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File: mwbc.jpg (41 KB, 800x570)
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What is physically happening here? this is a multiwire branch circuit with phases 180 degrees out of phase. As i've heard it explained, the "currents cancel" when they both travel on the neutral and it only carries the net difference. But what exactly is canceling? As I understand it current isn't actually (just) the movement of electrons, so it's not like equal electrons are moving both ways. Is it like the picture suggests and you have two different waves traveling independently and it just "looks" like they cancel on the neutral? do the waves "crash" and completely stop each other from continuing flow? is it just stationary EM fields that cancel where they meet? how are you able to derive power from these currents just "cancelling".
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>>16575129
write the currents as vectors
they cancel
/thread
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>>16575129
magic
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Did the smarter EU browsers get off work yet?
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>>16575129
No, I can't tell you WHAT physically happens in the wire. But I can measure it. I can show it as the summation of two independent out of phase currents. I have a very good understanding of it and that's good enough for me. I'm not distracted by the philosophical side of WHAT happens inside the neutral wire.
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>>16575129
The electricity is just electrons wiggling back and forth. In the middle wire they don't move.
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>>16575129
Who the fuck made this retarded image? Having the bulbs like that is just going to confuse people.
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>>16575158
this
also fun fact if you have capacitor on one phase and inductor on other, current on neutral wire will be sum of phase currents.
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>>16575991
i'm not even asking philosophically. I just want the scientific explanation of what happens. If the load is balanced, you can completely cut the neutral and it changes none of the currents
in each bult. Is that just a happenstance not a general rule? With your summation, the implication is that the phase currents are ALWAYS traveling on the neutral they just cancel out. What would be the difference between that model and one where the current only flows between the top and bottom and only the imbalance on the neutral.
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>>16576229
Is there specific value/ratio inductor/capacitors I would need to use if I wanted to test this out? Does it matter if I use batteries? How does the phase current explanation work when the power is DC?
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>>16576432
in case of pseudo two phase the smaler power factor the better (you want curents +-90 deg out of phase with voltage), in case of 3 phase you want +60 deg and -60deg and you can get difference or sum of currents depending on which two phases you connect (phases are 120 deg apart). With dc Inductors start producing constant magnetic field and then become invisible to DC, capacitors start invisible and then behave as open circuit for DC. If you have +dc, 0, -dc you can only get difference between currents without more fancy electronics components. L to C ratios are for resonance to get maximum power and depends on frequency.
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>>16576564
oh, nvm I think I understand what you're saying. but this is just causing each current phase to lag voltage such that when they meet at the neutral point they're in phase right?

The question i'm trying to answer is whether both phase currents really return on the neutral. If the load is equal on top and bottom, then the two have the same magnitude with opposite signs. So what's the difference between describing it as one current vector along the top and bottom, and two current vectors that cancel along the neutral? where would these two descriptions give different results?
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>>16575129
>phases 180 degrees out of phase
Isn't it just the sinusoids canceling?
It's destructive interferance
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They are 240 volt in ohase and the current flows through one to another. The middle 'neutral' does not carry current.

You get the 120 volt by splitting the 240 with transformer having two coils at output end totaling same amount of voltage. In this you just forget the splitting and use the 240.
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>>16576705
In pseudo two phase current under such circumstances current just goes through whole length of your transformer winding, hot wires, orange part from one bulb to the other and those bulbs and nothing returns via neutral, if everything is perfectly balanced, otherwise some current goes back via neutral and closes loop on half of your winding.
>>16575129
>is it just stationary EM fields that cancel where they meet?
If you look at electric field nothing special happens at orange point. Current just goes from top to bottom and rest of orange wire (from point back to the left) has 0 V/m electric field, 0 V to the ground, 0 A of current
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>>16576726
>>16576876
i get that interpretation. I'm asking how you prove one or the other. If I responded "nope both phases travel along the neutral and cancel so you get 0 V or current", what would you use to show that's not true. In the case of a balanced load, they give the exact same answers for current along each resistor and the neutral. in the case of an imbalance, current on the neutral makes sense because the two waves don't completely cancel, they are mirrored but one has a bigger amplitude. in the view of current flowing top to bottom, you have an imbalance cause....why? if it was working in series before, why would it ever pull any more amps than equal? and why would the current split two ways?
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Lmao at how the EEfags here can't answer your question and keep repeating the same shit over and over again. They don't know what physically happens inside this circuit. They are abstracted away from it by their shitty circuit diagramms and rules applied to them.
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>>16576935
to be fair, I phrased it wrong. I don't actually care what the electrons are "really" doing. I'm asking for the differences if you model it one way vs the other, or if there even are any.
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>>16575129
The middle voltage is always 0v.
If the lightbulbs are the same, this will cut the voltage in half. The halfway point between the 2 endpoints is 0
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>>16575129

https://nationshomeinspections.com/multiwire-branch-circuit/
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>>16576989
>the two circuits are trying to push in opposite directions
Holy fucking aneurism.
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>>16576989
Are u retarded? This explains nothing about what I’m asking. You don’t think maybe I already read where it came from??
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Equivelant circuit: two 1.5batteries in series, then two lamps in series. Then extra wire from between batteries to between lamps
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>>16576362
>If the load is balanced, you can completely cut the neutral and it changes none of the currents
Cutting the neutral turns it into a 240 volt circuit with each half in series. The reason that's fine if there's a balanced load is that you double the voltage but also double the resistance. If there's a load imbalance, then that's no longer true.
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Cold Take: As someone that had to do a bunch of electrical work on a house that had more than a dozen unlabeled multi-wire branch circuits, ended up working on shared neutrals that would have been carrying load had the wrong switch been flipped, and seeing the mess of a breaker box we were left with after we found out it needed replacing filled with tied together breakers all over the fucking place, FUCK multi-wire branch circuits and anyone that uses them. From what the electricians said they aren't even that common and they made working with the system annoying as all fuck.

It's fucking horrifying to me that some idiot removing a tiny piece of plastic before the next person comes along is all it takes to potentially get someone electrocuted or a circuit fried.

You shouldn't use these just for the dropped neutral risk alone. Just run the extra god damn wire.
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>>16577088
Right, but if your theory was that they run in series when balanced, you would say cutting the neutral did nothing because they were in series before. When do the differences matter?

Does the possibility of an imbalance disprove the series circuit model? Like if the top circuit was 12A and the bottom 10A, is it reasonable to say that from the 12A, 10 go to the bottom in series and 2 to the neutral?
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>>16576926
>I'm asking how you prove one or the other.
Use Kirchhoff's laws (no charge free of charge at junctions, no free energy by dragging charge through loop)? Or do you want some explanation going from quantum field theory or what?
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>>16577151
>they were in series before
They aren't. They both connect to ground in parallel.

>Like if the top circuit was 12A and the bottom 10A, is it reasonable to say that from the 12A, 10 go to the bottom in series and 2 to the neutral?
Yes. Not only is that reasonable to assume, that's exactly how it works.
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>>16577153
No that’s fine…so using kirchoff’s and looking at each circuit individually, I get that each side will flow back on the neutral and currents cancel. Is this the correct solution or did I do something wrong?

>>16577160
You seem to be saying different things. If they weren’t in series before, then they both flow together on the neutral and cancel. But then on the line you seem to say 10A flow in series, and 2A on the neutral.
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>>16575129
Think of it like this, if top and bottom are perfectly out of phase and have the same magnitud and the lamps have the same resistancs, then the situation is symmetrical around the neutral. Therefore, every tiny amount of charge that goes into the circuit by the top wire is sucked out of the circuit it by the bottom wire. Thus no current flows in the neutral. Whats depicted in your circuit are the mesh currents which may or may not be equal to the branch current ie what actually flows through the lamps . Mesh currents are a mathematical tool branch current it's what is actually flowing through a component.
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>>16577178
>But then on the line you seem to say 10A flow in series, and 2A on the neutral
Current in=current out with any circuit configuration



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