Mechanical dampers for the contiol of full span galloping oscillations

The paper reviews previous work on aerodynamic and mechanical devices for the control of galloping oscillations. By considering energy input and energy dissipation, a value is set for the damping that mechanical devices need to give. The paper describes two ideas for mechanical dampers. The first is a cross-arm-mounted device driven by the swinging of the suspension insulators. Such dampers give large damping levels to the `one-loop¿¿ modes of galloping, and are unaffected by errors in damping rate or by ice accretion on the conductors. The second device is an inspan damper mounted on the conductors. This concept is not new, but an optimised and more effective damper can be produced. Results are presented for dampers optimised in each of two ways. It is shown that dampers having a small fraction of the mass of the conductor span should give significant improvement in galloping behaviour. The paper considers the problems of converting these two ideas into operational hardware.