Four-wire delta, phasors, and Kirchoff:

[rattus]

Set KVL, phase shift, negative magnitude, time delay for a few minutes. Request to mivey, rattus, winnie and any others that like "poor":

Is "yuke" a reasonable extension of "poor"?

If you said, "yes", then is "puke a reasonable extension of "yuke"?

carl

Carl, it is not a matter of what one likes, it is a matter of TRVTH. That is to say, this representation is absolute correct, but it not the only valid representation.

 

[Rick Christopherson]

Looks valid to me. Now draw in the phasor arrows, and you will see that you have reversed the arrow between C & G making that a voltage rise, that is,

+120 + j0.

I nearly fell out of my chair laughing when I read this. :grin: Of course the arrow is pointing the other way. That is the point that we have been trying to tell you all along! As both Jim and I have pointed out (actually this should be properly credited to Jim), this is the reason why you will have a current which opposes your voltage source, because you have drawn your phasor backward. And as I have repeatedly pointed out, this is the reason why it fails Kirchoff.

The counterclockwise voltage from C to G is given by Vg - Vc! You are so hung up on the need to call these two voltage sources out of phase that you are overlooking standard circuit analysis, and they are not out of phase, only your point of reference (with your voltmeter) makes them appear out of phase. The two sources are in series; the current flowing through one is equal to the current flowing through the other. The phasor voltage is increasing from C to G and from G to A. Both phasors point in the same direction.

You have agreed that the nodal diagram is correct, and I believe you are agreeing with the proper way to create a phasor from these voltages, but there is some sort of disconnect that is preventing you from understanding that this all means that your original phasor diagram is incorrect. I have laid this out so carefully that you can't screw it up, yet you still want to change the polarity of the voltage source. WHY do you need to change this polarity? What is driving you to need to draw this backward from its actual phasor representation? (Please do not answer this with a mocking Roman "TRVTH". That is dismissive and insulting.)

This is not a matter of interpretation or of reference. It was a matter of interpretation when you were discussing the "single phase" Vs "two phase" argument, but as soon as you drew the phasor diagram, you took it out of the subjective realm and put is into the absolute realm.

By the way, I have absolutely no idea of what you are referring to as a rise and a drop. I know what these terms mean in standard engineering circuit analysis, but you are using them in such a non-standard way that your meaning completely eludes me.

 

[coulter]

Carl, it is not a matter of what one likes, it is a matter of TRVTH. That is to say, this representation is absolute correct, but it not the only valid representation.

That's a cute answer, but I'm not too good at translating greek or latin, or ratuseze. Please, be clear for us.

Are you contending that the puke "representation is absolute correct" (your words) for a 240D?

Please try and not be ambugious.

winnie, mivey - You want to weigh in on this question?

carl

 

[rattus]

That's a cute answer, but I'm not too good at translating greek or latin, or ratuseze. Please, be clear for us.

Are you contending that the puke "representation is absolute correct" (your words) for a 240D?

Please try and not be ambugious.

winnie, mivey - You want to weigh in on this question?

carl

I mean it is absolutely correct, The summation of phasors around the loop is equal to zero. It is however no more correct than is your preferred diagram.

 

[rattus]

By the way, I have absolutely no idea of what you are referring to as a rise and a drop. I know what these terms mean in standard engineering circuit analysis, but you are using them in such a non-standard way that your meaning completely eludes me.

Rick,

All you have done is redefine one of the phasors and that is valid, but it does not prove me wrong, and if you don't understand voltage rise and voltage drop, how can you criticize me?

And, how is it that my summation equals zero, just like Kirchoff says it must?

 

[rattus]

Please open the attached document for an example of phasor summation around a delta loop.

Since no one else will respond, I will just do it myself.

Solution:

Consider the phasor diagram in partialy.jpg. This is a partial phasor diagram of a 120/208 wye, and the voltages Van and Vbn are represented as two tail to tail phasors.

We will use KVL to find Vab and we will perform the summation around a CCW path. Then,

Vbn + Vab - Van = 0

Vab = Van - Vbn

Vab = 120 + j0 – ( - 60 – j104)

= 180 + j104 = 208 @ 30

Now, the path traversed a phasor head to tail. Does that make my procedure wrong? No, we knew the value of Vab already, and this is one method to obtain that result.

My point is that this little exercise demonstrates that it is correct to use voltage rises and drops when summing phasors. Remember, KVL is defined as an algebraic summation.

Now, can anyone refute this argument?

 

[Rick Christopherson]

Rick,

All you have done is redefine one of the phasors and that is valid, but it does not prove me wrong,

That's ALL I did? Rattus, you can't change polarity just because it suits you. The direction of a phasor is not some random thing that you can flip around on a whim--it has a meaning.

Try this little experiment: Go down to the living room and take out one of the two batteries from your TV's remote control. Turn it around and put it in backward. Now go watch TV.

and if you don't understand voltage rise and voltage drop, how can you criticize me?

I didn't say I didn't understand them....just that I don't understand your use of them.

And, how is it that my summation equals zero, just like Kirchoff says it must?

Because it wasn't a summation. You subtracted. You have the wrong polarity.

Since no one else will respond, I will just do it myself.

Since no one has taken the Bait for your typical distraction to avoid a difficult problem, you are just going to go ahead and argue it by yourself? Address this current issue first and then we can look at what ever you want.

 

[rattus]

I didn't say I didn't understand them....just that I don't understand your use of them.

Because it wasn't a summation. You subtracted. You have the wrong polarity.
Since no one has taken the Bait for your typical distraction to avoid a difficult problem, you are just going to go ahead and argue it by yourself? Address this current issue first and then we can look at what ever you want.

1. If you don't understnad my use of rises and drops, you cannot understand my argument.

2 Let's see some proof that a summation cannot include subtraction.

3. How is it that my summation equals zero like it should?

4. What would happen if we performed the summation in a CW direction?

5. I am addressing this issue. If you refuse to respond, then you forfeit the game because that post disproves your notion about subtraction.

 

[mivey]

Convention vs concept

Convention vs concept

I haven't caught up on this thread yet but just noticed this last post.

2 Let's see some proof that a summation cannot include subtraction.

How is he ever going to "prove" it? If you define summation to include subtraction, then it does. If you define it as not including subtraction, then it doesn't. Pick one definition or the other then re-state whatever it is you said based on that definition.

If one person refuses to use someone else's definition, they are debating convention, not concept. Convention could be something to debate but may not worth it.

 

[coulter]

... If you refuse to respond, then you forfeit the game ...

Oh - oh. I didn't know we were keeping score. I wasn't - guess I lost.

carl

 

[mivey]

Nuff said

Nuff said

I find this dismissive and insulting. If this forum is going to hold me to a standard of decorum, then it should be holding you to the same standard, and so far that does not appear to be equivalent.
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You have been mis-treated. We are all very sorry. :grin:

If I missed it, I really am sorry. I am having trouble keeping up with all the post.

To everyone who violated the decorum: shame on you. I'm calling myself caught up.

 

[Rick Christopherson]

1. If you don't understnad my use of rises and drops, you cannot understand my argument.

I do understand your argument. You want to call these two voltage sources out of phase because that is how you (we--including myself) view them when we look at a load center, or such. This is fine, because from that particular perspective, they appear to be out of phase. This is the flexibility of being able to view circuits from a particular perspective.

However, once you draw a phasor diagram or a circuit schematic, you lose this flexibility of calling them out of phase, or even of opposite polarity--unless you also add a negative sign to the voltage?s magnitude. From a phasor diagram or circuit schematic perspective, the two voltage sources are not out of phase, and they have the same polarity.

From what I have been able to gather over the past several days, you are trying to take this perspective of the two sources being out of phase, and trying to make it an absolute in the diagram, and this is something that you cannot do (again, without adding the minus sign).
==============================================

I thought of an analogy this morning on my drive to a project site. Let?s go back to the TV remote (aka clicker). It has 2 AA batteries connected in series with the negative terminals down and the positive terminals up, as shown to the left. The two 1.5 voltages add together to give us 3 volts total.

When we change our reference point to be at the point between those two batteries, and we use a volt meter to measure the voltages from our reference point, our volt meter will record the upper battery as having +1.5 volts, and the lower battery as having ?1.5 volts. This is shown by the Red text. So we would (could) call them out of phase (or reversed polarity).

Our point of reference has changed, but the batteries have not. This would be like crossing out the labels on the batteries an putting our own markings on it (as shown in Red Text).

You, on the other hand, are trying to redefine the battery itself and say that it is turned upside down, with its positive terminal down and the negative terminal up, and the voltage still being the positive voltage printed on the label (as shown to the right). When you add these two batteries up (i.e. connect them together) you get a total of zero volts across them.

2 Let's see some proof that a summation cannot include subtraction.

I don?t mean for this to sound derogatory, but there is no other way I can say this. I don?t have text books going back far enough to cover such an elemental topic. This is mathematics taught in Elementary School. Summation is addition. Summing a positive number and a negative number is still summation. Subtracting two positive numbers is not summation of a negative, but by definition, is subtraction.

OK, I just thought of a perfect example of why these are different: Add 2 and 3 and you get 5. Now subtract 2 and 3, and what do you get?--well, since I didn?t tell you which number to subtract from the other number, you could end up with either +1 or ?1. However, if I tell you to add 2 and a (-3), then it makes no difference which number you put first, the answer will always be ?1. That is the difference between summation and subtraction, and that is the reason why Kirchoff?s Law specifically states directed summation.

By the way, this is also why vector analysis is cummutative, as I mentioned in my previous posting. This is also why when I rearranged your original diagram, I got a different answer. It is analogous to subtracting 2 and 3 without specifying which one to start with. That's why we don't do this is electrical circuit analysis.

3. How is it that my summation equals zero like it should?

Because you added the minus sign, but called it subtraction. If you had added the minus sign to the phasor/vector, then we wouldn?t be having this argument, and you would also see that the direction is the same as what I have been trying to tell you. p.s. I know that I have now answered this question more than once. Don?t keep asking the same question expecting the answer to change.

4. What would happen if we performed the summation in a CW direction?

Then all of the phasors would be pointing in the opposite direction, and the answer would still be the same. This is why I told you that Kirchoff doesn?t care if it is CCW or CW, so long as you don?t do both.

5. I am addressing this issue. If you refuse to respond, then you forfeit the game because that post disproves your notion about subtraction.

I know your tactics already. You want to distract the discussion away from a difficult problem in the hopes that it will be forgotten and everyone moves on. I fully intend to extend this discussion into the 3-phase wye system, and I actually look forward to that. However, we cannot go down that road until we fix this one first, or we will still have the same problems then.

 

[Rick Christopherson]

You have been mis-treated. We are all very sorry. :grin:

If I missed it, I really am sorry. I am having trouble keeping up with all the post.

This is more of a message to the moderators than it is to you and Rattus, but if I am going to be held to a standard of decorum, then everybody must be held to the same standard. If you and Rattus can lob out disrespectful or derogatory comments and not get reprimanded, then it is inappropriate that the moderators comment on my words.

Case in point: Rattus called into question my credentials, for which, I have publicly answered and stated. However, when I called Rattus' credentials into question and doubted whether he was a degreed engineer, the chief moderator of the forum jumped on this as being inappropriate, and Rattus was relieved of answering my query. As much as I would like to know this answer, I am not permitted to ask the question.

All I was saying, was that if it is permissible for you and Rattus to be throwing out these barbs without repercussions, then I should not be admonished for doing the same. What applies to one, should apply to all.

 

[iwire]

All I was saying, was that if it is permissible for you and Rattus to be throwing out these barbs without repercussions, then I should not be admonished for doing the same. What applies to one, should apply to all.

Drops head in disbelief. :roll: