Rphase

Rphase is a term used to denote one of the three electrical phases in a polyphase power system. In many wiring schemes the three conductors are labeled R, S, and T (or sometimes U, V, W; some standards also use L1–L3). The R-phase is commonly associated with the red conductor in older color codes and serves as one leg of the balanced three-phase set.

In a balanced three-phase system, the phase voltages are separated by 120 degrees. If the R-phase voltage to neutral is VRN(t) = Vm sin(ωt), then the S- and T-phases lead or lag by 120 degrees, typically written as VSN(t) = Vm sin(ωt − 120°) and VTN(t) = Vm sin(ωt − 240°). The line-to-line voltages, which are often what motors and transformers experience, are related to these phase-to-neutral voltages by standard relationships (for example, the magnitude of a line-to-line voltage is √3 times the phase-to-neutral voltage in a balanced wye-connected system). The order in which the phases reach their maxima defines the phase sequence, such as R–S–T.

Rphase appears in schematics, switchgear, motor control, and generation equipment to identify one of the three phases. Its designation is regional and context-dependent; some regions use R, S, T, while others use L1, L2, L3 or color-coded labels. While “Rphase” is primarily a technical term in electrical engineering, the exact labeling can vary by standard and country.

Outside electrical engineering, the string “Rphase” may be used as a brand name or project identifier, but in technical literature it most often refers to the R-phase of a three-phase system.