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Re: [TowerTalk] Guy wire / Phillystran vibration

Subject: Re: [TowerTalk] Guy wire / Phillystran vibration
Date: Wed, 07 Jan 2004 00:55:40 +0000
List-post: <>
I don't want to take away from the guy vibration eliminators; supposedly they 
do work but they only reduce vibration induced into the guys from the wind.  I 
think the original posters of this thread were seeing vibration from the 
antenna being tranmitted into the entire tower/guy system and that was their 
original question.  If that is the case, that the antenna is causing the 
vibration and that is being transmitted into the system, then these wind 
vibration eliminators will do no good.  Correct folks?  I have a Rohn 45 up 120 
ft with a 3 el KLM 40M yagi up top , with Polygon guys, and the system is rock 
solid and yes I do have a Loos gauge and the guys are tensioned up to 10% of 
the strength of the weakest part which is the EHS at the bottom (~1100 lbs) and 
I've seen no undo vibration.  If it's the antenna causing the problem, then the 
posters should look into reducing that.  My 2 cents, Phil  KB9CRY
> The last time I bought direct from Phillystran they also sold dampeners, 
> solid 
> gray coils several feet long that wrap around the guys every so many feet 
> (about 
> 20 I'd say).  They have been on a 118' Rohn 45 for 15 years or so and I've 
> never 
> noticed any vibration problems.  73 - Rich, KE3Q
>   ----- Original Message ----- 
>   From: Chuck Kraly 
>   To: 
>   Sent: Tuesday, January 06, 2004 1:19 PM
>   Subject: Re: [TowerTalk] Guy wire / Phillystran vibration
>   One MAJOR difference, and why they are used on utility feeder lines......The
>   power lines have Slack/Sag put in when they are installed. Therefore, there
>   is a much better chance of the galloping. If you have slack on the guys
>   equivalent to a power line.....then IMHO something is wrong...hihi. Where I
>   work, we only use the dampeners on river crossings. But, I have seen a 161kv
>   line gallop and due to a misjudgment by an old time foreman, send a guy
>   about 30 ft in the air when he was told to "throw a rope around it and see
>   what you can do". Not a smart the lineman's aerodynamic
>   properties were equal to a rock, and followed the adage that "What goes up,
>   MUST come down.".
>   Chuck/K0XM
>   ---- Original Message ----- 
>   From: <>
>   To: <>; <>
>   Cc: <>; <>
>   Sent: Tuesday, January 06, 2004 11:44 AM
>   Subject: Re: [TowerTalk] Guy wire / Phillystran vibration
>   In a message dated 1/5/04 6:26:16 AM Pacific Standard Time,
>   writes:
>   > Question about guy wire vibration.  K4JNY and I were doing tower work
>   >  at his place all day Sunday and have noticed that on our 120â?? Rohn 45
>   >  that we are experiencing quite a bit of vibration to the tower and guys
>   >  that we believe is being transmitted down the tower by the 4 el 40m
>   >  beam at the top.   This vibration occurs at wind speeds of 10 mph or so
>   >  or higher.
>   >
>   >  Jeffâ??s first thought was that guy wire tension was too high, but
>   >  checking with the tension gauge resulted in only 2 of the 9 being too
>   >  tight â?? loosening them didnâ??t seem to mute the vibration on them 
> much.
>   >
>   >
>   >  The guys are EHS at the 40â?? level, and EHS for the bottom third and
>   >  Phillystran top two thirds for the guys at 80â?? and 120â??.
>   >
>   >  Our concern is that the Phillystran is not going to respond well,
>   >  long-term, to vibration.   Can excessive vibration be an early failure
>   >  problem for Philly guys?
>       Interesting question. I would say that the wind induced harmonic
>   vibrations wouldn't do much if anything to the Phillystran but would play
>   havoc with
>   the attendant hardware - i.e. shackles, tower guy attachment, rotator
>   hardware,
>   etc.
>       This is a common problem with utility lines - especially if they're long
>   span. What you need to do is to change the resonant frequency of the guy.
>   Typical fixes add some sort of weight to the cable or have a device in the
>   middle
>   of the span that does the same thing. I'm sure you've been driving along
>   some
>   power lines and have seen those little trianglular devices hanging on the
>   wire.
>       Preformed Line Products makes a Air Flow Spoiler that wraps around the
>   cable. Here's what they say about them:
>   >>  Air Flow Spoilers are designed to counteract the damaging effects of
>   galloping.
>   Galloping or dancing is a wind-related phenomenon when low frequency, high
>   amplitude wind-induced motion can cause trip-outs, service interruptions,
>   cable
>   damage, damage to supporting structures, and damage to support hardware at
>   their point of connection. High winds combined with cold weather and ice
>   accumulation are the main contributors to galloping on regular cables. The
>   accompanying ice build-up and wind can cause cable failure and structural
>   damage.
>   Air Flow Spoilers maintain aerodynamic stability by continually changing the
>   profile of the cable to the wind. The one-piece helically formed rod, made
>   of
>   rigid, non-corrosive, non-metallic plastic, controls motion problems that
>   can
>   damage lines. The three-section structure of the Air Flow Spoiler enables it
>   to grip the cable or conductor firmly.
>   Several Air Flow Spoilers are required in each span to offset the
>   aerodynamic
>   lift forces which cause galloping.
>   The number and placement of Air Flow Spoilers in each span are determined by
>   a computer program which considers the results of on-going field and
>   laboratory research. An Air Flow Spoiler Placement Request should be
>   completed and
>   returned to Preformed Line Products Company prior to installation of Air
>   Flow
>   Spoilers. A placement scheme will be returned to determine placement of Air
>   Flow
>   Spoilers in each span. Please advise whether the cables contain optical
>   fibers.
>   This may influence Air Flow Spoiler Selection.
>   Our Air Flow Spoilers are made of a rigid, non-metallic, non-corrosive
>   thermal plastic. The unique design of the PREFORMED Air Flow Spoiler
>   maintains
>   aerodynamic stability be providing a continually changing profile to the
>   wind. This
>   helps to dramatically reduce the incidence of galloping on lines. >>
>   >
>   >  Any other concerns with this situation we should be aware of?   Aside
>   >  from the loosening of connections, antenna hardware, etc. â??  our
>   >  concern is for the tower and the guys itself.
>       Since longterm vibration can cause fatal tower problems (and we all know
>   what it can do to antenna elements!), you need to figure out some way to
>   dampen the vibrations. Doing with the guys already installed makes it
>   somewhat
>   problematic. I'd live with it for the short-term and come up with some plan
>   to fix
>   it this summer.
>       I couldn't find anything specifically in the Phillystran info I have but
>   you might want to talk to Ken Knight, the Phillystran sales guy that's at
>   Dayton every year. He's at - tell him I sent you.
>   Cheers & GL,
>   Steve     K7LXC
>   Professional tower services for commercial and amateur
>   888-833-3104
>   _______________________________________________
>   See:  for "Self Supporting Towers", "Wireless
>   Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
>   questions and ask for Sherman, W2FLA.
>   _______________________________________________
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>   _______________________________________________
>   See:  for "Self Supporting Towers", "Wireless 
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any 
> questions and ask for Sherman, W2FLA.
>   _______________________________________________
>   TowerTalk mailing list
> _______________________________________________
> See:  for "Self Supporting Towers", "Wireless 
> Weather 
> Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions 
> and ask for Sherman, W2FLA.
> _______________________________________________
> TowerTalk mailing list

See:  for "Self Supporting Towers", "Wireless Weather 
Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions 
and ask for Sherman, W2FLA.

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