Does phase voltage lead or lag line voltage?
Yes, this is confusing. But the confusion arises out of the use of non-specific terminology. A three phase system has three phase-to-neutral voltages that are (usually) equal in magnitude and displaced by 120 electrical degrees. These are sometimes casually referred to as ‘phase voltages’ (although ‘phase-to-neutral voltage’ is a better term.) A three-phase system also has three phase-to-phase voltages that are also (usually) equal in magnitude and displaced by 120 electrical degrees. These voltages either lead or lag the phase-to-neutral voltages depending on which phase-to-neutral voltage you choose as reference and how you define phase-to-phase voltage (ie, phase A-B voltage is numerically equal to phase B-A voltage, but they are 180 degrees out of phase with each other). The term “line voltage” is sometimes carelessly equated with the more exact term ‘phase-to-phase voltage’. So, bottom line is that once you get a clear definition of what you mean by the terms you are using, and al
