High-voltage insulators in a 550 kV circuit breaker testing jig. The porcelain columns are five meters tall. Credit: Liebermann; Schulze KG, Germany.
We post plenty of stories about electrical power, but almost always from the perspective of R&D of technologies for renewable power generation. The transmission and distribution of the power is assumed. Even so-called smart grids will probably be based on transmission and distribution technology that has many common features to what is being used now. However, a new book, High-Voltage Insulators: Basics and Trends for Producers, Users and Students, by Johannes Liebermann, explains that the technology that goes into making porcelain high-voltage insulators is not so simple, and new demands for power are driving development of stronger, more durable insulators.
The high-tension transmission wires we see stringing from tower to tower are bare and carry a load of 110 kV or more. The air does a good job of insulating them, but they need to be insulated at the touch points, for example, at the tower pylon supports and where they enter buildings, etc. Traditionally, quartz-based porcelain insulators have been used, but they are susceptible to microcracking, according to the book.
“Although considered old, these materials are actually high-tech in terms of production, reliability, and durability,” says Alex Michaelis in the Foreword. Michaelis is director of the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden, Germany. The institute has partnered with Liebermann for many years on high-voltage insulator research, and the book draws from the fruits of that collaboration.
High-voltage ceramic porcelain insulators with high corundum content are much more reliable than the quartz-based ones. High-voltage insulators are subject to electrical stresses, mechanical stresses, thermal shock stresses and attack from environmental factors, such as pollution. Liebermann says in the book, “The most important goal is to achieve a maximum portion of α-corundum in the microstructure. By its high elastic Young’s modulus and high density corundum also causes a rise of Young’s modulus and density of the porcelain, therefore being the crucial factor for strength.”
A new book addresses the engineering of ceramic porcelain insulators for high-voltage applications. Credit: Schulze KG, Germany.
The book is organized into three chapters. Chapter 1, “Basics and trends,” covers the relationships between microstructure, properties and strength and aging. It also looks at how surface properties and insulator design impact electrical properties. The review excerpt I received of Chapter 1 includes many images of quartz-based and alumina-rich microstructures that are used to illustrate the superior service properties of the latter. There are also plenty of images of insulators and failed quartz-based porcelain insulators.
Chapter 2, “Demands, applications, design, market,” gets into the design considerations for specific applications such as insulators for overhead transmission lines, circuit breakers and supporting post insulators. The author includes a section on the current market and business trends for these components. Not surprisingly, growth areas are expected to be in Asia and South America.
The final chapter is “Manufacturing process and quality assurance.” In this chapter the author “would like to provide support in order to answer current questions and solve problems that may arise in manufacture and quality assurance.”
The book was translated into English by Arndt Spindler. For more information contact:
Druckerei und Verlag H. O. Schulze KG
Viktor-von-Scheffel-Straße 29
96215 Lichtenfels
Phone: +49 (0) 95 71 / 7 80-0
Internet: www.schulze-kg.de
Update, July 13:
The English translation of the book be ordered by contacting the author at johannes_liebermann@t-online.de or the editor, Stefan Zipfel, at stefan.zipfel@schulze-kg.de.
The cost is €100 (or foreign currency equivalent) plus shipping.