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Reactance of Overhead Line (with neighbouring o/h line)

Reactance of Overhead Line (with neighbouring o/h line)

Reactance of Overhead Line (with neighbouring o/h line)

(OP)
We have an O/H 3ph distribution line @ 72kV arranged with post top insulators. At a lower elevation, a horizontal crossarm is being used to carry a 3ph, 25kV line.

Now my question is: Will the 25kV line have an influence on the 72kV line reactance? How do I calculate the reactance of the 72kV line? The shield wire is right on the top of the pole and is common for both the 72kV & 25kV lines.
I am comfortable with the formula for 3ph line reactance with GMR and GMD values. Here since Ia = - (Ib + Ic), the equation gets reduced.

However, for the case above, since 25kV and 72kV lines are electrically separate, I am guessing that the 25kV line amp load will have an impact on the reactance of the 72kV line.

Any help on this issue is appreciated.

RE: Reactance of Overhead Line (with neighbouring o/h line)

If the 25kV is separated from the 72kV by delta windings in transformers, then the only part of the 25kV that would affect the 72kV is the neutral. If the shield is the neutral you probably have it all already. If there is a zero sequence path between the two systems (wye-wye transformers), you will see some zero sequence mutual coupling. Refer to Anderson's Analysis of Faulted Power Systems.

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