Voltage imbalance
Updated 2026-10-27
Data records
- IEEE 1159-2019 attributes minor voltage imbalance mainly to unbalanced single-phase loads on a three-phase circuit, with capacitor bank fuse failures and single-phase regulators as other causes, and severe imbalance to single-phasing conditions such as an open upstream protective device.
- In IEEE 1159-2019 voltage or current imbalance is the ratio of the negative sequence component to the positive sequence component, usually expressed as a percentage, with unbalance as the synonym; Annex C also admits the zero sequence to positive sequence ratio.
- IEEE 1159-2019 warns that many measuring instruments compute imbalance by the ANSI C84.1 method, the maximum deviation of a phase-to-phase voltage from the average divided by the average, which agrees with the sequence ratio only when harmonic content is low and zero sequence is small.
Sources
- IEEE 1159-2019, Recommended Practice for Monitoring Electric Power Quality, 2019 edition, IEEE. Cited: clause 4.4.4; clause 3. Held as: Purchased single-user copy. Publisher page for IEEE 1159-2019Publisher information page
Obtaining the documents
- IEEE 1159-2019: available from the publisher
Changelog (3 entries)
| Date | Revision | Change |
|---|---|---|
| 2026-10-27 | created (gloss.voltage-imbalance.ieee1159.causes) | |
| 2026-10-27 | created (gloss.voltage-imbalance.ieee1159.definition) | |
| 2026-10-27 | created (gloss.voltage-imbalance.ieee1159.instrument-definition) |
Cite this page
Cite the governing standard for the fact itself; cite this page as the finding aid.
"Voltage imbalance." Power Quality Reference. 2026-10-27. https://www.powerqualityreference.com/glossary/voltage-imbalance/.
Power Quality Reference, Voltage imbalance (Oct. 27, 2026), https://www.powerqualityreference.com/glossary/voltage-imbalance/.
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howpublished = {\url{https://www.powerqualityreference.com/glossary/voltage-imbalance/}},
organization = {Power Quality Reference},
publisher = {Power Quality Reference},
year = {2026},
note = {last substantive change 2026-10-27}
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