Creating T2 Conductors for Use with PLS-CADD and PLS-CADD/Lite
PLS-CADD and PLS-CADD/Lite can easily model T2 (Twisted Pairs) or VR (Vibration Resistant) conductors.
This TechNote will describe how to set up your conductor data to accommodate T2 conductors.
This topic is also covered in the PLS-CADD Manual.
- First, obtain the information for the single subconductor to be used in the T2 conductor. This can be obtained from your own standards, your conductor manufacturer, or may even be downloaded from our website here.
- Next, in PLS-CADD or PLS-CADD Lite, select the Sections / Edit Cable Data menu item and pick the single subconductor data file.
- Now modify the conductor properties as follows;
- Multiply the cross section area, AT, by two.
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Multiply the outside diameter, D, by the diameter exposed to the wind. Since this changes continuously along the conductor, an average equivalent circular diameter equal to 1.64 times the subconductor diameter can be used (Roche, J.B. et al.,
"T2 Wind Motion Resistant Conductor", IEEE Transactions on Power Apparatus and Systems, Vol. PAS-104, No. 10, Oct. 1985). According to the reference, the equivalent diameter will also provide a good estimate of ice load based on ice thickness.
- Multiply the unit weight, UW, by two.
- Multiply the ultimate tension, ULT, by two.
- The number of independent cables, n, should be left at one (1).
- The stress-strain and other properties should be left the same as those for the single subconductor.
- If thermal properties are being used, reduce the resistance values by half the resistance of a single subconductor.
- If thermal properties are being used, multiply the heat capacity values by twice the heat capacity of a single subconductor.
- Click on the "OK" button and be sure and save your cable file name as something different than your subconductor file. We would suggest something like "drake_t2.wir" for the file name.
- Finally, when stringing the conductor, the number of conductors per phase should be one, since both of the subconductors of the twisted pair are modeled together in the conductor properties.
These simple modifications to your subconductor file allow you to easily model T2 (or VR) conductors with PLS-CADD and PLS-CADD/Lite.
