Problem 74-4    Source:   Problem developed by the site author.

A 100 kV transmission line must be installed along a river bank. It is known that the river undergoes a dredging process periodically, in order to clean the along its course. The machines used do not work properly if they are exposed to magnetic fields greater than 4 µ T. If at peak energy consumption the current can reach values of 200 A, determine the minimum height of the transmission line (disregard the Earth's magnetic field).

Solution of Problem 74-4   

We must determine the height of the transmission line using eq. 74-17, already studied and reproduced below.

Making an algebraic arrangement, to determine the value of d , we have:

Carrying out the calculation, we find:

Note    - This calculated value is in relation to the terrestrial surface. As we know, the machines have a certain height and, in addition, we must have a safety margin. So, in a real project, a value suitable minimum would be d = 15 meters