Hello I looked for a good forum which I can use for my specific questions. I hope I am right here. English is unfortunately not my first language, but I am working on improving it. So please have understanding for it. I need help in three phase drive technology. I read in my book that power is defined by p1 = u*i = u*sin(wt+phi)*i*sin(wt) Now I ask myself why the first term of sin() contains a +phi and the second term does not. I mean in the star connection for example u and i have an angular phase shift. So why is also in the second term not a +phi?