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| Motion Control: Stockbridge-type Vibration Damper - 1700 Series |
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The HiTemp™ ACA Stockbridge Damper is the most efficient way to extend the life of a transmission line. It is designed to dissipate the damage caused by aeolian vibration.
What is Aeolian Vibration?
Aeolian vibration is a high frequency motion that can occur when a smooth, steady crosswind blows on aerial cables. This laminar wind creates vortices, which are detached at regular intervals on the leeward side, alternating from top and bottom of the cable. The detachments create vertical forces causing the cable to vibrate standing waves generally in high harmonic modes. The primary factors effecting aeolian vibration are span length, tension and impedence. The amount of energy imparted to a cable varies directly with the span length. With increasing tension, the tendency of a cable to vibrate rises rapidly as its self dampening ability reduces. Impedence is determined by the mechanical and material properties of the cable.
The first aeolian vibration fatigue failures of stranded conductor were reported in 1917. George Stockbridge of Southern California Edison first developed dampers in 1928. During this same timeframe, ACA erected an outdoor test span and indoor laboratory for the study of vibration. These expanded facilities, along with more than 70 years of research and experience, have assisted ACA in understanding the theory of vibration and its control. Aeolian vibration still occurs and causes damage to conductors, hardware and towers. ACA Stockbridge Dampers dissipates this damaging force of nature.
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Features:
Wide Vibration and Voltage Coverage
The ACA Stockbridge Damper has two natural frequency modes. These modes are commonly know as ‘flying’ and ‘wiggling’. ACA uses a specially designed 19 strand messenger wire allowing the damper to dissipate vibration, or ‘wake up’, at lower energy inputs. These two modes combined with the 19 strand messenger wire give ACA ’s Stockbridge Damper the widest range of vibration coverage in the industry. Damper assemblies with catalog weights of 1706 and larger can be used at 345kV and above.
Pressed Clamp and Weights
ACA Stockbridge Damper clamp and weights are pressed on to the messenger wire, as opposed to being cast or welded. The pressing operation does not alter the physical or mechanical characteristics of the messenger wire. Casting or welding anneals the messenger, compromising its performance.
No Special Tools Needed with Breakway Bolt Option
With the breakaway bolt, no special tools or torque wrench is needed. Simply tighten the bolt until the head shears off. This means proper torque has been achieved.
Proven Performance Year After Year
Comparative testing was conducted in 1993 at a private test site using ACA Stockbridge Dampers and those of two competitors. In this particular test, ACA dampers offered 40+ years of protection against fatigue, while the competitions’ dampers failed between 7 and 14 years.
Vibrec™ Damper Recommendation Program
The Vibrec damper recommendation program assists in damper requirements for transmission and distribution lines.
For more information contact the ACA Technical Support Team at 1.800.866.7385. |
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