Ferroresonance in electricity networks
Open-knowledge reference entry
Ferroresonance, or nonlinear resonance, is a rare type of resonance in electric circuits which occurs when a circuit containing a nonlinear inductance is fed from a source that has series capacitance, and the circuit is subjected to a disturbance such as opening of a switch. It can cause overvoltages and overcurrents in an electrical power system and can pose a risk to transmission and distribution equipment and to operational personnel.
Ferroresonant effects were first described in a 1907 paper by Joseph Bethenod. The term ferroresonance was apparently coined by French engineer Paul Boucherot in a 1920 paper, in which he analysed the phenomenon of two stable fundamental frequency operating points coexisting in a series circuit containing a resistor, nonlinear inductor and a capacitor.
Technical description
In general, "attempts to set precise limits for prevention of the phenomenon have been frustrating", and no complete model of the underlying physics is known. However, ferroresonance generally occurs when a transformer driving a system with primarily reactive (large imaginary part) impedance experiences perturbation to a single electrical phase. The transformer must be operating close to its saturation point, at which a real transformer's leakage inductance decreases dramatically.
Following perturbation, the transformer oscillates in and out of the saturated and unsaturated modes of operation each cycle, such that the cycle-average inductance cancels out the power line impedance. In situations where the primary impedance on the line is the several-hundred-picofarad shunt capacitance to ground, the combined transformer-power line system effectively acts as a low-impedance fault.
A nonlinear oscillation, ferroresonance exhibits substantial differences from a classical LC circuit.
Begin with the source’s own compact description: “Ferroresonance in electricity networks” is open-knowledge reference entry. The dossier treats that line as a proposition to test through Ferroresonance, electricity and networks, not as a finished interpretation.
Why this record matters
The phrase “open-knowledge reference entry” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Nov 4, 2025. The linked authority identifier is Q1616769. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1907 and 1920.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Ferroresonance in electricity networks”, its source revision and the description used here.
- Expand the search: follow Ferroresonance in electricity networks primary sources, Ferroresonance in electricity networks archive and Ferroresonance research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Ferroresonance in electricity networks”?
- Which cited source is closest to the event, object or claim?
- What terminology or title could unlock a more precise catalogue search?
Search terms from this dossier
This entry incorporates text from “Ferroresonance in electricity networks” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.