Just to record a phasor reference

[rattus]

Phase has been defined as the argument of the sinusoid describing the wave, i.e.,

phi = (wt + phi0), an angle.

I see no problem with using it to describe voltages with different phase constants. The practice is forever burned into our minds.

 

[pfalcon]

The primary coil imparts an EMF that drives the current in the secondary. The voltage in the secondary is created by the current passing through the inductive coils as:
A -----------+-----------> B (240V<0)
We tap at the center to get:
A -----------> N (120<0)
N -----------> B (120<0)
For resolving to the OP question we must use definition (1) which requires that the two legs are measured in a common direction defined by the system.

In the field we reverse our leads using (2) to
B <----------- N (120<180)
to get opposing voltage phases for each leg.
A property that's certainly valuable for the majority of field applications such as full wave rectifiers

But again by definition (1) when we reversed our leads we should have inverted the polarity of the graphic to either:
B -----------> N (120<180)
or
B <----------- N (-120<180) == (120<0)
Again resolving back to the original "in phase" for both legs. No phase angle is being discarded.

This is supported by the basic circuit concepts:
The resistance/inductance of AN == BN since this is how we build a secondary coil (sorry about the obviousness).
The secondary is not actually a supply but an induced coil or load where each leg is E=I*(Rcos+Lsin).
(Rcos+Lsin) does not have direction. The direction of I is imposed by the primary coil and is therefore traveling from A to B or from B to A at any given instant.

 

[pfalcon]

Phase has been defined as the argument of the sinusoid describing the wave, i.e.,

phi = (wt + phi0), an angle.

I see no problem with using it to describe voltages with different phase constants. The practice is forever burned into our minds.

Phase has been defined as the argument of the sinusoid describing the wave, i.e.,

phi = (wt + phi0), an angle.

I see no problem with using it to describe voltages with different phase constants. The practice is forever burned into our minds.

The problem isn't using the world phase for field practice (2). The problem is whether you plan to answer the OP question which requires definition (1). The definitions are incompatible.

 

[iceworm]

[

iwire -
I had understood the 2500+ post, dumptruck load was to be reopened. Is this it? From gar's opening post, I didn't think it was.

ice

As I said in my post when I closed that thread, I planed to reopen in 24 hours unless the other mods had other opinions. Right now it is still up in the air.

For us to put it back would mean one of us would have to edit out the comments. I can tell you that is not an easy task as the jabs and insults are usually interwoven with legitimate comments and no matter how the edits are done everyone will be upset.

The reason I'm asking is I don't particularly care to get anywhere near the dumptruck load. If this is it, I'll get out now.

Personal opinion is gar's op was pleasant and interesting, the following posts were also somewhat interesting. But if this is going to be the continuation of the DTL it would be good to know.

Just a thought, in the interest of preserving gars's thread, and if the other thread is not to be reopened, perhaps the DTLers could start their own again and again and again

Just saying - not telling and certainly not demanding

ice

 

[rattus]

The primary coil imparts an EMF that drives the current in the secondary. The voltage in the secondary is created by the current passing through the inductive coils as:
A -----------+-----------> B (240V<0)
We tap at the center to get:
A -----------> N (120<0)
N -----------> B (120<0)
For resolving to the OP question we must use definition (1) which requires that the two legs are measured in a common direction defined by the system.

In the field we reverse our leads using (2) to
B <----------- N (120<180)
to get opposing voltage phases for each leg.
A property that's certainly valuable for the majority of field applications such as full wave rectifiers

But again by definition (1) when we reversed our leads we should have inverted the polarity of the graphic to either:
B -----------> N (120<180)
or
B <----------- N (-120<180) == (120<0)
Again resolving back to the original "in phase" for both legs. No phase angle is being discarded.

This is supported by the basic circuit concepts:
The resistance/inductance of AN == BN since this is how we build a secondary coil (sorry about the obviousness).
The secondary is not actually a supply but an induced coil or load where each leg is E=I*(Rcos+Lsin).
(Rcos+Lsin) does not have direction. The direction of I is imposed by the primary coil and is therefore traveling from A to B or from B to A at any given instant.

I will just say that Van and Vbn are properly defined as,

Van = 120Vrms@0

Vbn = 120Vrms@PI

The phase constants are 0 and PI,

I can't follow the rest of your argument.

Somehow I get the right answer even by doing it wrong.

BTW, you reversed the graphic TWICE to arrive at an impossible result.

 

[mivey]

...One book reference I found on Google seems to imply that Steinmetz described his concept as a rotating line (probably meaning some form of vector). This means it is really necessary to look at the original 1893 publication.

I have old references that use "vector" and some that use "rotating vectors". As we know, the term phasors was used to distinguish from vectors and the use of "vectors" fell out of favor because of the confusion with space vectors. I would be interested if you find the origin but Steinmetz would be a good guess as, from what I understand, he is the foundational source for most of our AC math and circuit analysis.

 

[rattus]

Just the facts Ma'am!

Just the facts Ma'am!

The simple fact is that if

V1n = 120Vrms @ 0
then,
V2n = 120Vrms @ PI

Nothing can be done with the phasor diagram to change this fact. It is true even without a phasor diagram.

They are inverses. Inverses are PI radians apart! Nuf sed!

 

[rattus]

Swapping Leads:

Swapping Leads:

BTW, swapping leads does NOT change the phase of a waveform. There is no reason to talk about leads when discussing phasors. The phases are what they are and cannot be changed by anything one does with leads or on paper.

Furthermore, the expression Rcos + Lsin make no sense at all. There are no arguments for the sine and cosine? And it is dimensionally inaccurate.

I think the OP's question has been answered satisfactorily. Most people seemed to understand it.

 

[steve66]

The simple fact is that if

V1n = 120Vrms @ 0
then,
V2n = 120Vrms @ PI

Nothing can be done with the phasor diagram to change this fact. It is true even without a phasor diagram.

They are inverses. Inverses are PI radians apart! Nuf sed!

BTW, swapping leads does NOT change the phase of a waveform. There is no reason to talk about leads when discussing phasors. The phases are what they are and cannot be changed by anything one does with leads or on paper.

Furthermore, the expression Rcos + Lsin make no sense at all. There are no arguments for the sine and cosine? And it is dimensionally inaccurate.

I think the OP's question has been answered satisfactorily. Most people seemed to understand it.

You are completely wrong.

 

[gar]

120327-1112 EDT

Various tries on the Internet for the inventor of the word phasor produced no useful results. There are references that would imply the name originates from Steinmetz. As I have stated I do not believe this is true.

My book references seem to imply the time frame of the 1940s.

Dictionary.com puts the origin at 1940-1945, but no other information.

Hehre and Harness copyright 1942 does not mention phasor. The entire discussion uses the word vector, and one chapter is on Complex and Symbolic Notation. Most of their vector diagrams are from a single point, even for a delta circuit.

.

 

[jim dungar]

Hehre and Harness copyright 1942 does not mention phasor. The entire discussion uses the word vector, and one chapter is on Complex and Symbolic Notation. Most of their vector diagrams are from a single point, even for a delta circuit.

Russell Mason's book "The Art and Science of Protective Relaying", copyrighted in 1956 by General Electric Co., uses 'vector diagrams'.

 

[gar]

120327-1404 EDT

I decided to try Google Books for searching and I made the latest time Dec 1945. Ten results occurred that referenced "phasor". Several of these are in our library. The total U of M library has around 9.5 million books, and about 0.6 million in the Engineering Library.

Google books results:

1886 a foreign language journal had the word phasor in one location.
1892 Electrical Journal --- a three-phasor generator.
1922 Electrical Communication (Feb 1923) International Western Electric --- phasor diagram
1934 The Design and Use of Instruments
1943 Polytech of Brooklyn but nothing found there
1944 Communications --- references AIEE
1944 Quarterly of Applied Math
1944 Harvard Graduate School of Engineering --- references AIEE
1945 The Electrical Review
1945 Book - Elementary Electrical Circuit Theory - Frazier --- references Prof. Howard Bennett of The University of Wisconsin

I expect there may be one or more articles in the Journal of The AIEE in the 1940 range. Google books only listed a 1930 bound copy.

Several of the above books or journals are in the U of M Library.

.

 

[pfalcon]

I will just say that Van and Vbn are properly defined as,
Van = 120Vrms@0
Vbn = 120Vrms@PI
The phase constants are 0 and PI,
I can't follow the rest of your argument.
Somehow I get the right answer even by doing it wrong.
BTW, you reversed the graphic TWICE to arrive at an impossible result.

You're not following because you're stuck on definition 2, which is shown in the middle graphic of post #22.
Yes, by the end of the post the graphic has been reversed twice.
No, it's not impossible by definition (1) which is where the second reversal takes place, but yes, it's impossible if you can't get off definition (2).

The simple fact is that if
V1n = 120Vrms @ 0
then,
V2n = 120Vrms @ PI
Nothing can be done with the phasor diagram to change this fact. It is true even without a phasor diagram.
They are inverses. Inverses are PI radians apart! Nuf sed!

Correct by definition (2) only.

BTW, swapping leads does NOT change the phase of a waveform. There is no reason to talk about leads when discussing phasors. The phases are what they are and cannot be changed by anything one does with leads or on paper.
Furthermore, the expression Rcos + Lsin make no sense at all. There are no arguments for the sine and cosine? And it is dimensionally inaccurate.
I think the OP's question has been answered satisfactorily. Most people seemed to understand it.

By def (2) swapping leads does not change the waveform. By def (1) it does. Since (2) doesn't answer the OP question about why it's called single-phase we have to discuss def (1) so leads do have meaning.
As to "no arguments for the sine and cosine" I work a lot with mathematicians who use shorthand. Express the arguments as you like as long as they're identical.

 

[rattus]

You are completely wrong.

Pray tell me how?

 

[steve66]

Pray tell me how?

For one of the voltages, pick the other point as a reference. then they are both in phase.

 

[rattus]

You're not following because you're stuck on definition 2, which is shown in the middle graphic of post #22.
Yes, by the end of the post the graphic has been reversed twice.
No, it's not impossible by definition (1) which is where the second reversal takes place, but yes, it's impossible if you can't get off definition (2).


Correct by definition (2) only.


By def (2) swapping leads does not change the waveform. By def (1) it does. Since (2) doesn't answer the OP question about why it's called single-phase we have to discuss def (1) so leads do have meaning.
As to "no arguments for the sine and cosine" I work a lot with mathematicians who use shorthand. Express the arguments as you like as long as they're identical.

As far as I know, there is no official definition for the term 'phase' as used to describe the lines of a multiphase system. But, it is clear that it means that the voltages on legs A, B, and C carry different phase angles, namely A, B, and C. So there is no difference.

You had better come up with a better explanation for Rcos and Lcos. Perhaps you could explain a bit further and tell us how I*L*cos is used? I*X_L makes sense but I*L is just plain wrong. And, the use of trig terms in this expression is wrong as well, plus we are not talking about any currents or inductances anyway.

I have a split phase system in my home, and I am quite sure the phases on L1 and L2 are separated by PI radians. I am sure Tektronix would tell me the same, but try as I may, I cannot change that phase relationship without climbing the pole and rewiring the transformer. Not sure I could anyway since there are only three bushings.

 

[rattus]

For one of the voltages, pick the other point as a reference. then they are both in phase.

Yes, but the reference is stated to be the neutral, and the voltages are Van and Vbn. So I am completely right.

 

[steve66]

Yes, but the reference is stated to be the neutral, and the voltages are Van and Vbn. So I am completely right.

Who says the reference has to be the neutral??

 

[Besoeker]

Who says the reference has to be the neutral??

Two hots and one neutral makes a case for the neutral being a common sense choice as a reference.

 

[iwire]

As far as I know, there is no official definition for the term 'phase' as used to describe the lines of a multiphase system.

You state phase has no official definition yet all along you have been arguing for absolute answers in all these threads.