CN Tower Lightning Flash Characteristics Based on Current Records
In order to measure the lightning current, the exact location of the lightning strike must be known, which is possible at instrumented-tall towers, such as the CN Tower. Although, relatively recently, the CN Tower ceased to be the tallest manmade free-standing structure in the world, it is still the tallest tower that is fully instrumented for lightning measurements. The lightning current has been measured at the tower since 1991. Since 2011, the lightning current has been recorded by two independent measurement systems. Each measurement system has its own recording digitizer. One measurement system includes a 3-m 40-MHz Rogowski coil, a tri-axial cable and a two-channel 8-bit National Instrument (NI) PCI-5114 digitizer, featuring 64-MB memory with sampling rate of 250 MS/s. At 100-ns resolution, the PCI-5114 recording system has provided the continuous recording of the current for 750 milliseconds. The second measurement system consists of a 6-m 20-MHz Rogowski coil, a NanoFast optical system and a double-channel 8-bit LeCroy LT342L digitizer with sampling rate of 500 MS/s. At a sampling rate of 250MS/s, the LeCroy digitizer allows the recording of up to twenty 200-μs current signals for each flash. In 2015, a new $40,000.00 recording system (NI PXIe-5160) was acquired, featuring 2 seconds of continuous recording at 10-bit vertical resolution and 4-ns time resolution, providing – for the first time at the CN Tower – the recording of the current of the whole flash at substantially high resolutions. Since then, it has been possible, not only to record return strokes, with the best resolutions ever, but also impulses superimposed on the initial-stage current and the continuing current. This research proposal focuses on the statistical analysis of CN Tower lightning current flash characteristics (inter-flash time, flash time duration, flash components, initial-stage current duration, number of return-strokes, inter-stroke time, durations of continuing currents, return-stroke current peak, maximum rate-of-rise towards the current peak, etc.) based on available and future current records, especially those recorded by the newly acquired NI PXIe-5160 Data Acquisition System. The large size and quality of the lightning current data would permit the development of more sophisticated measures for lightning protection of tall structures, including wind turbines. In fact, lightning protection of wind turbines have recently become a priority.
The student taking this research internship position will participate in the operation and programming of the state-of-the-art lightning measurement systems. The duties include the active participation in the lightning current data acquisition during the 2017 lightning season (May-August), as well as the processing and analysis of acquired and future lightning current data for the eventual goal of deriving statistics concerning the characteristics of flash components. In addition to the applicant’s direct supervision, the student will interact with the applicant's graduate students (presently: 1 PhD’s and 3 MASc’s). The applicant schedules meetings with his research team, especially during the lightning season, in which everyone present a progress report concerning his/her achievements/difficulties. Thus, every member of the research team gains awareness of the work of others. Graduate and undergraduate research students are directed to submit their research accomplishments to relevant national/international conferences. It is worth mentioning that the applicant has fully supervised eleven NSERC USRA students since the summer of 1998. Also, two full-time URO students, and eight full-time and eleven part-time research assistant undergraduate students were fully supervised by the applicant since 2004. He also fully supervised four undergraduate summer research internship students during the last 4 years. Since 2002, the applicant’s fully-supervised "undergraduate" students presented 13 papers at the International Conference on Upcoming Engineers (ICUE) and the Cage Club Student Conferences on High Voltage Engineering and Electrostatics.
Completion of the fourth semester is important. Practical orientation and computer literacy are required. Previous research experience, especially in related fields, is a great asset.
Ali Hussein : CN Tower Lightning Flash Characteristics Based on Current Records | Sunday March 26th 2017 03:07 PM