Has anyone experienced Medium volat
Has anyone experienced Medium volat
(OP)
Has anyone experienced Medium volatge cable failure due to excessive Sidewall Bearing Pressure during pulling?
Other comments on max Sidewall Bearing Pressure would be appreciated.
Other comments on max Sidewall Bearing Pressure would be appreciated.






RE: Has anyone experienced Medium volat
RE: Has anyone experienced Medium volat
I hate to admit it, but we pulled a cable two years back where we maxed at 6000lbs with many bends through out, and the cable has been happily energized since. (34.5kV)
Am I misinterpreting the restraint imposed by the sidewall bearing pressure, or was I just lucky with this other pull that it hasn't failed.
All of the bends are 2 foot radius pulleys, and the installation is in convoluted tray through an existing building.
RE: Has anyone experienced Medium volat
Most cable failure occur because of damaged done during installation. Sidewall pressure is a big factor and mechanical dammage during handling ( like getting stepped on kinked or run over ) is another common cause.
I think manufactures are setting the mazimum side wall pressure lower and lower. Ten or so years ago figures like 900 lbs were common and now 300 is the norm. It varies with insulation and shied type. XLP with a wire shield you is almost idiot proof. Some rubber compound with a tape shield are more delicate.
Southwire has the calculation and formulas on there website. If your there get a copy of their cable manual ( useful and free ) Okonite has good technical data on theri site and a "Cable Installation Manual" that you can get from your local rep.
I think I've said it on this site befor that the Polywater "Pull Planner" program is very good and about $100 ( maby free if you buy a lot of lubricant from them). If you have a critical pull it's worth buying. It's also worth buying if you work for an owner who want's documentation that you know what your doing.
What are the parameters of your 35 KV cable - tape or wire shielded? A 2' bend radius is close to the minimum static bend for a 500 or 750 mcm cable with a spiraled tape shield.
RE: Has anyone experienced Medium volat
Thank You,
Gord
RE: Has anyone experienced Medium volat
I am sure XLP did have a higher sidewall pressure and I believed they reduced the allowabel because of all the trouble they were having with premature failure of URD cable because of "treeing".
The actual configuration of cable - triplexed vs cradeled has a lot to do with the actual sidewall pressure on any particular conductor. The usual methods of calculating this consider the worse case so there is plenty of slop in them. The Okonite Installation Manual and the Soutwire Power Cable Manual have good write ups on this. I cannot find the complete Okonite or Southwire ( southwire you can order on line) manuals on line so you probably have to go to your local rep to get them.
This is a good link from Polywater on the subject.http://www.polywater.com/techtak1.html
RE: Has anyone experienced Medium volat
RE: Has anyone experienced Medium volat