T&D World Magazine

Maciej Kumosa: Pioneering High-Voltage Research

Maciej Kumosa’s belief in ethics, integrity, practicality, innovation and creation has led him to be the pioneer in modern high-voltage research, as he practices all of those qualities in his personal and professional life. Kumosa has provided practical solutions to several major engineering problems--for example, NCIs and composite conductors. He will continue to solve engineering problems because it is in his nature. Kumosa is an international expert in advanced composites, nanotechnology, mechanics and damage of composites. T&D systems all over the world are full of composites, and he understands them well. “However, I fully appreciate their complexities, which humbles me when discussing composite-related issues,” Kumosa said.

Kumosa has been involved in or has led research since 1985, where he was a research faculty member in the Department of Materials Science and Metallurgy at Cambridge University in England. He had previously received his masters and PhD degrees in applied mechanics and materials science from the Technical University of Wroclaw in Poland. He is currently a John Evans Professor of Mechanical Engineering and the Director of the Center for Nanoscale Science and Engineering at the University of Denver. His research interests include numerical and experimental investigation of nano-, micro-, and macro-property degradation of advanced Polymer Matrix Compoites (PMS) used in electrical and aerospace applications when subjected to extreme environmental conditions.

Kumosa’s newest project is to build a national Industry/Cooperative Research Center (I/UCRC) for Novel High-Voltage/Temperature Materials and Structures. As part of the Center related efforts, the National Science Foundation has recently authorized Kumosa and his two partners from the Michigan Technological University (Professor Greg Odegard) and from the University of Illinois at Urbana-Champagne (Professors Iwona Jasiuk and Martin Ostoja Starzewski) to call a meeting of all U.S. industries interested in novel high-voltage/temperature materials and structures. The main idea behind the meeting is to jointly build the center, which will be jointly managed by the above universities, member industries and NSF.

The meeting will be held at the University of Denver on Dec. 3-4, 2012. So far the partners have received confirmations regarding the participation in the meeting from the Bonneville Power Administration, Tri-State, Western Area Power Administration, Electric Power Research Institute, MacLean Power Systems, National Institute of Standard and Technology, Lockheed Martin Corp., Third Millenium and Dow Chemical.

The three universities will work on several major research projects related to HV power transmission using next-generation materials and structures. An industry advisory board (IAB) will supervise the projects. An approximately $40k/year participation fee will be used to support the research performed for the member industries. Only 10% will go to overhead from the fees. Therefore, most of the funding from the industry will be used to support the researchers, not administration.

The NSF will be overseeing all research efforts in this truly fascinating center of excellence, making sure that the work is supervised by the IAB and is done for the benefit of the participating industries. If it is successful, the center will last about 10 years and should generate several millions of dollars per year, numerous inventions, improvements, publications, advanced graduate degrees and others, according to Kumosa. Kumosa competed for the grant, which was awarded this past summer.

His extensive experience with research puts him in an excellent position to advance technology and educate a new generation of graduate students. Interacting with his graduate students at DU is one of his favorite roles. He reminds students to “be honest, open-minded, positive, and always keep looking forward. Be practical and creative. Compete, but fairly.”

Kumosa has taught numerous undergraduate and graduate courses, including, Composites, Advanced Composites, Nanotechnology, Advanced Nanotechnology, Numerical Methods, Mechanics, Materials Science, and Advanced Materials Science.

He is an extremely active person and is always doing something. The results of his past and ongoing research projects shows. Kumosa has changed the power industry with his findings in high-voltage line insulators and high-voltage/high-temperature third-generation conductors.

To understand how Kumosa came to high-voltage work, you must start at the Oregon Graduate Institute in 1990. He was involved in the failure analysis and design of advanced metallic alloys for jet engine applications as part of the GE90 project. His first research group in the United States investigated the resistance to high-temperature fracture and fatigue of nickel-based superalloys and titanium aluminides used in the GE90 engine. At the same time, he started developing new research programs in the area of polymer matrix composites (PMC), which was more consistent with his research experience gained at Cambridge. Kumosa subsequently moved the PMC program to the University of Denver. His main research activities at DU since 1996 have been primarily related to the use of PMCs, either at elevated temperatures or in HV electric field applications. The programs were supported by three consortia of federal and private sponsors.

HV Transmission Line Research

Between 1993 and 2006, Kumosa supervised major interdisciplinary research efforts in the area of HV composite insulators.

Kumosa said that in-service, insulators are subjected to the combined action of extreme mechanical, electrical and environmental stresses. Due to the presence of these stresses, catastrophic failures of the insulators occurred quite frequently in-service in many regions of the world. Because of his composite background, the U.S. government (DoE) requested Kumosa's involvement in a major study in 1992 leading to the comprehensive evaluation of the suitability of polymers and their glass composites in HV transmission line applications.

The primary goal of the HV insulator research was to understand the fundamental mechanisms leading to the premature mechanical and electrical failures of the insulators in-service and to improve the design of the insulators. This research was extensively funded through multiple contracts by the Electric Power Research Institute and a consortium of electric utilities and insulator manufacturers consisting of the Bonneville Power Administration, the Alabama Power Co., the Western Area Power Administration, Pacific Gas & Electric, the National Rural Electric Cooperative Association and NGK-Japan. Thanks to the generous support of the sponsors, Kumosa's research groups, initially at OGI and then at DU, made truly major contributions to composite insulator technology.

Kumosa's most important accomplishments in this area include:

  • Explanation of 345 kV and 500 kV brittle fracture failures experienced by WAPA and PG&E
  • Identification of the type of acid responsible for brittle fracture
  • Simulation of brittle fracture with and without high voltage
  • Identification of several critical conditions leading to brittle fracture and other mechanical and electrical failures
  • Providing a ranking of the commonly used GRP rod materials for their resistance to brittle fracture and other failure modes (electrical, overcrimping, mishandling, etc.)
  • Recommendation of numerous experimental and numerical procedures critical for insulator design.

HV HT Third-Generation Conductor Research

Kumosa was also involved in research at DU for the numerical and experimental failure analysis of advanced high-temperature graphite/polyimide systems for aerospace applications. Then in 2008, he began investigating HT HV Polymer Core Composite Conductors (PCCC) for HV transmission line applications.

“Due to the rapidly increasing demand for electric power and the development of new sources of energy, there is an urgent need in this country and abroad to be able to transport more electric power, more efficiently, using the existing rights-of-way,” Kumosa said. “However, the current designs of HV conductors based on steel (for strength) and aluminum (for conduction) strands used in regional grids exhibit several limitations. Primarily, they are limited by their propensity to sag.”

Therefore, new conductors, with significantly better resistance to sagging, are being designed. One of them is the PCCC design. The PCCC conductors are based on a unidirectional polymer matrix composite core with carbon and glass fibers for strength and stiffness, and aluminum strands for conduction. They can transport up to three times more power than the current designs based on steel and aluminum. In addition, the PCCC sag significantly less than established overhead conductors. Since the conductors are designed with an expected life of 50 years, their structural deterioration with time needs to be well understood considering the in-service temperatures of up to 180°C, high concentrations of ozone, atomic oxygen, nitric acid and other pollutants, as well as, a variety of extreme dynamic mechanical and electrical loading conditions.

The HT HV conductor research at DU is being currently funded by the Western Area Power Administration, the Tri-State Generation and Transmission Association, Inc., and the Bonneville Power Administration. The National Science Foundation has very recently awarded a large three-year grant to Kumosa to support his industrial research on PCCCs. Major efforts are also underway to expand the current group of the sponsors to include the California Energy Commission, XcelEnergy, the Electric Power Research Institute and others.

The HT HV transmission conductor research has shown so far that:

  • The most damaging loading case for PCCC occurs if the conductors are subjected to large bending moments over mandrels with "relatively," small diameters. The most internally overstressed region of the rod under bending was found inside the carbon/epoxy section of the rod just near the carbon/glass fiber interface, on the compressive side of the rod.
  • Bending PCCC rods over small mandrels will generate compressive stresses in the rods high enough to cause fiber kinking and large delaminations affecting mechanical properties of the conductors in-service.
  • There is a clearly defined critical bend radius for the catastrophic failure of the current designs of the PCCC conductors. Using the critical bend radius determined numerically and verified experimentally, three catastrophic failures of the conductors which occurred in Poland in 2008 could be explained. Our explanations were reported to the transmission line community in 2010 (IEEE PES, Minnesota July 2010).
  • PCCC rods showed a strong sensitivity to transverse loading under aeolian vibrations. This indicates that the bearing stress due to crimping the conductor at a dead-end connection of a transmission line must be considered for effective fatigue life design.
  • Exposure to HT in ambient air seems to be much more damaging to PCCC rods than the effect of highly concentrated ozone.

Kumosa’s research has produced “useful and practical science,” which is another favorite aspect of his role at the University of Denver. As an extremely active person, he not only teaches, researches and mentors, he also gardens, studies astrophysics and cosmology, working around his beautiful mountain property in Cuchara, playing with his dogs, interacting with his “mountain friends” and playing piano.

For more information on the Denver meeting, you can contact Kumosa at [email protected].

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