Alcoa Dumbbell Damper
Alcoa Fujikura, Ltd. manufactures a "bus damper" that is used for tubular busses in electrical substations. The damper had a multi-wire cable with two 6.9 lbs (3.1 kg) weights suspended from the each end of the cable. As the weights oscillate at the end of the cable, friction between the wires dissipates energy. The period of the dumbbell damper was measured to be approximately 0.8 sec.