Transmission lines/Substations - Unlevelled span with concentrated loads (insulator chains) forces

[NoFaultRequired]

Hello there, hope you guys are doing fine;

I've been working at substation eletromechanical design for some time and I've never seen an algebraic method for calculating unlevelled short spans with insulator chains (taken as concentrated loads) forces.

Have anyone of you seen some solution for this actually common situation in substation design?

Most of the reference books out there will be treating the problem of transmission line spans without insulator chains or if the chains are considered, only levelled spans are taken into account. None of them seem to consider the substation case, with a short span and tensioning insulator chains.

I'm wondering that transmission line design softwares (e.g.: PLS-CADD) may do some kind of finite element modelling for these situations, but I've never used this kind of sw.

Here's an actual example of the situation, where the difference in height between fixing points is 9,35 meters and the span has 55,00 meters. Also the insulator chain weight is almost the same as the total conductor weight along the span.

Thanks for your attention,

Best regards.

 

[bacon4life]

PLS-CADD does have capability to model insulator strings as well as other kinds of point loads like marker balls and vibration dampeners.

The first time I modeled a substation bus in PLS-CADD, the Lidar survey points of the conductor did not at all match up to a ruling span approximation. It was relatively straight forward to do enough hand calculations to convince myself that a simple ruling span assumption was inadequate for heavy insulator strings. Updating the PLS-CADD model to use finite element analysis with approximate insulator weights got the model to align with Lidar pretty well.

My project involved swapping out porcelain insulator for polymer insulators. Polymer insulator weigh so much less that the new design did not need to specifically model the insulator weight.