Dielectric material with enhanced breakdown strength

Patent metadata

Field	Value
Publication number	US-10121570-B2
Application number	US-201515519399-A
Country	US
Kind code	B2
Filing date	Oct 14, 2015
Priority date	Oct 17, 2014
Publication date	Nov 6, 2018
Grant date	Nov 6, 2018

Abstract

An enhanced breakdown strength dielectric material includes a base dielectric layer having first and second opposing major surfaces. A first stress mitigating layer is disposed on the first major surface of the base dielectric layer. A second stress mitigating layer disposed on the second major surface of the base dielectric layer. A volume conductivity of at least one of the first and second stress mitigating layers is at least 2 times a volume conductivity of the base dielectric layer.

First claim

What is claimed is:

1. An enhanced breakdown strength dielectric material comprising:
a base dielectric layer having first and second opposing major surfaces,
a first stress mitigating layer disposed on the first major surface of the base dielectric layer, and
a second stress mitigating layer disposed on the second major surface of the base dielectric layer,
wherein a ratio of a volume conductivity of at least one of the first and second stress mitigating layers to a volume conductivity of the base dielectric layer is greater than or equal to 2, wherein each stress migrating layer comprises a molybdenum disulfide (MoS 2 ) filler material having a concentration of about 0.8% to about 12% by volume based on the total volume of the stress migrating layer.

2. The enhanced breakdown strength dielectric material of claim 1 , wherein the filler material is dispersed in a binder material.

3. The enhanced breakdown strength dielectric material of claim 2 , wherein the filler material comprises one or more particulates, each having a shape selected from spheres, plates, platelets, cubes, needles, oblate, spheroids, pyramids, prisms, flakes, rods, fibers, chips, whiskers, and mixtures thereof.

4. The enhanced breakdown strength dielectric material of claim 3 , wherein the size of each filler material particulate can be from about 10 nm to about 100 μm.

5. The enhanced breakdown strength dielectric material of claim 1 , wherein at least one of the first and second stress mitigating layers comprises a binder material, wherein the binder material comprises a polymer selected from the group consisting of silicone, poly(vinyl chloride), EPDM rubber, EPR, EVA, polyimide, fluoropolymers, epoxies, polysulfides, polyethylene, and polyester.

6. The enhanced breakdown strength dielectric material of claim 1 , wherein the base dielectric layer comprises a material selected from the group consisting of polymers and insulating materials.

7. The enhanced breakdown strength dielectric material of claim 1 , wherein each stress migrating layer has a volume conductivity from about 1 ×10 −12 S/m to about 1 ×10 −8 S/m.

8. A power cable, comprising:
a conductor;
a first shielding layer surrounding the conductor;
an insulation layer comprising the enhanced breakdown strength dielectric material of claim 1 ;
a second shielding layer surrounding the insulation layer; and
a protective jacket surrounding the second shielding layer.

9. A dielectric stress control device comprising a shaped body that includes an insulation layer comprising the enhanced breakdown strength dielectric material of claim 1 .

10. A mastic comprising the enhanced breakdown strength dielectric material of claim 1 .

11. A tape comprising the enhanced breakdown strength dielectric material of claim 1 .

12. An enhanced breakdown strength dielectric material comprising:
a base dielectric layer having first and second opposing major surfaces,
a first stress mitigating layer disposed on the first major surface of the base dielectric layer, and
a second stress mitigating layer disposed on the second major surface of the base dielectric layer,
wherein a ratio of a volume conductivity of at least one of the first and second stress mitigating layers to a volume conductivity of the base dielectric layer is greater than or equal to 2, wherein each stress migrating layer comprises a tungsten disulfide (WS2) filler material having a concentration of about 0.5% to about 16% by volume based on the total volume of the stress migrating layer.

13. A power cable, comprising:
a conductor;
a first shielding layer surrounding the conductor;
an insulation layer comprising the enhanced breakdown strength dielectric material of claim 12 ;
a second shielding layer surrounding the insulation layer; and
a protective jacket surrounding the second shielding layer.

14. A dielectric stress control device comprising a shaped body that includes an insulation layer comprising the enhanced breakdown strength dielectric material of claim 12 .

15. A mastic comprising the enhanced breakdown strength dielectric material of claim 12 .

16. A tape comprising the enhanced breakdown strength dielectric material of claim 12 .

Assignees

• 3M Innovative Properties Co

Inventors

• Somasiri Nanayakkara L D
• Huynh Paul V
• Lottes Andrew C
• Taylor William L
• Biyikli Levent
• Fisher Carl E

Classifications

• H01B3/443

  from vinylhalogenides or other halogenoethylenic compounds · CPC title

• H01B3/306 Primary

  Polyimides or polyesterimides · CPC title

• H01B9/021

  Features relating to screening tape per se · CPC title

• H01B3/46

  silicones · CPC title

• C09J2203/302

  for bundling cables · CPC title