Patent US3754675A successfully refreshed from Google Patents.
Patent US4470898A successfully refreshed from Google Patents.
US4470898A
Expired / Lapsed
US
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Polymer compositions for electrical use
Assignee: Raychem Ltd
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Filing: 1978-05-11
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Granted: 1984-09-11
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Expires: 1998-05-11
Abstract
Abstract Novel polymeric compositions having non-linear resistance characteristics, together with electrical equipment comprising such compositions. Any polymer may be used; the polymer contains substantial proportions of certain particulate fillers of a given structure, for example the perovskite and spinel structures.
Inventors
- 👤 Richard J. Penneck
- 👤 Paul Taylor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:53
CPC Classifications
H; H02; H02G; H02G15/00; H02G15/02; H02G15/06; H02G15/064; H02G15/068; H01; H01B; H01B3/00; H01B3/002; H01B3/004; H01B3/006
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
132 words
In a high voltage electrical apparatus subject to electrical stress, the improvement comprising providing relief against said stress by a composition exhibiting a nonlinear electrical resistance with variation in voltage, said composition comprising a thermoplastic or elastomeric polymer having dispersed therein at least one particulate filler compound selected from the group consisting of: (a) compounds having a perovskite type crystal structure; (b) metal oxides and mixed metal oxides having an inverse spinel-type crystal structure; and (c) metal oxides and mixed metal oxides having a mixed spinel-type crystal structure, the total weight of said particulate compound or compounds being at least 10% based on the weight of the polymer and such as to give the composition a gamma value of at least 1.5 at some direct current stress between 0.01 and 10 kV/mm.
Claim 2
Dependent Claim
132 words
In a high voltage electrical apparatus subject to electrical stress, the improvement comprising providing relief against said stress by a composition exhibiting a nonlinear electrical resistance with variation in voltage, said composition comprising a thermoplastic or elastomeric polymer having dispersed therein at least one particulate filler compound selected from the group consisting of: (a) compounds having a perovskite type crystal structure; (b) metal oxides and mixed metal oxides having an inverse spinel-type crystal structure; and (c) metal oxides and mixed metal oxides having a mixed spinel-type crystal structure, the total weight of said particulate compound or compounds being at least 10% based on the weight of the polymer and such as to give the composition a gamma value of at least 1.5 at some direct current stress between 0.01 and 10 kV/mm.
Claim 3
Dependent Claim
20 words
An apparatus as claimed in claim 1 wherein the particulate filler comprises stoichiometric or non-stoichiometric Fe 3 O 4 .
Claim 4
Dependent Claim
24 words
An apparatus according to claim 2 wherein the filler is non-stoichiometric Fe 3 O 4 and comprises Fe 2 O 3 , 0.8 FeO.
Claim 5
Dependent Claim
23 words
An article according to claim 2 wherein the filler comprises a mixture of Fe 3 O 4 and Co 3 O 4 .
Claim 6
Dependent Claim
23 words
An article according to claim 3 wherein the filler comprises a mixture of Fe 3 O 4 and Co 3 O 4 .
Claim 7
Dependent Claim
20 words
An article according to claim 2 wherein the filler comprises a mixture of Fe 3 O 4 and barium titanate.
Claim 8
Dependent Claim
20 words
An article according to claim 3 wherein the filler comprises a mixture of Fe 3 O 4 and barium titanate.
Claim 9
Dependent Claim
21 words
An article according to claim 2 wherein the filler comprises a mixture of Fe 3 O 4 and MoS 2 .
Claim 10
Dependent Claim
21 words
An article according to claim 2 wherein the filler comprises a mixture of Fe 3 O 4 and MoS 2 .
Claim 11
Dependent Claim
35 words
An article according to claim 1 wherein the filler comprises a sintered blend of substantially 50% by weight Cr 2 O 3 , 40% by weight Fe 2 O 3 and 10% by weight CuO.
Claim 12
Dependent Claim
18 words
An article according to claim 1 wherein the filler comprises a mixed oxide of iron, cobalt and nickel.
Claim 13
Dependent Claim
24 words
An article according to claim 1 wherein the filler comprises a synthetic magnetite comprising substantially 22% FeO and 77% Fe 2 O 3 .
Claim 14
Dependent Claim
24 words
An article according to claim 1 wherein the particulate filler is selected from the group consisting of strontium titanate, barium stannate and barium titanate.
Claim 15
Dependent Claim
22 words
An article according to claim 1 wherein the particulate filler is present in admixture with one or more particulate electrically conductive fillers.
Claim 16
Dependent Claim
26 words
An article according to claim 14 wherein the conductive filler is carbon black and the weight ratio of carbon black to polymer is at most 40:100.
Claim 17
Dependent Claim
27 words
An article according to claim 14 wherein the conductive filler is a metal powder and the weight ratio of metal powder to polymer is at most 100:100.
Claim 18
Dependent Claim
13 words
An article according to claim 14 wherein the metal powder is aluminum powder.
Claim 19
Dependent Claim
20 words
An article according to claim 14 wherein the filler comprises Fe 3 O 4 in admixture with a metal powder.
Claim 20
Dependent Claim
27 words
An article according to claim 18 wherein the metal powder is selected from the group consisting of iron, aluminum, copper, manganese, chromium, lead, nickel, zinc and silver.
Claim 21
Dependent Claim
19 words
An article according to claim 14 wherein the filler comprises Fe 3 O 4 in admixture with carbon black.
Claim 22
Dependent Claim
17 words
An article according to claim 14 wherein the filler comprises barium titanate in admixture with carbon black.
Claim 23
Dependent Claim
17 words
An article according to claim 1 wherein the particulate filler is present in admixture with silicon carbide.
Claim 24
Dependent Claim
17 words
An article according to claim 1 wherein the particulate filler is present in admixture with molybdenum disulphide.
Claim 25
Dependent Claim
19 words
An article according to claim 1 wherein the particle size of the particulate filler is less than 20 microns.
Claim 26
Dependent Claim
16 words
An article according to claim 24 wherein the said particle size is less than 5 microns.
Claim 27
Dependent Claim
27 words
An article according to claim 1 wherein the composition has a gamma value of at least 1.5 at a direct current stress between 0.1 and 5 kV/mm.
Claim 28
Dependent Claim
13 words
An article according to claim 1 wherein the polymer is an ethylene/propylene copolymer.
Claim 29
Dependent Claim
11 words
An article according to claim 1 wherein the polymer is cross-linked.
Claim 30
Dependent Claim
12 words
An article according to claim 1 wherein said composition is dimensionally unstable.
Claim 31
Dependent Claim
11 words
An article according to claim 29 wherein said composition is heat-shrinkable.
Claim 32
Dependent Claim
11 words
An article according to claim 1 which is an electric cable.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-09-11 | 1988-03-12 | 1988-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-11 | 1992-03-12 | 1992-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-11 | 1996-03-12 | 1996-09-11 | $7700.00 | Window Closed / Lapsed |