plp --- dogbone vibration damper
TRANSCRIPT
General RecommendationsDamping devices are designed for the single purpose of reducing or minimising
vibration, which damages conductors – whether current-carrying, earthing or staying
– at the point of suspension or attachment, especially if conductors are suspended in
suspension arrangements that apply radial stresses in a concentrated form. After
many years of research and experience, we have developed a damper efficient enough
to enable us to extend our range of vibration dampers beyond the achievements to
date.
®The DOGBONE vibration damper is an advanced and completely new form of the
accepted “STOCKBRIDGE” or “MONROE & TEMPLIN” dampers. It has a damping
efficiency as high as 70% in the 12-40 Hz range as compared to a 40% efficiency in the
range 11-13 Hz accepted for the traditional damper. In addition to the two ranges
covered and by virtue of the weight design and positioning on the messenger, we are
able to increase the energy absorption of the damper by applying a torsional stress to
the messenger.
® Dogbone Vibration Damper
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Copyright 2010 Preformed Line Products • All rights reservedTelephone: 033 397 5800 • Facsimile: 033 387 7094
Email: [email protected] Website: www.preformedsa.co.za
Features of the DOGBONE Damper:
Application:
Material:
® The damper is secured to the conductor
by the well-known and successful Preformed retaining rods. This securing method has
several advantages:
1. No concentrated radial stresses are set up under the clamp.
2. The complete elimination of dampers “wandering” up or down the line and causing
conductor damage.
3. Installation or removal may be carried out, without shut-down of the line, by hot-
stick application.
The design completely eliminates any moisture build up and is therefore again
superior to the conventional damper as far as corrosion is concerned.
The neoprene pad between damper and conductor offers the conductor protection
from abrasion from the damper clamp at the attachment point.
®And last but not least, no tools are required for the installation of the DOGBONE
damper.
Although it is possible, through laboratory and field studies, to evaluate
the capability of dampers (of any design) and to compare the efficiency of one against
another, the science is not such that a standard yardstick can be developed to indicate
the number of dampers which should be used on a line or span.
Since there are many variable characteristics involved in a particular line, the vibration
phenomenon is influenced by these characteristics. A theoretical evaluation to
determine the number of dampers can be done, but only for individual installations. In ®the case of the DOGBONE , tests have shown that it is more efficient than the
Stockbridge type dampers.
It is therefore standard practice to evaluate the number of dampers for a given line
design in each case.
The attachment clamp is a high grade aluminium alloy.
The messenger is 19 strands of high carbon steel.
The weights are of high grade Zinc. BS 1004A. The retaining rods are made from our TMusual high grade aluminium alloy used on all PREFORMED fittings.
® Dogbone Vibration Damper
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Copyright 2010 Preformed Line Products • All rights reservedTelephone: 033 397 5800 • Facsimile: 033 387 7094Email: [email protected] Website: www.preformedsa.co.za
® Dogbone Damper
DVD 543/606 2 kg each 13,8 - 15,0 4,7 kg
DVD 7110 2 kg each 18 - 27 4,7 kg
DVD 1114 3 kg each 28,5 - 36 6,8 kg
DVD7110/714 Wolf 30/7/2,59 1,5 m
DVD 740/787 Elm 19/3,76
Lynx 30/7/2,79 1,5 m
Poplar 37/2,87
DVD 826/925 Panther 30/7/3,0 1,6 m
Sycamore 37/3,23 1,8 m
Bear 30/7/3,35 1,7 m
DVD 7110G Goat 30/7/3,71 2,0 m
DVD 7110B2 Bison 54/7/3,0 2,0 m
DVD 1114Z Zebra 54/7/3,18 2,1 m
DVD 1114 Dinosaur 54/3,89 & 19/2,36 2,5 m
CATALOGUE WEIGHTS CONDUCTOR UNIT APPROX.
NO. USED DIA. mm MASS INCL.
RODS
®Positioning of Dogbone Dampers – Guide Chart Based on EPRI
Recommendation:
CATALOGUE CONDUCTOR DIMENSION FROM NO. SUSP CLAMP CENTRE
TO CENTRE OF DAMPER CLAMP
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Copyright 2010 Preformed Line Products • All rights reservedTelephone: 033 397 5800 • Facsimile: 033 387 7094
Email: [email protected] Website: www.preformedsa.co.za
PLP method to determine asymmetrical placement:
W = LOOP LENGTH AT CRITICAL FREQUENCY, M
ie. Frequency giving rise to shortest loop length.
½THUS S1,FIRSTDAMPER = 0,7xW = 0.282 x Dx (T) , M
(m)
1/2S2, SECOND DAMPER = 0,6 x W = 0.242 x D x (T) , M
(m)
1/2S3, THIRD DAMPER = 0,9 x W = 0.363 x D x (T) , M
(m)
CRITICAL FREQUENCY, Fc185 x WIND SPEED, V MIS,
HzCONDUCTOR DIAMETER, Dmm
=
CALCULATION BASED ON EMPIRICAL “STROUHAL” RELATIONSHIP
LOOP LENGTH, W ½(CONDUCTOR TENSION, T Kn) 310
M (MASS PER UNIT LENGTH, m Kg/KM)2 x Fc
TAKE MAXIMUM LAMINAR FLOW WIND SPEED AS 6,7 M/S
COMBINING ABOVE EQUATIONS GIVES
W = ½(CONDUCTOR TENSION, T Kn) 310
M (MASS PER UNIT LENGTH, m Kg/KM)2 x Fc
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Copyright 2010 Preformed Line Products • All rights reservedTelephone: 033 397 5800 • Facsimile: 033 387 7094Email: [email protected] Website: www.preformedsa.co.za
® Application Instruction – Dogboneand Multi-Reponse Damper
1. Position the Dogbone on to
the conductor as shown.
2. Align the centre mark of the first
retaining rod on the centre of
the hook. Crown 1 - and slightly
behind the crown so that the
rod pushes the hook against the
conductor
3. Wrap the retaining rod around
the conductor both sides of the
hook.
4. At this point, check that the rod
has been applied so that it
terminates on the inside of the
conductor bundle. Align the
centre mark of the second rod
on the hook crown approx
8mm away from the first one
and continue to wrap on the
second rod.T - 19
PLP – The connection you can count on
INDEX
Copyright 2010 Preformed Line Products • All rights reservedTelephone: 033 397 5800 • Facsimile: 033 387 7094
Email: [email protected] Website: www.preformedsa.co.za