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Are you saying the windings are not out of phase but the voltages across the windings are out of phase?
Why is residential wiring known as single phase?
- Thread starter TimWA
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Are you saying the windings are not out of phase but the voltages across the windings are out of phase?
Rick Christopherson
Senior Member
Funny that you should ask......:lol::lol::lol:
What you're displaying is the potential difference between V1 and V2 as the distance between the curves. It's still just a simple voltage divider.
The equivalent in a DC circuit is to connect a load between the two poles of a 24V battery. Then ground the center of the load. Put that on your oscilloscope and the scope will show +12VDC at one end and -12VDC at the other with 0VDC at the ground point. Both the +12V and -12V are very usable voltages. Despite the two measurements, there is still only one source of power moving across those loads.
Philosophically, AC is DC with a non-zero frequency. V1 to V2 is 240VAC from one end to the other at any given peak. A peak at which you're grabbing a snapshot from an oscilloscope, looking uphill and calling it +120V and downhill to call it -120V at that instance. But it's all still just one hill. Therefore V1 to V2 is a single-phase and you're just looking at the two halves from different directions.
So, take your electronics circuits. Supply two sources at 180 degrees separation rather than a center-tapped single source. How do you keep the two legs synchronized? How do you keep the lead/lag identical? When one load draws excessively and pulls down power on one source what happens to the other leg? Unloaded the two circuits appear identical. They show exactly the same waveforms. But under load they react quite differently.
Actually, phase angles can be applied to anything that is cyclic with a fixed interval.
For example, a square wave which contains harmonics. Which harmonic belongs to the phase angle? The answer is the fundamental, a pure sinusoid. The harmonics carry ever decreasing periods.
If you write out the Fourier expansion, each harmonic would have to carry a different phase angle.
I don't know what your PCBs application was VFD maybe, but for your application if you didn't
need the 100 volts and wanted a center common having them antiphase would be a plus
That would elimanate 100 volt hazard from your equipment.
I know you already know this but residential single phase Transformers are not antiphase the
secondarys are connected in additive configuration.
Rattus I was joking about the waves, the scope would flat line from L1 to L2.
Do you dispute that they are in anti-phase?
Rick Christopherson
Senior Member
Yes, I do. Your voltage measurements may be out of phase, but the windings are not. Or more accurately, "Winding", since it is a single winding with a center tap.
But why do we measure 240V between L1 and L2?
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I believe Bes means the center tapped windings produce voltages which are anti-phase.
Reminds me of something called the "anti-coincidence gate."
Rick Christopherson
Senior Member
No. Even that is wrong because it is an absolute statement.
Van and Vbn are in anti-phase.
As demonstrated in the last pic of #404.
And that this:
Produces this:
Not possible unless Van and Vbn are in anti-phase.
Rick Christopherson
Senior Member
Why did you bother wasting a post on the aspect that's not in contention, while ignoring the aspect that is in contention?
Ummm.....
Let's recap the last few posts.
Rattus #430
I believe Bes means the center tapped windings produce voltages which are anti-phase.
Your #431
No. Even that is wrong because it is an absolute statement.
My #432
Van and Vbn are in anti-phase.
Your #433
Why did you bother wasting a post on the aspect that's not in contention....
Yet you contended it in post #431.
So I'll make it again.
Van and Vbn are in anti-phase.
And yes, it is an absolute statement. With pictures to prove it. Here's another:
T
T.M.Haja Sahib
Guest
You are talking about Van and Vbn only.Why can't you say anything about Van and Vnb?Ummm.....
Let's recap the last few posts.
Rattus #430
I believe Bes means the center tapped windings produce voltages which are anti-phase.
Your #431
No. Even that is wrong because it is an absolute statement.
My #432
Van and Vbn are in anti-phase.
Your #433
Why did you bother wasting a post on the aspect that's not in contention....
Yet you contended it in post #431.
So I'll make it again.
Van and Vbn are in anti-phase.
And yes, it is an absolute statement. With pictures to prove it. Here's another:
Rick Christopherson
Senior Member
Throughout this discussion, no one has ever contested that Van is not inversely related to Vbn. But you are so over zealous in your desire to get the whole world to use your analysis methods that, in my opinion, you deliberately deceive your statements to push this boundary into the absolute definition of a system.
I contested your statements that "the windings were out of phase". When you ignored that contestation and continued on in your path, it suggests to me that your deceptions are knowing and deliberate and not just inadvertent. I cannot abide by that.
I refuse to engage in a discussion with someone that is not honest in their words. Unless you can face up to that, then stop addressing me directly in this thread.
I don't dispute your choice in analysis methods. I don't dispute your designation for Van and Vbn. What I do dispute is how you present this information to others.
I contested your statements that "the windings were out of phase". When you ignored that contestation and continued on in your path, it suggests to me that your deceptions are knowing and deliberate and not just inadvertent. I cannot abide by that.
I refuse to engage in a discussion with someone that is not honest in their words. Unless you can face up to that, then stop addressing me directly in this thread.
I don't dispute your choice in analysis methods. I don't dispute your designation for Van and Vbn. What I do dispute is how you present this information to others.
Did you like the pictures I posted for you in #404?
The first was live to neutral. The second neutral to live. Done at your request, sir.
That aside, it makes sense to consider the neutral as the common point of a 120-0-120 system because it is the common point.
T
T.M.Haja Sahib
Guest
Your pictures are wonderful as much as you are.......
I do not know why you can not put a voltage wave shape and its reverse simultaneously in your scope.How you gave connection in your scope in respect of 240/120 single phase supply?
Because each oscilloscope probe has a signal lead and a ground lead. The ground leads are common so if you connected the two of them opposite ways round to a voltage source, you would short out the voltage source and likely cause damage.
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