I think this white wire is the 'strap':
It's a Whirlpool Duet Sport (from Costco); I don't have any manuals.
Sorry this took so long. I had to switch newsservers because aioe was triplicating posts, and then dropping them because of the errors. Sigh.
I remember something about a ground connection being no more than 1V from true ground. According to that definition, the third wire could be ground.
Then neutral is a grounded current carrying conductor. This wire is neutral too.
"phase" has a meaning. There's still 2 of them. "split-phase" sounds right too.
I think I've heard about that. Are the phases 90 degrees apart?
The fact that there is this different 2 phase system doesn't prevent the usual one from being 2 phase. That's be like saying you don't have 2 colors of holiday lights if they're just red and green.
I think the people who are denying that it (residential 120/240) is
2-phase are considering the (1-phase) connection to the transformer primary. You still have 2 phases inside.You could be using 2 120V transformers (primaries in parallel, secondaries in series with ground between then), a generator with a
2-phase (180 deg apart) output, or even 2 120V (synchronized) generators. You still have 2 phases.
The manual is here:
From the manual, you seem to have it wired correctly for a 3 wire cord. The white wire that is connected to the screw at the frame on the left side of your picture goes to the neutral to give you 120 volt power where it is needed. This is probably the way it comes from the factory as the diagram says "neutral terminal linked to cabinet. The symble that looks like a 3 prong rake with the W over it is a symble for the frame of an electrical device. The W is for a white wire.
That wire would be reconnected to a differant place if 4 wires are used.
If you unplug your dryer there should be way less than one ohm (small ammount due to about 5 feet of wire) to the wire going from the neutral of the plug to the center terminal on the dryer and also to the frame of the dryer.
This single phase/two phase thing is almost as bad as the WD40 threads.
In the normal house at the pole (on the ground or where ever) the secondary is a center tapped single phase feed to the house. There is very little 2 phase in the US. What is on the other side of the transformer going back to the power company does not mater at all. The transformer converts it to a center tapped single phase feed to the house.
You can't go outside and look at it? It is rather obvious.
Nope. If you must assign a phase relationship (though it's technically wrong) it would be 180 degrees. The phases in a three-phase system are 120 degrees apart. Remember, a circle is 360 degrees (what happened to metric?).
Yes, the generators are three-phase, as is the distribution system.
So far, so good.
Nope, you only get one, and that one is split in half, using a center-tapped transformer (center goes to ground/neutral).
You only see one of the three. Your neighbor might be 120degrees from you (on another leg of the three phases) but you can't see that.
Yes. From it, any variation or number of phases can be easily generated (efficiently). It's just a little trig and a transformer.
Words mean things. The proper term for the Edison connection is "split-phase". It *is* a single phase that is split by a center-tapped transformer (center grounded).
+1
One leg is the opposite of the other by the very nature of the transformer.
Precisely. It starts with the two phases in quadrature (90 degrees) and a transformer to generate any desired phase relationship.
Probably. Not sure what your question is, but 2-phase, where the two are 90 degrees apart is interesting in that any phase relationship and any number of phases can be generated with simple transformers and a (very small) bit of trigonometry. It's quite useful but exceedingly rare.
Two phases generated 180 degrees from each other make no sense at all. It's no more efficient (less, actually) than single-phase and much less efficient than three-phase. There are all sorts of other alternatives, as well. Six-phase is somewhat interesting at times but it's not as efficient as three phase. There's a reason the world uses three.
Yes, though it's possible to balance the two, it would be quite expensive to perfectly do so under all conditions. The fourth wire is cheaper.
Sure.
It would have to be a very high resistance neutral to get a spark. Even if there is no neutral, the voltage on the common point (the neutral on the dryer) would be very close to ground. The imbalance is proportional to the ratio of the current in the heater and the timer. You would measure resistance with an ohm meter. ;-)
No, that's wrong. You only have one phase. It is split into two legs. Words mean things.
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No one is claiming anything is out of phase with itself. The simple statement was made that one of the hot legs of a 240V dryer is out of phase with the other by 180 degrees. Look at them on a scope, what do you see? Phase in this context is just the relationship of one waveform to another. Two waveforms can differ in phase from 0 to 360 deg. With a sine wave, when one differs from the other by 180 deg, they can also be said to be the opposite of each other.
Correct. And when you have one sine wave that is the opposite of the other, it's a 180 deg phase difference. Look at it on a scope or graph it. It doesn't matter how exactly the waveform difference is generated.
Yes and in electrical engineering, the most widely used context of "phase" is simply the relationship of one cyclical waveform to another. Hence, the two dryer hot legs are in fact 180 deg out of phase with each other. Look at them on a scope. What do you see?
and
From the electron's perspective, a mathematical perspective, a physics perspective, what exactly is the difference between saying two signals, waveforms, circuit points, etc are 180 deg out of phase or that one is the inversion of the other?
In degenerate cases
He is calling things by their proper name. You're insisting that a 180 def phase difference of two waveforms must be called "opposite" and not a 180 deg phase difference.
Phase difference is the difference, expressed in electrical degrees or time , between two waves having the same frequency and referenced to the same po int in time.[1] Two oscillators that have the same frequency and no phase d ifference are said to be in phase. Two oscillators that have the same frequ ency and different phases have a phase difference, and the oscillators are said to be out of phase with each other. The amount by which such oscillato rs are out of phase with each other can be expressed in degrees from 0 to 360°, or in radians from 0 to 2?. If the phase difference is 180 degrees (? radians), then the two oscillators are said to be in antiphase.
I replied to your original post explaining why you're wrong.
That is where you're going wrong. You don't take two of the three phase wires, you take ONE of them and put it through a center pole step-down transformer. That gives you two hots and a center connection. Between either hot and the center connection you have 120V. Between the two hots you have
240V. The center tap becomes the neutral. If you look at the waveforms of the two hots relative to the neutral, they are 180 deg opposite each other.
Per the above, all that is wrong.
Yes, at least every one I've ever seen.
Again, as others have pointed out, the unbalanced portion of the load current, which might be lights, timer, etc. is flowing in the neutral
If a neutral is required for an appliance, then it should always be assumed that current is flowing in it.
I believe his question is the same one I have, which is why you insist on referring to a 180 deg phase difference between two AC waveforms only as "opposite" and deny that it is also correct that they differ by 180 degrees in phase. 180 deg is just one possible relationship between two waveforms, where one is the opposite of the other. And that is what you have at the dryer connection.
but 2-phase, where the two
Except of course to run the dryer, because regardless of whatever you want to call it, there are two hots going to that dryer that differ in phase by 180 deg. If you were in an EE physics, or math course and they presented you with a voltage vs time graph of two waveforms that you would get from an oscilloscope hooked up to:
Hot 1 to neutral and Hot 2 to neutral
And they asked, what is the phase relationship of these two voltage waveforms, what would your answer be?
Hi, Draw the wiring out to visualize, it is just one winding with center tap!
two-phase and split phase are different. Reference previous link to two-phase
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