calcuation of sag and cable span

catenary

Which is a hyperbolic function.

Travis

Is this a trick question?

<...how to calcualte the sag and span of a aerial telcom cable....>

The catenary equation is that of the hyperbolic cosine mathematical function. The rest is arithmetic.

For level span sags, an approximate parabola equation can be used for span lengths below 300 meters (1,000 ft) or where sag is less than 5% of the span length.

S = WcL²/8Th

where:

S = sag at center of span in meters (ft), Wc = conductor weight in Newtons per meter (lbs per foot), [for standard gravity 1 kg = 9.81N), L = span length in meters (ft), and Th = horizontal tension in Newtons (lbs).

The exact formula for determining level span sag is:

S = Th/Wc (cosh WcL/2Th - 1)

The wind force on cylindrical surfaces can be calculated:

Pressure in lbs/ft² = 0.00256 (v)² where v = wind velocity in miles per hour or:

Pressure in pascals = 0.613 (v)² where v = wind velocity in meters per second.

That force is applied to the exposed area (diameter) of the cable.