Which device is commonly used to mitigate harmonic currents in a circuit?

Which device is commonly used to mitigate harmonic currents in a circuit?

• A. DC to AC inverter
• B. Step-up transformer
• C. Line reactor
• D. In-line capacitor

Answer: (C)

The thing being tested is how to reduce harmonic currents in a circuit. Harmonics come from non-linear loads that draw current in sharp, non-sinusoidal pulses. To damp those distortions, you want some impedance in series with the load to limit the higher-frequency components of the current. A line reactor provides inductive impedance in series, which smooths the current waveform and reduces the amount of harmonic current that can flow back into the supply. It also helps limit inrush and dv/dt effects, protecting equipment and improving power quality. Other options don’t address harmonics in the same way. A DC-to-AC inverter can introduce or require filtering for harmonics rather than mitigate them. A step-up transformer changes voltage without specifically reducing harmonics. An in-line capacitor improves power factor but can worsen harmonic resonance or amplify harmonic currents if not designed with harmonic control in mind.

The thing being tested is how to reduce harmonic currents in a circuit. Harmonics come from non-linear loads that draw current in sharp, non-sinusoidal pulses. To damp those distortions, you want some impedance in series with the load to limit the higher-frequency components of the current. A line reactor provides inductive impedance in series, which smooths the current waveform and reduces the amount of harmonic current that can flow back into the supply. It also helps limit inrush and dv/dt effects, protecting equipment and improving power quality.

Other options don’t address harmonics in the same way. A DC-to-AC inverter can introduce or require filtering for harmonics rather than mitigate them. A step-up transformer changes voltage without specifically reducing harmonics. An in-line capacitor improves power factor but can worsen harmonic resonance or amplify harmonic currents if not designed with harmonic control in mind.