Experimental Simulation of Wet-Snow Shedding from Sagged Cables

The process of wet-snow shedding from overhead cables was simulated in cold-chamber experiments under different ambient conditions. The main objective of the study was to examine how cable sag influences the snow-shedding process. However, the effects of several other parameters were also considered, such as air temperature, solar radiation, snow-sleeve length, and periodic excitation of the cable. Periodic excitation was applied at the suspension point of the cable, leading to cable vibration which may simulate galloping. The two most important parameters related to wet snow adhesion to the cable, liquid water content and density, were measured as a time function along the entire snow sleeve until snow shedding occurred. The experimental observations were compared to data gathered in a recent study on snow shedding from cables with negligible sag. The main difference between negligible and large sag is that with the latter water migrates to the lower region of the sleeve in the middle of cable, and that droplets start dripping after the snow becomes locally saturated. The time when dripping began and the mass of dripping water were also measured. Forced cable vibration accelerated the shedding process; the relationship between the excitation amplitude and the time when shedding occurred were determined. Experiments also revealed that the maximum liquid water content of snow, which was reached when shedding occurred, depended on the initial snow density.