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Standards for Insulating links
ANSI/CPLSO-14
ANSI/UL2737 (Withdrawn)
ASTM F2973
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Tests by Independent Organizations
Load Insulator
Miller & Hirtzer
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G. G. Karady et d: Performance Evaluation of Insulating Links Used for Worker Protection in Cranes 7 CONCLUSION The paper presents the results of laboratory experiments evaluating the protection provided by insulating links. The major fmdings are: The short duration energization of polluted and wet- ted insulating link produced transient leakage current, discharge phenomena and ultimately flashover. These processes are significantly different from the process that was observed on transmission line insulators The previous research concentrated on the probabil- ity of insulating link flashover. This paper shows that the transient and rms leakage current must be used to assess the protection provided by an insulating link. The leakage current of polluted and wetted links de- pends on the time of energization. The maximum lea- kage current was determined by statistical analysis. Both Insulating Links A and B provided perfect pro- tection up to the rated voltage in heavily polluted and & condition. The transient capacitive leakage peak current was less than 2.66 mA and its duration was less than half a cycle. Heavily polluted, wet Insulating Link A provides perfect protection up to less than - 21 kV line-to-line voltages. The level of adequate protection is less than - 38 kV line-to line voltages. Heavily polluted, wet Insulating Link B provides per- fect protection up to - 25 kV line-to-line voltages. ..The level of adequate protection is less than 52 kV line-to line voltage. Lightly polluted, wet Insulating Link A provides per- fect protection up to - 42 kV line-to-line voltages. The level of adequate protection is less than 69 kV line-to line voltage. The test results were generalized by calculating the average electric stress that provides perfect or ade- quate protection. Based on the findings it can be concluded that use of either of the tested Insulating Links would reduce significantly the number of accidents caused by crane-transmission line con- tact. It is not expected that the links will eliminate all acci- dents, but would definitely save several lives each year. The authors gratefully acknowledge the contributions of Glenda Cochran for the partial sponsorship of the tests and M. Pratt for the measured natural pollution data in England. 9 REFERENCES [I] Doyle R Peeks: "Crane accident statistics," available at http://www.craneaccidents.comlsta&.htm [2] Insulatus Inc. "Load insulators and tag line insulator overhead power line protection for crane safety," available at: http:Nwww.insulatus.com/theproblemhtm [3] H. J. Hirtzer & Assoc., Inc, "Insulating Links," available at: http:/hjhirtzer.com [4] G. G. Karady, ''Efficiency of insulating links for protection of crane workers", IEEE Trans. Power Delivery, Vol. 6, pp. 3 16-323, 1991. [5] J. D. Morgan and H. B. Hamilton, "Evaluation of link for safety applica- tions", Report, R.O. Corporation and National Crane Company, 1982. [6] J. D. Morgan, "Evaluation of insulating links for cranes", unpublished test data prepared for Grove Manufacturing Inc. 1985, (Not reviewed). [7] J. D. Morgan, "Insulating link and standoff evaluation for grove ganu- facturing Inc.", A.B. Chance Test Laboratories, Centralia, Missouri, 1990. [8] Ontario Hydro Report No. ET91-94-P, "Electrical tests on insulating crane links", Aug. 13, 199 1. [9] J. D. Morgan, "Insulating link test using IEC 507 artificial pollution methods", A.B. Chance Company, Centralia, Missouri, 1992. [lo] G. G. Karady, M. Shah, and D. Dumora, "Probabilistic method to assess insulating link performance for protection of crane workers", IEEE Trans. Power Delivery, Vol. I I, pp. 212 -323, 1996. [I I] CEVIEC Standard 60507-199 1, "Artificial pollution test on high voltage insulators to be used on a.c. systems," 2nd edition, 1991-04. [12] IEEE Std 4-1995, "Standard Techniques for High-Voltage Testing" [I31 D. C. Montgomery, Design and ana[ysis of experiments, 6th edition, New York, John Wiley and Sons, 2004. [I41 IEC Standard 479-1, "Effect of current on human beings and livestock". George G Karady (SM'70-F'78) He received the BSEE and Doctor of Engineering degrees in electrical engineering from Technical University of Budapest. Dr. Karady is Salt River Project Chair Professor at Arizona State University, where he teaches electrical power and performs research in power electronics, high voltage techniques and electric power systems. Previously, he was with EBASCO Services where he served as Chief Consulting Electrical Engineer, Man- ager of Electrical Systems and Chief Engineer of Computer Technology. Before that he was ~lectrical Task supervisor for the Tokomak Fusion Test reactor project at Princeton. Before that he worked for the Hydro Quebec Institute of Research as a Program Manager. Dr Karady started his career at Technology University of Budapest where he progressed from Post Doctoral Student to Deputy Department Head: Dr. Karady is a registered professional engineer in New York, New Jersey and Quebec. He is the author of more than 200 technical papers. Dr. Karady is active in IEEE; he was chair of Chapted Membership's Award Committee, Education commit- tee's Award Subcommittee and WG on Non-ceramic insulators etc. Dr. Karady also served in the US National Connnittee of CIGRE as Vice Presi- dent and Secretary Treasurer. Essam Al-Ammar (901) was born in Riyadh, Saudi Arabia. He received his BS degree (honor) in electrical engineering from King Saud University in 1997. From 1997-1999, he worked as a Power/software engineer at Lucent Technologies in Riyadh. He worked as an In- structor at King Saud University between 1999-2000. In 2003, he received the MS degree from the Univer- sity of Alabama, Tuscaloosa, AL. He is currently a Ph.D. student at Arizona State University. His current research and academic interests include dry-band arc- ing on fiber-optic cables, high voltage engineering, power system transmis- sion, distribution and protection. S. Venkataraman (S704), was born in Chennai, India in 1977. He received the BE degree from Bharathi- dasan University, India in 1998. He worked with MIS Lucas TVS Company in Chennai as a development engineer for 3 years. He finished MS on prediction of degradation of polymer material (thesis) in electrical engineering at ASU in 2003. He is currently pursuing a Ph.D. degree and working on prediction of flashover voltage of insulators. His interest is on the use of polymeric materials for outdoor application.
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