Complex Power Question, when to use current conjugate

[charlie b]

See the figure. kirchoffs law matter. currents in pu.

I don't understand your point. That figure confirms my statement that the line current in the delta exceeds the phase current by a factor of the square root of 3. In your figure, the magnitude of each line current is 1.0, and the magnitude of each phase current is 0.58. You will note that 1.0 is equal to 1.73 times 0.58 (within a decimal place or two).

 

[Mayimbe]

I did notice that 1/1.73=0.58. From your statement i understood this

I(delta)=I(line)*1.73

english manage issue (for me). sorry

but since we both have agree whats happening to the current in a delta. I think that the nomenclature of it becomes irrelevant. I mean, I can call those current anyway I want, but only if I know whats the difference between them and when to use any of them. A convection matter should i say.

Just my opinion. Not an axiom

 

[bob]

I did notice that 1/1.73=0.58. From your statement i understood this

I(delta)=I(line)*1.73
english manage issue (for me). sorry
Just my opinion. Not an axiom

I line = Idelta x 1.73

 

[Besoeker]

No, it would have current flowing from the source on a "line" and returning on the neutral.
So, given that you agree that the current is flowing between line and neutral, how do you define it?

 

[charlie b]

No, it would have current flowing from the source on a "line" and returning on the neutral.

So, given that you agree that the current is flowing between line and neutral, how do you define it?

It is not flowing BETWEEN line and neutral. Current flows in the "line" (i.e., "phase" or "ungrounded" conductor). Current flows in the neutral (i.e., "grounded" conductor). In some cases, the same current that was flowing in the line, after having passed through the load, will flow in the neutral. In other cases (namely three phase loads), some of the current will return via the neutral, and some will return via each of the other two phases.

You measure current at one point at a time, and when you make that measurement you do not know, and you cannot discern (from any measurement at that location), where the current will flow next. If I put a clamp-on ammeter on a conductor, and get a reading of 10 amps, I am done. There is a 10 amp current flowing at that point. I don't know (and the ammeter can't tell me) if this is a single phase load or a three phase load. I don't know (and the ammeter can't tell me) if the conductor I measured is a phase conductor or a neutral conductor. I have 10 amps flowing past that point at that moment, and that is all I can learn from the ammeter.

 

[Besoeker]

You measure current at one point at a time, and when you make that measurement you do not know, and you cannot discern (from any measurement at that location), where the current will flow next.

If it's a single phase load as I indicated in post #16, you can be pretty sure that the current will flow in the two conductors feeding that load.
If the load is supplied from line to neutral voltage, very common for domestic residences in many parts of the world, the same current will flow in the line and neutral conductors.
You may not wish to see that as line to neutral for both voltage and current. But I imagine many would have no difficulty in understanding what was intended.

 

[charlie b]

If it's a single phase load as I indicated in post #16, you can be pretty sure that the current will flow in the two conductors feeding that load.

Obviously true.

If the load is supplied from line to neutral voltage, very common for domestic residences in many parts of the world, the same current will flow in the line and neutral conductors.

Again, obviously true.

You may not wish to see that as line to neutral for both voltage and current.

Indeed, I do not wish to see it that way, and I am confused as to why anyone would want to see it that way. Current is not measured in the sense of ?from one place to another place.? It is measured at a single place, and the measurement does not take into account where it might go next.

But I imagine many would have no difficulty in understanding what was intended.

And I imagine that many will. Prevention of confusion is my mission here.

By the way, are you really in the UK? If so, perhaps we can arm wrestle over this issue when I visit next week. :grin:

 

[Besoeker]

Prevention of confusion is my mission here.

I don't think anyone would be confused. But we'll let it go at that.

By the way, are you really in the UK? If so, perhaps we can arm wrestle over this issue when I visit next week. :grin

Yes, I really am in UK. As it happens, we have a visitor (a very dear friend) from US staying with us this week and next so I am "officially" on holiday.
Opportunities exist.

 

[mivey]

Current is not measured in the sense of ?from one place to another place.?

Well, kinda-sorta, as we do use "from-to" notation to indicate the current direction, like using "Iab" to indicate current flow in the direction from "a" to "b".

Prevention of confusion is my mission here.

To clarify your point, can you give an example of how this might lead to confusion?

I don't think anyone would be confused.

I agree, just as they don't get confused by the following notation for currents with line-to-ground and line-to-line faults:
IL-G_max
IL-G_min
IL-L

Nor do they get confused by charlie b's use of KWH, which is not correct either. Seems odd to be such a stickler in one case of incorrect usage but to ignore another. I guess we all have our pet peeves.