Total harmonic distortion (THD)
Updated 2026-10-27
Data records
- IEEE 1159-2019 cautions that a current total harmonic distortion figure can mislead, since an adjustable speed drive at light load shows a high percentage while the rms harmonic current is low, and that a complete spectrum with magnitudes and phase angles characterizes harmonic distortion more fully.
- IEEE 519-2022 defines total harmonic distortion as the ratio of the rms of the harmonic content, up to a maximum harmonic order stated in the definition and excluding interharmonics, to the fundamental, expressed as a percent; the only difference from total demand distortion is the denominator.
Elsewhere in the family
- Total harmonic distortion (THD) more on this entry on Test Instrument Reference
- True RMS related entry on Test Instrument Reference
- Crest factor related entry on Test Instrument Reference
- Power quality analyzer related entry on Test Instrument Reference
- Power analyzer related entry on Test Instrument Reference
- Protective relay test set related entry on Test Instrument Reference
- Motor circuit analyzer related entry on Test Instrument Reference
- Electromagnetic compatibility (EMC) - Part 4-30: Testing and measurement techniques - Power quality measurement methods related entry on Test Instrument Reference
- Electrical safety in low voltage distribution systems up to 1 000 V AC and 1 500 V DC - Equipment for testing, measuring or monitoring of protective measures - Part 12: Power metering and monitoring devices (PMD) related entry on Test Instrument Reference
Sources
- IEEE 1159-2019, Recommended Practice for Monitoring Electric Power Quality, 2019 edition, IEEE. Cited: clause 4.4.5.2. Held as: Purchased single-user copy. Publisher page for IEEE 1159-2019Publisher information page
- IEEE 519-2022, Harmonic Control in Electric Power Systems, 2022 edition, IEEE. Cited: clause 3.1. Held as: Purchased single-user copy. Publisher page for IEEE 519-2022Publisher information page
Obtaining the documents
- IEEE 1159-2019: available from the publisher
- IEEE 519-2022: available from the publisher
Changelog (2 entries)
| Date | Revision | Change |
|---|---|---|
| 2026-10-27 | created (gloss.total-harmonic-distortion.ieee1159.light-load) | |
| 2026-10-27 | created (gloss.total-harmonic-distortion.ieee519.definition) |
Cite this page
Cite the governing standard for the fact itself; cite this page as the finding aid.
"Total harmonic distortion (THD)." Power Quality Reference. 2026-10-27. https://www.powerqualityreference.com/glossary/total-harmonic-distortion/.
Power Quality Reference, Total harmonic distortion (THD) (Oct. 27, 2026), https://www.powerqualityreference.com/glossary/total-harmonic-distortion/.
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howpublished = {\url{https://www.powerqualityreference.com/glossary/total-harmonic-distortion/}},
organization = {Power Quality Reference},
publisher = {Power Quality Reference},
year = {2026},
note = {last substantive change 2026-10-27}
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