继电保护原理与应用(第三版)3.1-3.5(5)

3.2.2 Phasor Diagrams for Sinusoidal Quantities正弦量的相量图
In applying the preceding notation to sinusoidal (AC) voltages, currents, and fluxes, the axes are assumed as fixed, with the phasor quantities rotating at a constant angular velocity. The international standard is that phasors always rotate in the counterclockwise direction. However, as a convenience, on the diagrams the phasor is always shown as fixed for the given condition. The magnitude of the phasor c can be either the maximum peak value or the rms value of the corresponding sinusoidal quantity. In normal practice, it represents the rms maximum value of the positive half-cycle of the sinusoid unless otherwise specifically stated.
在将上述符号应用于正弦（AC）电压、电流和通量时，假设轴是固定的，相量以恒定的角速度旋转。国际标准是相量总是逆时针旋转。然而，为了方便起见，在图表上，对于给定的条件，相量总是显示为固定的。相量c的大小可以是相应正弦量的最大峰值或均方根值。在正常实践中，除非另有特别说明，否则它表示正弦波正半周期的rms最大值。
Thus, a phasor diagram shows the respective voltages, currents, fluxes, and so on, existing in the electric circuit. It should document only the magnitude and relative phase-angle relations between these various quantities. Therefore, all phasor diagrams require a scale or complete indications of the physical magnitudes of the quantities shown. The phase-angle reference is usually between the quantities shown, so that the zero (or reference angle) may vary with convenience. As an example, in fault calculations using reactance X only, it is convenient to use the voltage V reference at 908. Then and the j value cancels, so the fault current does not involve the j factor. On the other hand, in load calculations it is preferable to use the voltage V at 08 or along the x-axis so that the angle of the current I represents its actual lag or lead value