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Underground Thermal Analysis - Cable Thermal Software


Cable Thermal Analysis Software
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As a cable thermal calculation software, ETAP allows users to run the following calculations:

In order to facilitate the initial setup, the underground raceway system allows you to drag and drop cables directly from the one-line diagram and also allows you to create underground raceway systems such as duct banks using ETAP Rule Book. ETAP’s cable thermal assessment software is an excellent tool to compute Cable Ampacity based on Load Flow calculations and cable sizes based on the Cable Sizing analysis tool.

Cable Layers


  • Lead Sheath
  • Aluminum Sheath
  • Steel Armor/30dg/15w
  • Steel Armor/30dg/20w
  • Steel Armor/30dg/25w
  • Steel Armor/45dg/15w
  • Steel Armor/45dg/20w
  • Steel Armor/45dg/25w
  • Steel Armor/45dg/30w
  • Steel Armor/45dg/40w
  • Steel Armor/45dg/50w
  • Steel Armor/45dg/60w
  • Steel Armor/45dg/70w
  • Steel Armor/45dg/80w
  • Steel Armor/45dg/90w
  • Steel Armor/45dg/100w
  • Steel Armor/45dg/9999w
  • Copper Armor
  • Steel Armor
  • Aluminum Armor
  • Copper Concentric Wire
  • Aluminum Concentric Wire
  • Copper Sheath

ETAP underground duct bank analysis program can be used to compute the effect of duct banks or conduits based on cable steady-state and transient temperatures. Underground duct bank analysis software allows direct-buried cable systems surrounded with soil as well as cables in conduits surrounded by a raceway (e.g. concrete) with different thermal resistivity than the surrounding soil. These features make ETAP the state-of-the-art cable thermal analysis program.

Cable Thermal Analysis Software - Underground Raceway Systems
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      Underground Cable Thermal Analysis

Cable Layers


  • Graphical user interface
  • Graphical manipulation of raceways, cables, conduits, etc.
  • Intelligent rule-based alignment & spacing tools
  • Automatic conduit distribution & spacing
  • Uniform & non-uniform conduit arrangements
  • Wizard for creating raceways with rule-based spacing
  • Custom, NEC or ANSI rule-based spacing
  • Drag & drop cables from one-line diagrams
  • Cable of different sizes in the same raceway
  • Separate phases into different conduits or locations
  • Unsymmetrical positioning of raceways
  • Transient calculations use a dynamic thermal circuit model
  • Option to fix cable size and/or loading
  • Grounded/ungrounded shielding
  • Calculate thermal R, dielectric losses, Yc, Ys, etc.
  • User-defined armor cables
  • Unbalanced load factors
  • Multiple duct banks & direct buried cables
  • Place raceways in multiple cross-sections

Flexible Operations


  • Multiple raceways
  • Multiple external heat sources
  • Optimization of new cables in existing raceways
  • Cross-sectional analysis
  • Duct banks & direct buried raceways
  • Integrated with cables in one-line diagrams
  • Integrated with load flow results
  • Integrated with cable pulling analysis

Display Options and Plotting


  • Display conduit percent fill information directly on the underground raceway cross-section
  • Display cable loading and cable steady-state temperature directly on the underground raceway
  • Transient temperature calculations based on load profile
  • Option to display multiple cables simultaneously
  • Zoom to any detail level
  • Export data to Microsoft Excel
  • Line, bar, 3-D, & scatter plots
  • Customize text & axes



  • Flag critical & marginal cable temperatures
  • Reports all physical & calculated data
  • Use Crystal Reports for full color, customizable reports
  • Export output reports to your favorite word processor
  • Graphical display of raceway results

Cable derating analysis is an important part of power system design and analysis. When the goal is to design a new system, this module determines the proper size of cables to carry the specified loads. When performing the analysis of an existing system, this cable thermal analysis software examines cable temperatures and determines their ampacity.

ETAP cable thermal analysis program provides five types of calculations for cable derating analysis, namely, steady-state temperature calculation, uniform-ampacity cable ampacity calculation, uniform-temperature cable ampacity calculation, cable sizing, and transient temperature calculation. The steady-state temperature calculation is based on the IEC 60287 or the NEC accepted Neher-McGrath method.

The IEC 60287 steady-state temperature calculation fully complies with the latest standards as listed below:

Standard Title
IEC 60287-1-1 Ed. 1.2 b:2001 Electric cables - Calculation of the current rating - Part 1-1: Current rating equations (100% load factor) and calculation of losses - General
IEC 60287-2-1 Ed. 1.1 b:2001 Electric cables - Calculation of the current rating - Part 2-1: Thermal resistance - Calculation of thermal resistance
IEC 60287-2-1 Amd.1 Ed. 1.0 b:2001 Amendment 1
IEC 60287-2-1 Amd.2, 2006-03 Amendment 2
IEC 60287-3-1 Ed. 1.1 b:1999 Electric cables - Calculation of the current rating - Part 3-1: Sections on operating conditions - Reference operating conditions and selection of cable type
IEC 60287-3-1 Amd.1 Ed. 1.0 b:1999 Amendment 1

The cable ampacity calculation and cable sizing are based on the NEC accepted Neher-McGrath method only. The transient temperature calculation is based on a dynamic thermal circuit model. All of these calculations can handle multi-raceway systems and consider the effect of heat generated by neighboring cables and external heat sources.