What causes harmonic distortion and what issues may result?

• A. Distortion of waveforms caused by linear loads; can cause overheating.
• B. Distortion of waveforms caused by non-linear loads; has no significant effect.
• C. Distortion of waveforms caused by non-linear loads; can cause overheating and PF issues.
• D. Distortion of waveforms caused by balanced loads; no distortion occurs.

Answer: (C)

Harmonic distortion happens when the current or voltage contains frequencies other than the fundamental line frequency, usually due to non-linear loads that draw current in pulses rather than a smooth sine wave. This distorted waveform can cause heating in electrical equipment because the harmonic currents add to the fundamental current and increase I²R losses in conductors, transformers, and motors. It also disturbs the power factor, often reducing it and leading to more current for the same amount of useful work, which can exacerbate overheating and cause voltage regulation problems. Non-linear devices such as rectifiers, switching power supplies, and variable-frequency drives are common sources. Linear or balanced loads don’t generate this distortion, so they don’t produce these issues.