Patent US3896406A successfully refreshed from Google Patents.
US3896406A
Expired / Lapsed
US
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Screen for core legs for transformers, reactors and the like
Assignee: ABB Norden Holding AB
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Filing: 1974-08-06
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Granted: 1975-07-22
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Expires: 1994-08-06
Abstract
Abstract In order to prevent the occurrence of glow discharge at sharp corners and edges of core legs for transformers, reactors and the like which are formed of a plurality of sheets, tape is wound around the bundle of sheets, the tape being formed of a backing of glass fiber or the like having high mechanical strength and impregnated with an electrically semi-conducting and thermosetting material, the successive turns of tape overlapping, the winding being under high tension, the screen after heat treatment and curing being quite stiff and having good mechanical and electrical contact with the core leg along its longitudinal edges.
Inventors
- 👤 Olle Andersson
- 👤 Ellerth Ericsson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:56
CPC Classifications
H; H01; H01F; H01F27/00; H01F27/24; H01F27/245; H01F27/34; H01F27/36; H01F27/363
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
125 words
A core leg for transformers, reactors and the like formed of a plurality of magnetic sheets with a surrounding tape to prevent the occurrence of glow discharge at sharp corners and edges where there prevail inhomogeneous electric fields and to hold the core sheets together mechanically, said tape (1) comprising a backing having high mechanical strength and impregnated with an impregnant consisting essentially of an electrically semiconducting and thermosetting material, wound around the sheets with high mechanical tension and with overlapping so that a screen surrounding the core leg (2) is formed, said screen being cured by heat treatment and being quite stiff and having good mechanical and electrical contact with the core leg at least along the longitudinal edges (3) of the core leg.
Claim 2
Dependent Claim
125 words
A core leg for transformers, reactors and the like formed of a plurality of magnetic sheets with a surrounding tape to prevent the occurrence of glow discharge at sharp corners and edges where there prevail inhomogeneous electric fields and to hold the core sheets together mechanically, said tape (1) comprising a backing having high mechanical strength and impregnated with an impregnant consisting essentially of an electrically semiconducting and thermosetting material, wound around the sheets with high mechanical tension and with overlapping so that a screen surrounding the core leg (2) is formed, said screen being cured by heat treatment and being quite stiff and having good mechanical and electrical contact with the core leg at least along the longitudinal edges (3) of the core leg.
Claim 3
Dependent Claim
23 words
A core leg according to claim 1, in which the backing of the tape (1) consists essentially of a fabric of glass fiber.
Claim 4
Dependent Claim
21 words
A core leg according to claim 1, in which the material properties of the tape can be expressed in the formula:
References Cited (Backward Citations)
US2399314A
Cited
US2705292A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-07-21 | 1979-01-20 | 1979-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-21 | 1983-01-20 | 1983-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-21 | 1987-01-20 | 1987-07-22 | $7700.00 | Window Closed / Lapsed |