/images/buttons/swirl_60.jpg/images/southwire_100x70.jpgSWRate Line Thermal Rating Tool Gets Important Updatesswrate-line-thermal-rating-tool-gets-important-updates.htmCritical updates in SWRate v4.1 improve calculation of steady-state and transient line ratings
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SWRate Line Thermal Rating Tool Gets Important Updates

Critical updates in SWRate v4.1 improve calculation of steady-state and transient line ratings

Southwire’s SWRate is a widely used software tool for calculating steady-state and transient line ratings for overhead conductors. The program ships with orders of Southwire’s Overhead Conductor Manual. Used jointly with Southwire SAG10®, SWRate allows for complete modeling of an overhead conductor.


New SWRate version improves accuracy, expands user choices

The newest version of SWRate, version 4.1, includes these upgrades:

  • Corrects the method for calculating solar heat gain during night-time hours. Previous versions of SWRate miscalculated solar heat gain as nonzero at midnight. This miscalculation gave an overly conservative line rating for periods when the sun was down. In v4.1, when the sun is down, solar heat gain is assumed to be zero. This yields higher line ratings for non-sunlit periods.
  • Expands users’ conductor choices, adding 3M Aluminum Conductor Composite Reinforced (ACCR), ACCR with trapezoidal wires (ACCR/TW) and more hard-drawn copper conductors.
  • Updates resistance values and weights for vibration-resistant VR2 conductors.
  • Limits wind angles to a range of 0-90 degrees.


Southwire keeps SWRate compliant with IEEE Standard 738

Southwire continues to keep its software up-to-date based on current knowledge of line rating calculation methods and evolving industry standards.

Specifically, Southwire is committed to keeping SWRate compliant with IEEE Standard 738, which covers calculation of current-temperature relationships in bare overhead conductors. SWRate versions 3.02 - 4.0 comply with the previous 2006 revision of Standard 738. When the proposed Standard 738-2011 is adopted, Southwire will be positioned to ensure that SWRate is compliant with it.

For more information on SWRate v4.1, contact Southwire here.