I kind of understand that now, my question was like why theres 48v dc on the phoneline in the front and 230v on each phase, haha.Semantics.
"If each phase is 230..." Only as measured from line to Neutral
"... how come its 400v across phases?" Only as measured Phase to Phase.
Apples and Oranges.
Well, actually Apples and Crabapples might be a better analogy.
Pick a spot in a field and drive a stake, call it "A", walk 231 paces and drive another stake and call it "X", now turn 120 degrees and walk 231 paces drive another stake and call it "B", now walking in a straight line count the paces between "A" and "B"
This is what the sine waves look like for a three-phase system (the gray line is neutral, 0 volts):
Watch a dot on any phase. When one of the phases is at the peak on the wave (maximum voltage) you can see that the other two phases are always gonna be at lower positions (lower voltages).
That is because of how they are generated: When the field on the generator has maximum influence over the winding in "A" phase and is generating the most potential in that winding, it has less of an influence over "B" and "C". And that's true for the other ones as well, when each winding is at maximum voltage, the others are at less potential. These windings are spaced evenly apart within the generator so this peak influence on each on occurs 120° out of phase (360° ÷ 3).
With a three-phase transformer, the windings are also spaced 120° apart, so they mimic the voltages present on the generator.
That means you are measuring peak L-N voltage on "B" phase, the L-N voltage at that same time on "A" or "C" phase are not at their peaks:
("A" and "C" are actually both the same position at that red dot.)
So even though the RMS voltage on any one phase to neutral is 120V, when you measure across them you're not adding 120V+120V because the actual RMS voltages at any single time are much closer to 120V+88V or 208V.