EP0875087B1
Expired / Lapsed
EP
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Electrical stress control
Assignee: Tyco Electronics Raychem GmbH
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Filing: 1997-01-14
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Granted: 2000-11-29
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Expires: 2017-01-14
Abstract
Abstract PCT No. PCT/GB97/00092 Sec. 371 Date Sep. 17, 1998 Sec. 102(e) Date Sep. 17, 1998 PCT Filed Jan. 14, 1997 PCT Pub. No. WO97/26693 PCT Pub. Date Jul. 24, 1997A composition for use as an electrical stress controlling layer (12) for use with cable joints and terminations has a non-linear V-I characteristic. The composition comprises a polymeric matrix filled with doped zinc oxide varistor powder. The particulate filler is sieved at 125 micrometers, calcined at 1100 DEG C., and lightly ground to maintain the spherical shape of the particles. More than 50% by weight of the particles have a maximum dimension between 5 and 100 micrometers.
Inventors
- 👤 Christian Kemp
- 👤 Georg Bachmaier
- 👤 Hansjoerg Gramespacher
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 01:01
CPC Classifications
H; H02; H02G; H02G15/00; H02G15/02; H02G15/06; H02G15/064; H02G15/068; H02G15/08; H02G15/18; H02G15/184; H02G15/188; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2913; Y10T428/2933; Y10T428/294; Y10T428/2958; Y10T428/31504; Y10T428/31511; Y10T428/31515; Y10T428/31522; Y10T428/31529; Y10T428/31678; Y10T428/31692; Y10T428/31699
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
145 words
An electrical stress-controlling composition, comprising : (a) a polymeric matrix, and (b) a particulate filler comprising doped zinc oxide varistor powder; characterised in that (i) the particles of the filler are calcined at a temperature between 800°C
and 1400°C, and subsequently broken up such that substantially all of the
particles retain their original shape, (ii) at least 85% of the weight of the filler comprises zinc oxide, (iii) more than 50% by weight of the filler particles have a maximum
dimension of between 5 and 100 micrometres, such that the composition
exhibits non-linear electrical behaviour whereby its specific impedance
decreases by at least a factor of 10 when the electric field is increased by less
than 5kV/cm at a region within an electrical field range of 5kV/cm to
50kV/cm, and (iv) the filler comprises between 5% and 60% of the volume of the total
composition.
Claim 2
Dependent Claim
27 words
A composition according to claim 1, wherein all the particles of the filler have a
maximum dimension of less than 125 micrometres, preferably less than 100 micrometers.
Claim 3
Dependent Claim
28 words
A composition according to claim 1 or claim 2, wherein not more than 15% by
weight of the filler particles have a maximum dimension less than 15 micrometres.
Claim 4
Dependent Claim
27 words
A composition according to any one of the preceding claims, wherein the filler
particles are calcined at a temperature between 950°C and 1250°C, preferably at about
1100°C.
Claim 5
Dependent Claim
23 words
A composition according to any one of the preceding claims, wherein at least 90%
of the weight of the filler comprises zinc oxide.
Claim 6
Dependent Claim
30 words
A composition according to any one of the preceding claims, wherein more than
50% by weight of the filler particles have a maximum dimension of between 25 and 75
micrometres.
Claim 7
Dependent Claim
25 words
A composition according to any one of the preceding claims, wherein the filler
comprises between 10% and 40% of the volume of the total composition.
Claim 8
Dependent Claim
17 words
A layer of material comprising a stress-controlling composition in accordance with
any one of the preceding claims.
Claim 9
Dependent Claim
20 words
A joint or termination of an electric power cable having applied thereto a layer of
material according to claim 8.
References Cited (Backward Citations)
No citation records indexed.
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