Stringing Charts For River Crossings

Final stringing charts are prepared on the basis of sag and tension calculations at different temperatures under no-wind condition for a particular proposal as per Annexure-1. These charts give final values of sag and tension which should never be exceeded on a line.
The stringing should be done as per initial stringing charts which are prepared after taking into account creep correction for the conductors. For earthwire no creep correction is required.
The stringing charts for river crossings are prepared from anchor tower to anchor tower only.
Sag indicated in the stringing charts are with respect to higher tower is determined as follows for cases where there is level difference between two towers.
Sag at span = {2a / L}2 x Sag at particular temperature for crossing span.
where,
a = L / 2 + TH / WL
where,
L = Crossing span Cm)
T = Tension at particular temperature under No-wind for equivalent span (kg)
h = Difference of R.L. of towers, (m)
W = Unit weight of conductor/Earth wire. (kg/meter)
For cases where there is no level difference, the value of sag given in the stringing chart for the corresponding crossing span may be adopted