The Determination of Sag and Tension in Transmission Line Spans and an Estimate of the Cost of a Typical Transmission Line System (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1914 edition. Excerpt: ... Chapter IV. A Graphical Solution for Spans with Supports at Different Levels. The ideal method for determining the resultant sag and tension under different loads or temperatures should be conveniently applicable not only to level supports but also to non-level supports. Hone of the methods that have been mentioned are conveniently applicable to the case of non-level supports. Hon-level supports are, however, not infrequently encountered in a transmission system, and therefore a more practical method of computation for such cases becomes desirable. The new method is devised to meet this requirement and to do away with complex equations and tedious calculations. In the case of level supports the sag, or deflection, of a transmission line is measured by the difference in height of the lowest point of the catenary, the vertex, and the point of support. With the supports at different heights the vertex lies no longer in the middle, but moves from the middle towards the lower support. In this case let the sag be defined as the difference in elevation of the point of higher support and of the vertex of the catenary. With non-level supports the calculation of the sag and of the horizontal distance from the vertex to either point of support for a given tension, span length, and load is not very simple, as the solution of the catenary equation must be made by trial. Moreover, as the temperature and load change, the horizontal distance of the vertex from the points of support shifts. This adds to the difficulty of determining the effect of changes in load and temperature upon the tension and sag. When the tension "T" and load "W" are given, the laborious calculations involved in a solution for the sag and the position of the vertex by trial can be...