The return current of nonlinear loads can cause what kind of distortion in the voltage waveform?

• A. Voltage sag
• B. Voltage swell
• C. No distortion
• D. Harmonic distortion

Answer: (D)

Nonlinear loads draw current that isn’t a pure sine wave, so the current contains harmonics—multiples of the fundamental frequency. When this harmonic current flows through the supply and through any line or neutral impedance, each harmonic component causes a corresponding voltage component. The result is a voltage waveform that deviates from a pure sine due to these added harmonic voltages. This is harmonic distortion. Voltage sag or swell describe changes in voltage magnitude, not the presence of harmonics, and no distortion would imply a clean sine, which isn’t the case here.