Cable Thermal Analysis

Neher-McGrath & IEC 60287 - Thermal Cable Current Capacity

The Cable Thermal Analysis module helps engineers to design cable raceway systems to operate to their maximum potential while providing a secure and reliable operation.

The advanced graphical interface allows for design of cable raceway systems to meet the existing and future needs by using precise calculations to determine the required cable sizes, their physical capabilities, and maximum derated capacity / ampacity. In addition, transient temperature analysis computes temperature profiles for cable currents, reducing the risk of damage to cable systems under emergency conditions.

Cable Thermal Analysis Key Features

Cable Steady-State Temperature Calculation using:

Neher-McGrath Method
IEC 60287 Method

Cable Transient Temperature Calculation
Cable Ampacity Calculation using:

Cable Sizing -Thermal Analysis
Underground (UG) Cable Raceway Rule Book
Electromagnetic Field Intensity Evaluation

Cable Thermal Analysis Capabilites

Printable cable, conduit and raceway layout.
Printable dimension indication for conduits and raceways
Graphical manipulation of raceways, cables, conduits, etc.
Drag & drop cables from one-line diagrams
Cables 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 metallic layer
Calculate thermal resistance, dielectric losses, conductor loss factor, metallic layer loss factor
User-defined cable physical structure
Unbalanced load factors
Multiple duct banks & direct-buried conduits
Place raceways in multiple cross-sections

User-Defined Cable Physical Structure

ETAP cable thermal analysis module can model single core and multiple core cable physical structure in details. Various cable thermal and metallic layer types and corresponding dimensions can be defined individually based on actual cable construction.

Insulation
Filler
Grounded/ungrounded metallic screen
Grounded/ungrounded metallic armor
Bedding
Grounded/ungrounded metallic sheath
Jacket

Flexible Operation

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

Plotting & Reporting

With the advanced web-based plot tools, the cable transient temperature plot can be generated and customized according to engineers’ requirement.

Interactively view and zoom the transient temperature plot to any detail levels
Option to combine and compare multiple transient temperature plots from different scenarios
Report all physical and calculated data into multiple file formats

Interactive User Interface

The enhanced interactive interface helps engineers to design and draw the raceway fast and intuitively. With the snapping guideline, conduits and raceways can be precisely located by dragging without entering the coordinates. Automatic dimension labeling expedites the generation of the raceway layouts without additional editing and annotating.

Display multiple cables, conduits, and raceways in the same presentation
Option to display raceway dimensions
Option to display Edge to Edge and Center to Center distance between conduits.
Flag critical & marginal cable temperatures
Snapping guideline between Centers, Tops, and Bottoms

The cable capacity / ampacity calculation and cable sizing are based on the NEC accepted Neher-McGrath method and IEC 60287 standard for steady-state temperature calculation. 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.

Standards / Method	Title
Neher-McGrath	The Calculation of the Temperature Rise and Load Capability of Cable Systems
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 60287-2-1:2015	Electric cables - Calculation of the current rating - Part 2-1: Thermal resistance - Calculation of thermal resistance
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