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High-Voltage Insulators and Components

Lawrence Livermore National Laboratory

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Technology Marketing Summary

One of the ongoing challenges to improving performance in capacitors and other high-voltage electrical structures is to identify and reduce the factors that cause failure.  High-voltage devices typically fail following excessive partial discharge activity, which is a localized dielectric breakdown that does not transcend the main electrode gap spacing. One type of failure is anticipated to start at a triple junction, the point at which an electrode and two different dielectric materials intersect.

This invention seeks to reduce failures related to high-voltage structures, particularly to capacitors, bushings, connectors, and cables. It also offers manufacturing solutions that reduce electrical field stress in the identified weak areas.  In so doing, it also offers a very compact high-voltage switch with robust reliability.

Description

Innovative research at Lawrence Livermore National Laboratory (LLNL) has developed a specific set of technologies to address several areas of high-performance electrical component concern: 1) multi-layer film capacitors that must operate with a high degree of reliability; 2) feed-through bushings and coaxial connectors; and 3) methods for manufacturing these high-performance components, by which electrical field stresses are eliminated or sufficiently reduced in the weak areas.

The innovations include metalizing the surfaces of solid dielectric materials where contact is made with metal electrodes. Electric fields are thereby eliminated in the void regions, preventing the electrical discharge (corona) activity that degrades bulk dialectic materials and reduces performance. The result is similar to conventional solid-dialectic designs, in which fields across gaps are removed by metalizing a dielectric surface. In the novel LLNL application, significant improvements to the high-performance bushings, connectors, and film-capacitors add robust protection to existing systems.

Benefits
  • The LLNL improvements provide an approach to improving the performance of high-voltage capacitors in critical systems, as well as other highly stressed components and structures.
  • The manufacturing solution proposed by LLNL reduces inefficiencies and lowers the failure rate of all affected components, thereby improving margins and deliveries.
  • This metallization system improves the corona inception level (voltage/CIV), thus   strengthening weak dielectric areas.
  • Critical issues limiting the compactness of high-voltage systems are addressed by optimizing the design of a highly reliable solid-dielectric over-voltage switch.
  • The technique improves on conventional manufacturing methods by eliminating all anomalies at the dielectric-electrode interface of high-voltage structures.
Applications and Industries
  • Electrical component manufacturers can greatly reduce the profound difference between measured and calculated capacitance values for multi-layer film capacitors, delivering a more reliable product and lowering the percentage of failed product.
  • The technique can be applied universally in appropriate component manufacture to eliminate all anomalies at dielectric-electrode interfaces.
More Information

Compact High-Voltage Structures, llth IEEE International Pulse Power Conference,Baltimore, MD, June 29-July 2, 1997 (available through IEEE or OSTI)


Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Date
Patent 6,340,497
Patent
6,340,497
Method for improving performance of highly stressed electrical insulating structures
Removing the electrical field from the internal volume of high-voltage structures; e.g., bushings, connectors, capacitors, and cables. The electrical field is removed from inherently weak regions of the interconnect, such as between the center conductor and the solid dielectric, and places it in the primary insulation. This is accomplished by providing a conductive surface on the inside surface of the principal solid dielectric insulator surrounding the center conductor and connects the center conductor to this conductive surface. The advantage of removing the electric fields from the weaker dielectric region to a stronger area improves reliability, increases component life and operating levels, reduces noise and losses, and allows for a smaller compact design. This electric field control approach is currently possible on many existing products at a modest cost. Several techniques are available to provide the level of electric field control needed. Choosing the optimum technique depends on material, size, and surface accessibility. The simplest deposition method uses a standard electroless plating technique, but other metalization techniques include vapor and energetic deposition, plasma spraying, conductive painting, and other controlled coating methods.
Lawrence Livermore National Laboratory 01/22/2002
Issued
Patent 6,783,401
Patent
6,783,401
Apparatus for improving performance of electrical insulating structures
Removing the electrical field from the internal volume of high-voltage structures; e.g., bushings, connectors, capacitors, and cables. The electrical field is removed from inherently weak regions of the interconnect, such as between the center conductor and the solid dielectric, and places it in the primary insulation. This is accomplished by providing a conductive surface on the inside surface of the principal solid dielectric insulator surrounding the center conductor and connects the center conductor to this conductive surface. The advantage of removing the electric fields from the weaker dielectric region to a stronger area improves reliability, increases component life and operating levels, reduces noise and losses, and allows for a smaller compact design. This electric field control approach is currently possible on many existing products at a modest cost. Several techniques are available to provide the level of electric field control needed. Choosing the optimum technique depends on material, size, and surface accessibility. The simplest deposition method uses a standard electroless plating technique, but other metalization techniques include vapor and energetic deposition, plasma spraying, conductive painting, and other controlled coating methods.
Lawrence Livermore National Laboratory 08/31/2004
Issued
Patent 6,339,195
Patent
6,339,195
Apparatus for improving performance of electrical insulating structures
Removing the electrical field from the internal volume of high-voltage structures; e.g., bushings, connectors, capacitors, and cables. The electrical field is removed from inherently weak regions of the interconnect, such as between the center conductor and the solid dielectric, and places it in the primary insulation. This is accomplished by providing a conductive surface on the inside surface of the principal solid dielectric insulator surrounding the center conductor and connects the center conductor to this conductive surface. The advantage of removing the electric fields from the weaker dielectric region to a stronger area improves reliability, increases component life and operating levels, reduces noise and losses, and allows for a smaller compact design. This electric field control approach is currently possible on many existing products at a modest cost. Several techniques are available to provide the level of electric field control needed. Choosing the optimum technique depends on material, size, and surface accessibility. The simplest deposition method uses a standard electroless plating technique, but other metalization techniques include vapor and energetic deposition, plasma spraying, conductive painting, and other controlled coating methods.
Lawrence Livermore National Laboratory 01/15/2002
Issued
Technology Status
Development StageAvailabilityPublishedLast Updated
PrototypeAvailable02/06/201202/06/2012

Contact LLNL About This Technology

To: Charity Follett<follett2@llnl.gov>