Project Title:

Dielectrometry Sensors and Algorithms in Non-Destructive Testing of Materials, Electrical Power Apparatus, and Civil Infrastructures

Principal Investigators:

Markus Zahn

Research Staff:

Jason Sears

Sponsor:

Program Areas:

Continuum Electromechanics
High Voltage

Duration:

Abstract:

This program develops and applies dielectrometry technology to non-destructive testing of materials and systems. Interdigital frequency-wavelength dielectrometry can be used to measure stratified distributions of dielectric permittivity and conductivity of insulating materials. The complex dielectric permittivity is directly related to other material properties, such as moisture content, temperature, concentration of impurities and additives, density, aging status, etc. The analysis of spatial and temporal variations of these properties lends valuable insights into physical phenomena that take place in materials, electric power apparatus, and civil infrastructures; provides instrumentation for system monitoring and diagnostics; and can be used for optimization of design and performance characteristics.

Recent work has improved the performance of dielectrometry sensors through optimizations of geometrical design, materials, manufacturing processes, electronic circuitry, and computer algorithms. Accumulated effects of non-idealities of geometry, of the experimental setup, and the sensor are accounted for through empirical measurements, calibration, and use of finite-element calculations. Three distinct operating modes have been developed to optimize this technology: floating voltage with grounded back-plane, floating voltage with guarded back-plane, and short circuit current. Gain/phase measurements of dielectric permittivity and conductivity over the frequency range 0.005 - 10,000 Hz have good agreement with literature values of many liquid and solid dielectrics and composites; have been used to measure porosity in NASA supplied ceramics and in microporous alkaline battery separators; have monitored toxic vapor absorption (toluene) in chemical protective garments; have detected flaws in glass-fiber epoxy composites; have measured spatial profiles of moisture diffusion into oil-free and oil-impregnated transformer pressboard; have measured the Debye length, zeta potential, molecular diffusion coefficients, and positive and negative charge mobilities in interfacial electric double layers; and can be used in large size geometries to detect buried objects such as plastic and metallic land mines.

Continuing research is to define and solve non-destructive testing problems and to develop a practical technology. Specific work tasks include: (1) continuing to improve sensor design and parameter estimation algorithms for many measurement applications including the use of specialized substrate or coating materials for selective absorption of materials; (2) theoretical modeling and measurements incorporating the multi-wavelength interdigital dielectrometry sensor into a test apparatus that simulates a power transformer in order to investigate moisture absorption and desorption diffusion into and out of oil-impregnated transformer pressboard and related effects on flow electrification phenomena; (3) measurement and modeling of interfacial electrochemical double layers including control of reaction rates by imposing electric potentials to drive the double layers out of equilibrium; and (4) the use of dielectrometry to study corrosion, aging, sub-surface moisture, oxidation and cracking in civil infrastructures, such as concrete, wood, and painted metal structures.

References and Links:

Publications:

1. Sheiretov, Y. and M. Zahn, "Dielectrometry Measurements of Moisture Dynamics in Oil-Impregnated Pressboard," IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 2, No. 3, pp. 329-351, June, 1995.
2. Washabaugh, A.P. and M. Zahn, "A Study of Flow Electrification Using a Couette Flow Facility," IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 3, No. 2, pp. 161-181, April, 1996.
3. Mamishev, A.V., B.C. Lesieutre, and M. Zahn, "Optimization of Multi-Wavelength Interdigital Dielectrometry Instrumentation and Algorithms," IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 5, No. 3, pp. 408-420, June 1998.
4. Washabaugh, A.P. and M. Zahn, "A Chemical Reaction Based Boundary Condition for Flow Electrification," IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 4, No. 6, pp. 688-709, December, 1997.
5. Mamishev, A.V., Y. Du, B.C. Lesieutre, and M. Zahn, "Development and Applications of Fringing Electric Field Dielectrometry Sensors and Parameter Estimation Algorithms," accepted for publication in the Journal of Electrostatics, 1999.
6. Du, Y., M. Zahn, B.C. Lesieutre, A.V. Mamishev, and S.R. Lindgren, "A Review of Moisture Equilibrium in Transformer Paper-Oil Systems," IEEE Electrical Insulation Magazine, Vol. 15, No. 1, pp. 11-20, January-February 1999.
7. Sheiretov, Y. and M. Zahn, "Dielectrometry Measurements of Moisture Dynamics In Oil-Impregnated Pressboard", Conference Record of the 1994 IEEE International Symposium on Electrical Insulation, June 5-8, 1994, Pittsburgh, PA, pp. 33-36.
8. Washabaugh, A.P. and M. Zahn, "Flow Electrification Measurements In A Couette Flow Facility," Conference Record of the 1994 IEEE International Symposium on Electrical Insulation, June 5-8, 1994, Pittsburgh, PA, pp. 133-136.
9. Sheiretov, Y. and M. Zahn, "Dielectrometry Measurements of Spatial Moisture Profiles in Oil-Impregnated Pressboard," Proceedings of the 4th International Conference on Properties and Applications of Dielectric Materials, July 3-8, 1994, Brisbane, Australia, pp. 701-704.
10. Washabaugh, A.P., and M. Zahn, "Terminal Voltage and Current Measurements Due to Flow Electrification," Proceedings of the 4th International Conference on Properties and Applications of Dielectric Materials, July 3-8, 1994, Brisbane, Australia, pp. 825-875.
11. Mamishev, A.V., Y. Du, and M. Zahn, "Measurement of Dielectric Property Distributions Using Interdigital Dielectrometry Sensors," Conference on Electrical Insulation and Dielectric Phenomena, Oct. 22-25, 1995, Virginia Beach, Virginia, pp. 309-312.
12. Du, Y., M. Zahn, A.V. Mamishev, and D.E. Schlicker, "Moisture Dynamic Dielectrometry Measurements of Transformer Board Using A Three Wavelength Dielectrometry Sensor," 1996 IEEE International Symposium on Electrical Insulation, June 16-19, 1996, Montreal, Quebec, Canada, pp. 53-56.
13. Mamishev, A.V. and M. Zahn, "Techniques for Semi-Empirical Characterization of Material and Sensor Properties in Interdigital Dielectrometry," 1996 IEEE International Symposium on Electrical Insulation, June 16-19, 1996, Montreal, Quebec, Canada, pp. 486-489.
14. Schlicker, D. and M. Zahn, "Anomalous Oil Electrification Phenomena in Couette Flow Between Bare Stainless Steel Electrodes," 1996 IEEE International Symposium on Electrical Insulation, June 16-19, 1996, Montreal, Quebec, Canada, pp. 741-744.
15. Washabaugh, A.P. A. Mamishev, Y. Du and M. Zahn, "Dielectric Measurements of Semi-Insulating Liquids and Solids," 12th International Conference on Conduction and Breakdown in Dielectric Liquids, July 15-19, 1996, Rome, Italy, pp. 381-384.
16. Du, Y. and M. Zahn, "Dielectrometry Measurements of Effects of Anti-Static Additives on Transformer Board" (abstract only), 1996 Annual Report for the Conference on Electrical Insulation and Dielectric Phenomena, p.194.
17. Schlicker, D. and M. Zahn, "Effects of Transformer Aged Oil on Electrification In a Couette Flow" (abstract only), 1996 Annual Report for the Conference on Electrical Insulation and Dielectric Phenomena, p.327.
18. Mamishev, A.V., M. Zahn, B.C. Lesieutre, and B.A. Berdnikov, "Influence of Geometric Parameters on Characteristics of an Interdigital Dielectrometry Sensor," 1996 Annual Report for the Conference on Electrical Insulation and Dielectric Phenomena, pp. 550-553.
19. Mamishev, A.V., B.A. Berdnikov, J.P. Rivenc, B.C. Lesieutre, and M. Zahn, "Surface Contact Effects on Interdigital Dielectrometry," submitted to the 10th International Symposium on High Voltage Engineering, Aug. 25-29, 1997, Montreal, Canada, Vol. 6, pp. 357-360.
20. Du, Y., M. Zahn, and B.C. Lesieutre, "Dielectrometry Measurements of Effects of Moisture and Anti-Static Additive on Transformer Board", 1997 Annual Report of the Conference on Electrical Insulation and Dielectric Phenomena, Minneapolis, MN, Oct. 19-22, 1997, pp. 226-229.
21. Mamishev, A.V., B.C. Lesieutre, and M. Zahn, "Parameter Estimation Using an Interdigital Dielectrometry Sensor with Finite Element Software", 1997 Annual Report of the Conference on Electrical Insulation and Dielectric Phenomena, Minneapolis, MN, Oct. 19-22, 1997, pp. 234-237.
22. Mamishev, A.V., Y. Du, B.C. Lesieutre, and M. Zahn, "Measurement of Stratified Distributions of Dielectric Properties and Dependent Physical Variables", 1997 Fall Meeting of the Materials Research Society, Dec. 1-5, 1997, Boston, MA, paper no. EE 4-11.
23. Mamishev, A.V., C. Lin, Y. Du, B.C. Lesieutre, and M. Zahn, "Improvements of Algorithms for On-Line Interdigital Dielectrometry Measurement of Material Properties," IEEE International Symposium on Electrical Insulation, pp. 444-447, June, 1998. 
24. Mamishev, A.V., Y. Du, B.C. Lesieutre, and M. Zahn, "Development and Application of Multi-Wavelength Interdigital Dielectrometry Sensors and Parameter Estimation Algorithms," Electrostatics Society of America-Institute of Electrostatics Japan Joint Symposium on Electrostatics, San Francisco, CA, June 23-26, 1998, pp. 169-181.
25. Mamishev, A.V., Y. Du, B.C. Lesieutre, and M. Zahn, "Measurement of Moisture Spatial Profiles in Transformer Pressboard," 1998 IEEE Conference on Electrical Insulation and Dielectric Phenomena, Atlanta, GA, October 25-28, 1998, pp. 323-326.
26. Du, Y., A.V. Mamishev, B.C. Lesieutre, and M. Zahn, "Measurement of Moisture Diffusion as a Function of Temperature and Moisture Concentration in Transformer Pressboard," 1998 IEEE Conference on Electrical Insulation and Dielectric Phenomena, Atlanta, GA, October 25-28, 1998, pp. 341-344.
27. Sheiretov, Y., "Dielectrometry Measurements of Moisture Dynamics in Oil-Impregnated Pressboard," MIT MS thesis, May, 1994.
28. Schlicker, D.E., "Flow Electrification in Aged Transformer Oils," MIT MS thesis, September 1996.
29. Mamishev, A.V., "Sensor design and Property Estimation Algorithms Based on Interdigital Dielectrometry," MIT Ph.D. thesis, May, 1999.
30. Du, Y., "Measurements and Modeling of Moisture Diffusion Processes in Transformer Insulation Using Interdigital Dielectrometry Sensors," MIT Ph.D. thesis, May, 1999.

This web page is maintained by Brett Klein. Email questions/comments to him at bklein@mit.edu.