US4425949A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for removing undesirable substances from electrical devices
Assignee: Diamond Shamrock Chemicals Co
•
Filing: 1982-02-01
•
Granted: 1984-01-17
•
Expires: 2002-02-01
Abstract
Abstract The removal of undesirable substances such as water, PCB's and air from the internal components of electrical devices such as transformers and power capacitors is efficiently and effectively achieved by contacting, in the absence of air, the internal components of these various electrical devices with a heat-stable fluid material. The heat-stable fluid materials are preferably halogenated aliphatic hydrocarbons and most preferably perchloroethylene or FREON 113.
Inventors
- 👤 Edward A. Rowe, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:26
CPC Classifications
C; C10; C10G; C10G21/00; C10G21/006; H; H01; H01F; H01F27/00; H01F27/08; H01F27/10; H01F27/12; H01F27/14
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
92 words
A method for retrofilling a transformer which contains polychlorinated biphenyls and other undesirable substances comprising: (A) evacuating said transformer to about one millimeter Hg; (B) introducing a halogenated aliphatic hydrocarbon vapor into said transformer removing that vapor which is not adsorbed or condensed by the transformer, such that PCBs are removed along with said vapor until the outlet vapor temperature equals the inlet vapor temperature; (C) discontinuing introduction of said halogenated aliphatic hydrocarbon; (D) evacuating said transformer to about 20 millimeters Hg; and (E) filling said evacuated transformer with a dielectric material.
Claim 2
Independent Claim
92 words
A method for retrofilling a transformer which contains polychlorinated biphenyls and other undesirable substances comprising: (A) evacuating said transformer to about one millimeter Hg; (B) introducing a halogenated aliphatic hydrocarbon vapor into said transformer removing that vapor which is not adsorbed or condensed by the transformer, such that PCBs are removed along with said vapor until the outlet vapor temperature equals the inlet vapor temperature; (C) discontinuing introduction of said halogenated aliphatic hydrocarbon; (D) evacuating said transformer to about 20 millimeters Hg; and (E) filling said evacuated transformer with a dielectric material.
Claim 3
Dependent Claim
65 words
The method according to claim 1 wherein a transformer core is contacted with a halogenated aliphatic hydrocarbon vapor under reduced pressure and said contacting is continued until said transformer is saturated with said aliphatic hydrocarbon vapor at which point said contacting is discontinued and the halogenated aliphatic hydrocarbon vapor containing water and air and other undesirable substances is removed from said transformer under reduced pressure.
Claim 4
Dependent Claim
16 words
The method according to claim 1 wherein said halogenated aliphatic hydrocarbon is a chlorinated aliphatic hydrocarbon.
Claim 5
Dependent Claim
13 words
The method according to claim 3 wherein said chlorinated aliphatic hydrocarbon is perchloroethylene.
Claim 6
Dependent Claim
12 words
The method according to claim 1 wherein said dielectric material is perchloroethylene.
Claim 7
Dependent Claim
13 words
The method according to claim 1 wherein said halogenated aliphatic hydrocarbon is 1,1,2-trichloro-1,2,2-trifluoroethane.
Claim 8
Dependent Claim
17 words
The method according to claim 1 wherein steps (A)-(C) are repeated for at least one additional cycle.
Claim 9
Dependent Claim
35 words
The method according to claim 1 wherein water, air and other undesirable substances are separated from the halogenated aliphatic hydrocarbon vapor removed from said transformer and the separated halogenated aliphatic hydrocarbon is recycled for reuse.
Claim 10
Dependent Claim
26 words
The method according to claim 1 wherein the halogenated aliphatic hydrocarbon vapor contacting procedure is followed by at least one hot halogenated aliphatic hydrocarbon liquid flush.
Claim 11
Dependent Claim
23 words
The method according to claim 1 wherein the polychlorinated biphenyls concentration level within the transformer core is reduced to less than 50 ppm.
Claim 12
Dependent Claim
23 words
The method according to claim 1 wherein the polychlorinated biphenyls concentration level within the transformer core is reduced to less than 10 ppm.
Claim 13
Dependent Claim
28 words
A transformer core of a retrofilled transformer wherein the concentration level of polychlorinated biphenyls has been reduced to less than 50 ppm by the process of claim 1.
References Cited (Backward Citations)
US1931373A
Cited
US1866346A
Cited
GB358872A
Cited
US1966901A
Cited
US1953216A
Cited
US2019338A
Cited
US2139948A
Cited
US3485659A
Cited
US3957531A
Cited
US3733218A
Cited
US4054036A
Cited
US4177156A
Cited
US4276530A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-01-16 | 1987-07-18 | 1988-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-16 | 1991-07-18 | 1992-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-16 | 1995-07-18 | 1996-01-17 | $7700.00 | Window Closed / Lapsed |