Catenary Curves for 72mm ADSS Fiber (Outside Aerial)

Of course, you asked the supplier?

Or, maybe: The Fiber Optic Association

Installing and Testing Fiber Optics - NECA - National Electrical ...

I don't have a clue, myself, but ↑

A catenary is a geometric shape. The equation doesn't change on account of voltage or composition of material that is hanging. A parameter or two will change on the length of material, which depends on temperature, but not the overall equation.

He is talking about sagging in the cable where you lay in the cable to handle different temperatures. The least clearance for a given length of cable is, or used to be, at 257^oF. The greatest tension, least sag, is at the lowest ambient temperature

I'm with Tornado, the catenary curve is the shape. It does depend on several input quantities though; things like lb per foot of the cable, tension, span, etc. Increasing temp will make the cable longer, thus more sag. I should have the equations here somewhere, but they should also be available "out there."

Definitionally, a catenary is specified completely by the locations of its endpoints and the length of the suspended item (assuming no interfering objects.) Weight per length doesn't affect the shape, but of course it affects the tension. One can "work backward" from the tension versus weight-per-length to find the total length and shape, but the length is the fundamental quantity.

Guys, what you say is correct but misses the OP's point.

When you design a transmission or distribution line, you pick a cable and based on its strength, figure a sag for each span for equal tensions (insulators hang vertically). Then the other conditions are checked for their effect on sag for that length of cable, icing for that district, high winds and high temperature. These days, these are handled simultaneously by a computer program. OP seems to be asking if the high temperature is appropriate for the fiber line since there is not a high current flowing.

I would say that the high temperature sag can be ignored.

I would say that the high temperature sag can be ignored.

I don't think so. Is this communications cable going to be exposed to the sun and weather? The expansion due to temperature change will definitely affect the sag.

It will have a high temperature sag, but not as high as for a transmission line carrying maximum current on a hot day. The sag tables/programs cover other temperature steps as well as the extreme.

Hey guys,

Thanks for all the responses. Doing a little more research "out there" the sag for Fiber Comm wire is negligible, ie. most companies won't even bother to create a sag chart/drawing. Typically for 12kv, 60kv, Transmission, Distribution, we WILL create charts due to the SIMPLE FACT that these are current carrying conductors and (based on loading) will have (at some points) significant sag (3, 4, 5 feet). The heat that is generated by the load will cause the wire to sag more (also will make it eventually more brittle), then maintenance will get the job...

Thanks for all the input guys.