Practice question

What is 'Total Harmonic Distortion' (THD) and what is the maximum THD typically allowed for LED drivers?

  1. THD is unrelated to lighting; it measures sound distortion
  2. THD measures the harmonic content as a percentage of the fundamental frequency; LED drivers should have less than 20% THD per Energy Star requirements
  3. THD is the total hours of darkness per year
  4. THD measures the total heat dissipated by the driver

Answer: B — THD measures the harmonic content as a percentage of the fundamental frequency; LED drivers should have less than 20% THD per Energy Star requirements

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