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Re: [TowerTalk] Guy wire / Phillystran vibration

To: <>, "Chuck Kraly" <>
Subject: Re: [TowerTalk] Guy wire / Phillystran vibration
Date: Tue, 6 Jan 2004 19:28:15 -0500
List-post: <>
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 
  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.".


  ---- 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,

  > 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.
  >  Jeffâs 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 didnât 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

      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
  of the span that does the same thing. I'm sure you've been driving along
  power lines and have seen those little trianglular devices hanging on the

      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 or dancing is a wind-related phenomenon when low frequency, high
  amplitude wind-induced motion can cause trip-outs, service interruptions,
  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

  Air Flow Spoilers maintain aerodynamic stability by continually changing the
  profile of the cable to the wind. The one-piece helically formed rod, made
  rigid, non-corrosive, non-metallic plastic, controls motion problems that
  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
  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
  Spoilers. A placement scheme will be returned to determine placement of Air
  Spoilers in each span. Please advise whether the cables contain optical
  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
  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
  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

  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.

TowerTalk mailing list

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