Total harmonic distortion (THD)
Updated 2026-10-27
Data records
- Total harmonic distortion is the ratio of the root-mean-square value of all the harmonic components of a voltage or current to the root-mean-square value of its fundamental component, expressed as a percentage; it summarizes in one figure how far a waveform departs from a pure sine wave.
- The term is written Total harmonic distortion (THD). Value: Total harmonic distortion (THD).
- A power quality analyzer displays total harmonic distortion as a percentage, most often of the voltage, and shows the share of each individual harmonic as a harmonic spectrum either live on the instrument or from logged data; harmonics arise mainly from nonlinear loads such as variable frequency drives that draw current in abrupt pulses.
Elsewhere in the family
- Total harmonic distortion (THD) more on this entry on Power Quality Reference
- Power Quality and Harmonic Survey related entry on Power Quality Reference
- Harmonics related entry on Power Quality Reference
- Total harmonic distortion (THD) related entry on Power Quality Reference
- IEEE Standard for Harmonic Control in Electric Power Systems related entry on Power Quality Reference
- IEEE Recommended Practice for Monitoring Electric Power Quality related entry on Power Quality Reference
Sources
- Electrical Testing Reference editorial taxonomy, Electrical Testing Reference editorial taxonomy of test methods, 2026-10 edition, Electrical Testing Reference. Held as: Own observation.
- Fluke learn article, Causes and Effects of Harmonics in Electrical Power Systems, web page edition, Fluke. Held as: Public page. Publisher page
Changelog (6 entries)
| Date | Revision | Change |
|---|---|---|
| 2026-10-27 | created (gloss.total-harmonic-distortion.definition) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (gloss.total-harmonic-distortion.definition) | |
| 2026-10-27 | created (gloss.total-harmonic-distortion.title) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (gloss.total-harmonic-distortion.title) | |
| 2026-10-27 | created (gloss.total-harmonic-distortion.usage) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (gloss.total-harmonic-distortion.usage) |
Cite this page
Cite the governing standard for the fact itself; cite this page as the finding aid.
"Total harmonic distortion (THD)." Test Instrument Reference. 2026-10-27. https://www.testinstrumentreference.com/glossary/total-harmonic-distortion/.
Test Instrument Reference, Total harmonic distortion (THD) (Oct. 27, 2026), https://www.testinstrumentreference.com/glossary/total-harmonic-distortion/.
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title = {Total harmonic distortion (THD)},
howpublished = {\url{https://www.testinstrumentreference.com/glossary/total-harmonic-distortion/}},
organization = {Test Instrument Reference},
publisher = {Test Instrument Reference},
year = {2026},
note = {last substantive change 2026-10-27}
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