Stockbridge damper

The Stockbridge vibration damper is a vibration absorber for reduction of mechanical vibrations of electrical lines, in particular high voltage power lines with long spans between poles.

This type of vibration was invented in 1928 by George H. Stockbridge, who at this time worked as an engineer at the company Southern California Edison.

Cause of the oscillations

A steady, albeit moderate wind can lead to standing waves with a few wavelengths at the head rope between two poles. This constitutes a major cause of the mechanical damage to the insulators

To reduce constructively matched damper elements are attached, especially in long-line fields, consisting of a short piece of rope with gauge blocks. These are clamped near the suspension points to the conductor cable. Stockbridge vibration damper have the shape of a dumbbell, which is centrally connected to the lead rope over a suspension.

Impact areas

Wind may at overhead lines lead to mechanical oscillations in the following frequency ranges:

• The so-called " galloping line " with the amplitudes of a few meters and a frequency in the range of 0.08 Hz to 3 Hz
• Vibrations due to the aero-elasticity, which has amplitude in the range of a few millimeters to a few centimeters and is in a frequency range of 3 Hz to 150 Hz.

Stockbridge vibration damper are particularly effective against vibrations due to the aeroelasticity at a level determined by the design frequency. By an asymmetric mass distribution of the damping elements good damping properties can be achieved in different frequency ranges.

Stockbridge vibration damper continue to be used for vibration damping on the guy ropes of transmission towers and cable-stayed bridges.