Which load type is generally responsible for harmonics in power systems?

Which load type is generally responsible for harmonics in power systems?

• A. Resistive heating loads
• B. Incandescent lighting loads
• C. Non-linear loads
• D. Household cooking equipment

Answer: (C)

Harmonics arise when the current drawn by a load is not proportional to the voltage, causing distortion of the current waveform. In linear loads, current follows the voltage sinusoidally, so the flow contains mainly the fundamental frequency. Non-linear loads, such as switch-mode power supplies, electronic drivers, LED drivers, and variable frequency drives, draw current in sharp pulses or in a non-proportional way. Those abrupt current shapes introduce a spectrum of harmonic frequencies—multiples of the fundamental—into the power system, leading to distortion, heating, and communication or protection issues that utilities monitor and mitigate. Resistive heating loads and incandescent lighting are essentially linear; they draw current in step with the voltage and remain mostly sinusoidal, contributing little to harmonic distortion. Likewise, simple household cooking equipment that uses heating elements behaves similarly, so it’s not a primary source of harmonics.

Harmonics arise when the current drawn by a load is not proportional to the voltage, causing distortion of the current waveform. In linear loads, current follows the voltage sinusoidally, so the flow contains mainly the fundamental frequency. Non-linear loads, such as switch-mode power supplies, electronic drivers, LED drivers, and variable frequency drives, draw current in sharp pulses or in a non-proportional way. Those abrupt current shapes introduce a spectrum of harmonic frequencies—multiples of the fundamental—into the power system, leading to distortion, heating, and communication or protection issues that utilities monitor and mitigate.

Resistive heating loads and incandescent lighting are essentially linear; they draw current in step with the voltage and remain mostly sinusoidal, contributing little to harmonic distortion. Likewise, simple household cooking equipment that uses heating elements behaves similarly, so it’s not a primary source of harmonics.