Power Calculations for Distorted Waveforms

Figure 1: The sum of many sine waves, of varying
amplitudes and frequencies, comprises the rough-
looking square wave shown in red

Our last post covered basic power calculations for pure sine waves, which are useful only up to a point in that pure sine waves are rather rare in the real world. Almost any real-world waveform carries some amount of distortion. Because distorted voltage and current waveforms comprise multiple frequencies, the relatively simple techniques used to measure power for pure, single-frequency sine waves no longer apply.

Back to Basics: Fundamentals of AC Line Power (Part II)

Figure 1: AC line voltage is a single-phase
vector that rotates at a given frequency

Having reviewed a broad definition of power, how it is generated and distributed, and how motors consume almost half of all generated power, we will now turn to a more detailed discussion of just what it is that we call "power." When we discuss "power," we're typically referring to what comes out of a wall socket: AC line, or sinusoidal, power.