Cable Vibration Dampers vibrastion analysis

1. Cable
Vibration Dampers
Chandrashekarachari.M
ENG16ME0015

2. Contents:
i. Introduction
ii. EffectOfVibration
iii. Types OfDampers
iv. Cable Vibrations
v. Damping Of Stay Cables
vi. The Effectiveness Of Vibration Damper Attached To The Cable

3. INTRODUCTION:
Cable dampers absorb cable vibrations induced by
traffic, rain and/or wind on anchored supporting
structures.
i. Very short reaction pathway due to low compressibility
ii. High efficiency at very low connection height to the structure to meet
architectural requirements
iii. Available also in semi-active design to ensure best possible efficiency

4. Due to wind, overhead transmission lines will be excited to vibrations and
oscillations that can lead to damage on the conductor of the overhead
transmission line, single parts or the pole. In order to reduce these
vibrations and oscillations to an uncritical dimension, damping systems
will have to be installed in the overhead transmission lines Wind-induced
vibration of overhead conductors is common worldwide and can cause
conductor fatigue Near a hardware attachment

5. EFFECT OF VIBRATION:
It should be understood that the existence of vibration on a
transmission or distribution line doesn’t necessarily constitute a
problem. however, if the magnitude of the vibration is high,
damage in the form of abrasion or fatigue failures will generally
occur over a period of time

6. TYPES OF CABLEDAMPERS
i. Stockbridge Damper
ii. ELGRA dampers
iii. Tersional dampers
iv. Haro damper
v. Twin Spacer Damper
vi. Triple spacer Damper
vii. Quadruple Spacer Damper

7. STOCKBRIDGE DAMPER
These dampers are used to counteract vibrations
excited by wind, Depending on the type of the the
conductor of the Overhead transmission line, several
damper types with many Different models are available.
The name of the damper is due to the scientist H.
Stockbridge, who advanced the development of the
damper in the 1920’s. The functional mode has not
changed up to now and is one of the methods

8. ELGRA DAMPERS
ELGRA dampers from Sweden were installed on the first
330kV lines emanating from the Snowy River. These consisted of
a number of weights resting on elastomer pads around a central
rod suspended vertically.

9. TORSIONAL DAMPERS
Torsional Damper is the most modern anti-galloping device
available today which has been specially designed for use
on bundled high voltage and extra high voltage (132kv and
up to more) power transmission lines.

10. HARO DAMPER
The Haro damper, although expensive, virtually solved the vibration
problems at Saskatchewan Power. Its one disadvantage was that it was
over a meter in length was difficult to transport and install.

11. SPACER DAMPERS
Spacers serve to establish a distance between the partial conductors of a
bundle line in order to prevent the conductors from knocking together and
thus avoid damage done to conductors. Spacer dampers will be used if
vibrations excited by wind need to be expected. the vibration amplitudes of
the conductor can be reduced to an uncritical dimension. In this context,
many different models of the spacers are available for different bundle
arrangements.

12. TWIN SPACER
Twin Spacer - Dampers are used to control vibration and
conductor oscillation, maintain conductor spacing and restore
conductor spacing after a short circuit occurs.

13. TRIPLE SPACER DAMPER
Spacer dampers were originally developed to suppress bundle conductor
sub span oscillations that could cause damage to multi-conductor
bundle systems.
Spacer Dampers are designed to provide corona free performance on
operating voltages up and including 500 kV. Special designs are available
for 765 kV applications.

14. QUADRUPLE SPACER DAMPER
Spacer-damper installed on a square four conductor
bundle to control both vibration and wake induced
oscillation.

15. Cable vibrations
i. Statics of stay cables
ii. Dynamics of stay cables
iii. Internal and aerodynamic damping
iv. Different types of cable vibrations
v. Countermeasures.

16. f 
mgL²
8F

17. k F
Tk

2L m

18. Damping of stay cables
Internal damping (ratio to critical) Injection with cement
grout : 0.01 % Lock-coil cable : 0.1 %
Parallel individually protected strands : 0.1 to 0.15%
Parallel strands injected with oil wax : 0.15 %
Aerodynamic damping
vertical vibrations
d k
k
d k
k
UDC T
UDC T
transverse vibrations 
 8m
4m



19. Cable damping depends on:
1. Material
2. Diameter
3. Length
4. Number of strands
5. Number of turns per length
6. Initial tension or preload
7. Displacement amplitude

20. The damping can be very nonlinear, particularly depending on
displacement amplitude.
The flexing of wire rope involves both coulombic and viscous
damping. At very low vibration levels, the wire strands stick
together and little sliding occurs. The damping is low and the
behavior is viscous.
With higher displacements, coulomb damping predominates as the
wires break free and start to slide against each other, absorbing
large amounts of energy.

21. The effectiveness of vibration damper attached to the cable
• Cables in structures play an important supporting function.
• They are part of the construction of suspension bridges and the power transmission lines.
• From the point of view of the structural analysis, cables are important element in the design process to
keep the sufficient ultimate and serviceability limit states.
• These constructions have large spans and low rigidity susceptible to deformation what was discussed .
• Because of low amplitudes often less than the diameter of the cable, these vibrations are slightly
perceptible, but may lead to material fatigue and then to failure.

22. The Displacement Depending OnThe Frequency OfVibration Of Cable With Damper AndWithout Damper.
The dependence of the displacement
versus frequency,
curve 1 - vibrations of the cable without
damper
curve 2 – Cable vibration for optimal
parameters of the damper
curve 3 – cable vibration for parameters
of the damper

23. END OF PRESENTATION
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