Condenser bushing

Patent metadata

Field	Value
Publication number	US-12387859-B2
Application number	US-202017789969-A
Country	US
Kind code	B2
Filing date	Dec 22, 2020
Priority date	Dec 30, 2019
Publication date	Aug 12, 2025
Grant date	Aug 12, 2025

Abstract

The present disclosure relates to a condenser bushing including a condenser core and electrically conductive field-grading layers, which are embedded in insulating material of the condenser core and arranged around a central channel for conductor extending along an axis defining an axial direction, while an electric connection is provided to at least one of the field-grading layers, wherein pairs of neighbouring field-grading layers with the insulation material between them form sections of the condenser core of axial lengths L 1 through L n and with capacitances C 1 through C n , characterized in that a shape of at least one of the field-grading layers deviates from cylindricality in order to reduce non-uniformity of electric field stress of the condenser bushing compared to a corresponding condenser bushing with the cylindrical field-grading layers forming sections of the axial lengths L 1 through L n and with capacitances C 1 through C n .

First claim

The invention claimed is:

1. A condenser bushing comprising:
a condenser core and electrically conductive field-grading layers, which are embedded in insulating material of the condenser core and arranged around a central channel for a conductor extending along an axis defining an axial direction, an electric connection being provided to at least one of the field-grading layers,
pairs of neighbouring field-grading layers with the insulation material between them forming sections of the condenser core of axial lengths L 1 through L n and with capacitances C 1 through C n ,
a shape of at least one of the field-grading layers deviating from cylindricality to reduce non-uniformity of electric field stress of the condenser bushing compared to a corresponding condenser bushing with the cylindrical field-grading layers forming corresponding sections of the axial lengths L 1 through L n and with capacitances C 1 through C n , and
at least one of the field-grading layers being shaped such that the diameter of said field-grading layer varies along the axial direction, the diameter of said field grading layer having at least one maximum between the edges of the field-grading layer, wherein the maximums of the field-grading layers increase in amplitude along a radial direction, but narrower in width along the axial direction, with increasing distance from the condenser core, wherein the terminating ends of each of the field-grading layers are straight in the axial direction.

2. The condenser bushing according to claim 1 , wherein the mean edge field stress level, defined as the ratio of the voltage U i of one of the sections and the radial width δ i of the section at its end in at least one section formed by a non-cylindrical field-grading layer is smaller than in the corresponding section of a condenser bushing with cylindrical field-grading layers forming sections of identical capacitances C 1 through C n and identical axial lengths L 1 through L n .

3. The condenser bushing according to claim 2 , wherein the absolute value of

(

U
i

δ
⁢
i

/

U
j

δ
⁢
j

-
1

)

is at least 20% smaller than the absolute value of

(

U
i

δ
i
′

/

U
j

δ
j
′

-
1

)

,

where

U
i

δ
⁢
i

⁢

and

are the mean edge field stress levels of two neighbouring sections, wherein at least one section is formed by a non-cylindrical field-grading layer and

U
i

δ
i
′

⁢

and
⁢

U
j

δ
j
′

are the mean edge field stress levels of two corresponding neighbouring sections the corresponding condenser bushing with the cylindrical field-grading layers.

4. The condenser bushing according to claim 1 , wherein the radial widths of the sections at their axial ends are substantially equal.

5. The condenser bushing according to claim 1 , wherein the innermost and/or the outermost field-grading layer is cylindrical.

6. The condenser bushing according to claim 1 , wherein the capacitances of all the sections formed by the field-grading layers are equal.

7. The condenser bushing according to claim 1 , wherein at least one of a ground connection, the electrical connection, and/or a voltage-tap connection is an integral part of a field-grading layer and has a substantially axially symmetric shape, with a conductive material volume reaching from the field-grading layer to the outer or inner surface of the condenser core.

8. The condenser bushing according to claim 1 , wherein the condenser core is shaped in such a way that the thickness of an insulating material between the each of the edges of adjacent field-grading layers and the outer surface of the condenser core is greater than the thickness of an insulating material between the middle point between the edges of the field-grading layers and the outer surface of the condenser core.

9. An additive manufacturing method to manufacture the condenser bushing according to claim 1 .

10. An electrical insulation system comprising:
an active part comprising a conductor;
a condenser bushing disposed around the conductor, the condenser bushing comprising:
a condenser core and electrically conductive field-grading layers, which are embedded in insulating material of the condenser core and arranged around a central channel for a conductor extending along an axis defining an axial direction, an electric connection being provided to at least one of the field-grading layers,
pairs of neighbouring field-grading layers with the insulation material between them forming sections of the condenser core of axial lengths L 1 through L n and with capacitances C 1 through C n ,
a shape of at least one of the field-grading layers deviating from cylindricality to reduce non-uniformity of electric field stress of the condenser bushing compared to a corresponding condenser bushing with the cylindrical field-grading layers forming corresponding sections of the axial lengths L 1 through L n and with capacitances C 1 through C n , and
at least one of the field-grading layers being shaped such that the diameter of said field-grading layer varies along the axial direction, the diameter of said field grading layer having at least one maximum between the edges of the field-grading layer, wherein the maximums of the field-grading layers increase in amplitude along a radial direct

Assignees

• Hitachi Energy Ltd

Inventors

• Czyzewski Jan
• Banaszczyk Jedrzej
• Tremelling Darren
• Rybak Andrzej
• Kasza Krzysztof
• Matysiak Lukasz
• Perigo Elio

Classifications

• H01B17/28 Primary

  Capacitor type · CPC title

• H01G4/35

  Feed-through capacitors or anti-noise capacitors · CPC title

• H01G4/32

  Wound capacitors · CPC title

• H02G15/072

  of the condenser type · CPC title

• H01G4/40

  Structural combinations of fixed capacitors with other electric elements, the structure mainly consisting of a capacitor, e.g. RC combinations · CPC title