Hello Avenger2016, Let's clear up the picture. Answering the questions of your first comment: Three-phase system: L1-L2-L3, each phase is 120º out of phase, in Argentina the typical values for a three-phase distribution are 3X380 Vac-50HZ Three-phase + Neutral System: [color=#333333] L1-L2-L3 + N, here also each phase is 120º out of phase, in Argentina the typical values for a three-phase distribution are 3X380VAC. + N -50HZ Single-phase system: It is that system with which 220 Vac-50Hz can be obtained, with any of the three phases and the Neutral, for example L1 + N. Biphasic System: It is that system which takes two phases to feed the loads, for example L1, and L2. It is not at all common to find this type of distributions, a case is in special installations where there is a neutral IT regime, that is to say where the Neutral is not distributed, which is why 3x380Vca primary transformers are installed, and 3x220vca of secondary. With respect to your second comment, if you only have one phase (L1) to power the primary of that transformer, surely the other power conductor is the Neutral. Now, in the secondary of this transformer, you only have two cables, in which you are going to measure between 220VAC (SINGLE PHASE) therefore you have no way of having a phase shift in the output cables of that transformer. Finally I tell you that 380Vca. It is low voltage (BT). I hope I have interpreted your question, and given you the answer you are looking for. Regards, Omar. [/Color]