Research Consulting Associates has conducted scores of the research and development projects for private industry and agencies of the Federal Government, including NSF, DOE and NASA. Research includes examining methods for effectively controlling high-frequency vibration and low frequency galloping of power lines. Field studies include measuring product performance and the analysis of data on galloping.
Studying the Probability of Galloping. In 1998, Research Consulting Associates pioneered one of the most comprehensive studies on galloping based on field data collected over 3 years. Funded by Department of Energy, the study analyzed data collected by Ontario Hydro on the field performance of two anti-galloping dampers. Several hundred units of each damper were installed on the utility’s single circuit line for observation. One conclusion of this study was that the probability of galloping is a linear function. The other lesson learned in both this study and experience is that galloping is a phenomenon that cannot be controlled in a single span approach. Observed galloping in one span may have started in an adjacent one, and it may then relay the motion in both directions ahead and back. Treating one span where galloping has been observed does guarantee that the line will not gallop again nor will it protect adjacent spans from galloping. See A Study of Galloping Conductors on 230kV Transmission Line
Twister. PacifiCorp analyzed the Worland to Thermopolis line in Wyoming to determine the probability of conductor clashing. Field testing was initiated to compare effective galloping control by the AR Spacer Twister (polymer interphase with articulating clamps) and the AR Twister MOD3 (20lbs aluminum weight). These tests revealed that both devices eliminated galloping flashover. See PacifiCorp gets a Grip on Galloping Conductors, T&D World/April 2002.
Spacer Damper. A series of field tests were undertaken during December 1985 in Littleton, New Hampshire for the New England Power Company to measure the Aeolian vibration of a new triple bundle DC transmission line. The objective was to evaluate the performance of the damping devices installed on the Phase I transmission line. These tests provided design data for specifying vibration control devices for the Phase II line. Conclusions of the study included:
· vibration of a single conductor is 4-5 times less than the vibration of the triple bundle having five spacer-dampers of a particular type, and
· the level of vibration of the bundle having only one spacer-damper at mid-span and one end-point damper per sub-conductor is the same as a single conductor. See Vibration of Bundled and Single Conductors: A Comparative Case Study