguing what. Truly if there is some point to be made, it escapes me. The word is convolution, not obfuscation.

You can name the system supply whatever you want. If you want to communicate with others, it may help to use a shared naming convention. If there is a shared naming convention, or a disputed one, it is not clearly readable in this thread.

What I want to know is, what are the independent variables.

You have the A phase and the B phase (or L1 and L2 for the misogommists). Forget about the load for the moment. Are A and B independent variables. The useful math describes the physical observable reality.

If B is always -A because of the physical reality of the equipment construction and its limitations, B = -A, the expected methodology is substitute this in to reduce the apparent complexity, to a system of one independent variable, A and -A. You may call this one phase or two or any other name, but the B phase is not an independent variable, because of the physical reality limited by the construction.

The load can be anything. The load is an independent variable because of the physical reality of its construction. With a load on A and a load on B, load B can be anything different from A, you are introducing two more independent variables.

Here I would suggest the naming convention relates to the supply characteristic and not the load (which can be anything).

Adding the load to the supply is a convolution. Certainly you can change the bus voltage by using the characteristic supply impedance with a distorting load, but you are not creating a new supply voltage as an independent variable, only a convolution of the supply with the load (which can be anything).

You have a ways to go to the 1200+ posts each of the two prior threads on this. What is actually being argued.

 

[jumper]

If it were easy then anybody could do it.

A cave man can buy insurance, but we cannot get through a basic tranny setup and simple analysis.....mind boggling.

 

[drktmplr12]

Still looking for dialogue on what would be different with distorted waveform on true 180 vs -1.

In both cases the distorted current waveform would appear on the neutral, I would think. Once it reached the neutral bar it will travel on the ground system in an attempt to return to the source that generated it, however many paths there are.

I don't see why inversion vs phase shifting should change that. If anything phase shifting would trap the distortion and prevent it from reflecting to the primary, similar to 18 pulse phase shifting transformer. what is seen on the secondary would be the same.

Sent from my Pixel 2 using Tapatalk

 

[Ingenieur]

ok gents/ladies

number 2!!!!

 

[jumper]

ok gents/ladies

number 2!!!!

Easy, peasy to outdo 809 posts if we behave.

And I is not no gent no how.

 

[jaggedben]

...

The impedance of the neutral, from the neutral bar to the service is negligible because in most cases the neutral current will be near zero.

??? Typo? Did you mean resistance instead of current. I agree that 'negligible' and 'near zero' are synonymous.

The loads on each leg do not form a series circuit. That would imply the currents must travel back to the service point and then back through the neutral, through l2 loads, then through l2 line conductors to return to the source. Why would they do that when they can return to the source once they hit the neutral bar? Lower impedance path.

First, to the extent that the loads are balanced and cancel out current on the neutral, the current flows in exactly the path you describe. [EDIT: Not exactly the path you describe. Current travels from L1 to L2 without traveling at all on the shared neutral, other than at the node where it connects to the load neutrals.]

Second, the impedance of the neutral conductor is never actually zero. However negligible it is, it's enough to force some tiny amount of current to 'go the other way' and return through the L2 load conductor, and coil, just as you say. If the neutral develops a non negligible resistance then the change in current (and voltage!) on the other leg won't be non-negligible either. That's when it really will start to behave like a series circuit. But conversely, since the neutral impedance never entirely goes away, the series circuit behavior never entirely goes away either.

...

I fear this part of the discussion is a tangent. I believe it came up because buffalo tried to use 'series' to argue about 'phase'. That strikes me as a semantic game that I don't have a personal stake in. However, we should all be able to acknowledge that current can and sometimes will travel from L1 through a load, to the shared neutral node, and then through a load to L2 and back to the source, without traveling on the neutral. Using 'series' to describe that behavior seems reasonable enough to me.

 

[jaggedben]

But pretty much so.

Re-think that.

Trace a current path from L1->line#1wire->load#1->neutral#1wire->N

Then a current path from N->neutral#2wire->load#2->line#2wire->L2

Why would you ever think the current for load#1 would ever jump from load#1->load#2?

The neutral conductors and tie to the N terminal makes them not in series and the more the loads differ the more apparent that becomes.

Only by opening the neutral do they become a series circuit. You might could say the same applies for a perfect load match and perfect winding match but that would be an extreme cases.

See previous post.

I'm sure you understand this stuff so I'm surprised that you're putting it to me the way you are. Consider that you don't need to simplify it for me.

 

[jaggedben]

The point is the reference is what defines the system.

I'll agree on that narrow point. What I liked about K8MHZ's post was that he seemed to come up with a method to measure the relative direction of the electromagnetic field that was objective, not relying on nomenclature. Consider the two points of the compass needles that point towards the Arctic when under the influence of Earth's magnetic field, and use that to define their direction. Now place those compass needles next to the source coils, one each. Do they point the same direction, or not? It would be nice to know if everyone on this thread can agree. Might help us nail down the 'basics' per jumper.

Btw it occurred to me that a CT meter amounts to much the same thing. There's a right way and a wrong way to set it up.

 

[jaggedben]

Because then I gotta let Ben invite ELI the ICE cream guy to the party and I do not want to.

Hard enough get through this using basic sine wave signals and a resistive load.

:lol: I think laughing is the appropriate response to that, even though I'm not sure I'm clued in on the reference. PM me maybe.

Btw, I take back my last post in response to you about the 'basics'. I'm coming around to your point of view on that.

 

[jumper]

:lol: I think laughing is the appropriate response to that, even though I'm not sure I'm clued in on the reference. PM me maybe.

Btw, I take back my last post in response to you about the 'basics'. I'm coming around to your point of view on that.

It was just a reference to vectors, phase angle, restive vs inductive and capacitive loads, phase shift, and more math with complex numbers. Really do not need to go there right now in my opinion.

ELI and ICE are acronyms.

“Remembering the phase difference

The mnemonic "ELI the ICE man" can be helpful in keeping track of the phase between the voltage and current in an AC circuit.

In a circuit with only an inductor and an AC power source, there is a 90o phase difference between the current and voltage - the voltage leads the current by 90o. This is the ELI part...with an inductor (L), the emf (E) is ahead of the current (I).

In a circuit with only a capacitor and an AC power source, there is also a 90o phase difference between the current and voltage - the voltage lags the current in this case. This is the ICE part...with an capacitor (C), the voltage emf (E) is behind the current (I).”

http://physics.bu.edu/~duffy/sc545_notes06/ELI.html

So, yeah I would like to keep this simple. The basics first and then move on. Too many levels of understanding get involved and it creates confusion.

 

[mivey]

See previous post.

I'm sure you understand this stuff so I'm surprised that you're putting it to me the way you are. Consider that you don't need to simplify it for me.

I know you know. It is just the series result would be an extreme exception as long as the tie to N is good. But I would agree it can happen.