Absorption current
Updated 2026-10-27
Data records
- Absorption current, also called polarization current, is the component of the current drawn by insulation under direct voltage that decays slowly as the molecules of the dielectric align with the applied field. It is the reason an insulation resistance reading on sound insulation keeps rising for minutes after the voltage is applied.
- In timed insulation tests the absorption current falls more slowly than the capacitive charging current, and on good insulation the displayed resistance keeps rising as the charging currents disappear. On poor insulation a high leakage current hides the charging currents, so a graph of resistance against time is much flatter.
Elsewhere in the family
- Insulation Resistance related entry on Circuit Breaker Reference
- Insulation Resistance related entry on Electrical Testing Reference
- Insulation Resistance related entry on Motor Testing Reference
- Insulation Resistance related entry on Protective Relay Reference
- Insulation Resistance related entry on Revenue Metering Reference
- Insulation Resistance related entry on Switchgear Testing Reference
- Insulation Resistance related entry on Transformer Testing Reference
- Polarization Index and Dielectric Absorption related entry on Electrical Testing Reference
- Polarization Index and Dielectric Absorption related entry on Transformer Testing 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.
- Megger Electrical Tester article, Insulation testing diagnostic techniques, 2008-10-16 edition, Megger. Held as: Public page. Publisher page
Changelog (4 entries)
| Date | Revision | Change |
|---|---|---|
| 2026-10-27 | created (gloss.absorption-current.definition) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (gloss.absorption-current.definition) | |
| 2026-10-27 | created (gloss.absorption-current.usage) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (gloss.absorption-current.usage) |
Cite this page
Cite the governing standard for the fact itself; cite this page as the finding aid.
"Absorption current." Test Instrument Reference. 2026-10-27. https://www.testinstrumentreference.com/glossary/absorption-current/.
Test Instrument Reference, Absorption current (Oct. 27, 2026), https://www.testinstrumentreference.com/glossary/absorption-current/.
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title = {Absorption current},
howpublished = {\url{https://www.testinstrumentreference.com/glossary/absorption-current/}},
organization = {Test Instrument Reference},
publisher = {Test Instrument Reference},
year = {2026},
note = {last substantive change 2026-10-27}
}{{cite web |title=Absorption current |website=Test Instrument Reference |publisher=Test Instrument Reference |url=https://www.testinstrumentreference.com/glossary/absorption-current/ |date=2026-10-27 |access-date=}}