I have been wondering this for a while now, and haven’t really found any answers that I understood. The way I think of it is that when you measure voltage from line to neutral you are kind of measuring “halfways from” the winding of L1 (where you only measure over one winding) to the shared point of the other phases instead of when you measure from line to line and you measure over both the windings in between them.
Tl;dr In a 230V distribution, why does measuring from line to line give 230V but line to neutral gives 120-130? And why the magical number sqr(3)? In my mind it should be 0.5 .. :p
Bonus question: Does anyone have a physical picture of how the transformer is connected to the consumer? I have seen the diagram, but I’m wondering what the cabling looks like in real life
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The three wires are a 3 phase connection. Now electrical phases are offset by TIME. And this can be hard to imagine without looking at the sine waves and doing a bit of trigonometry.
But an equivalent situation is to take three sticks each 120 mm long. (you can maybe say that each mm represents 1 volt). Now arrange it in a “star” pattern, ie each stick has one end at the center pointing outwards but each stick is rotated 120 degrees from each other. (it will look like a Y).
Now the phase to phase voltage is measured by drawing a straight line from the end of one stick to the end of the next stick. The length of that line in mm tells you the phase to phase voltage. It should be immediately apparent that the line isn’t 120+120 mm long since the sticks are not pointing in directly opposite directions. It is indeed shorter and if you measure it you should get (120+120)/sqrt(3).
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