chapter  5
39 Pages

Calculating Three-Phase Power

WithJoseph E. Fleckenstein

Power consumption calculations of a single, balanced three-phase circuit can be performed with relative ease. In contrast, the power of a three-phase circuit that feeds one or more unbalanced three-phase circuits can present a greater challenge. This chapter deals with the computations that will allow a person to complete the power calculations of any type of three-phase circuit, balanced or unbalanced. To calculate the power of a three-phase circuit, specific parameters must be known, voltage must be known. Also, the values of currents and the leads or lags of currents with respect to voltages are necessary. In a balanced three-phase wye circuit, the phase currents of all three phases are of the same magnitude as the line currents, and all three currents are at the same lead/lag angle. The values of root mean square current and root mean square voltage are helpful in determine the total power of linear systems.