So let’s say that I have a three phase system has a current absorption on 30A. Are these 30A divided 10 per phase or are these 30A per phase, which brings the total to theoretically 90A?
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If the machine states it draws 30A, then it’s 10A per phase. If you measure current on a single wire and it shows 30A, then it’s 30A per phase for a total 90A
Can you add some context to your question? I did electrical design on industrial equipment and if the nameplate was marked 30A, that required a 3 phase supply with the capability of 30A on each phase.
If you are simply attaching an ammeter to a single phase, you will see the undivided amperage of the load. But keep in mind that although your meter is showing a seemingly constant current draw, the current distribution in the three phases is continuously changing. In any one or two conductors, the leaving current is same to the entering current in that conductor (or conductors). In other words, each conductor provides a return path to the currents of the other conductors. This way, current division is continuously changing in three lines.
There are different 3 phase systems possible, Star/Wye and Delta. Depending on which you use, the current is divided differently.
[https://en.wikipedia.org/wiki/Three-phase_electric_power](https://en.wikipedia.org/wiki/Three-phase_electric_power)
If the power draw is balanced between the phases, the current is the same in each phase.
However there are 3 phase loads that have widely different currents in each phase.
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