cable systems software
cable thermal analysis software
uniform ampacity calculation
Uniform Ampacity – Ampacity Calculation Software
The uniform-ampacity calculation method involves an iterative process of cable temperature calculation and load adjusting. This method is part of the overall cable thermal analysis software incorporated into ETAP.
This cable ampacity calculation method is based on the equal loading criterion for ampacity calculation. It determines the maximum allowable load currents when all the cables in the system are equally loaded to the same percentage of their base loading. The base load is obtained from the Cable Library for the appropriate system configuration type, such as duct bank or directly buried raceways.
The cable ampacity calculation involves an iterative process of cable temperature calculation and load adjusting, as listed below.
- Determine an initial loading level based on the base ampacity from the Cable Library and using cable derating factors for the given configuration.
- Calculate cable temperature as in the steady-state temperature calculation described above.
- Check cable temperature values against the cable temperature limit.
- If the temperature of the hottest cable is within close range of the temperature limit, the solution has been reached. If not, adjust the cable loading uniformly at the same percentage, either increasing or decreasing the loading in order to make the highest cable temperature come closer to the temperature limit. Then go to back to step 2 to recalculate cable temperature.
If the Update Currents from Ampacity Calc option is checked in the study case, the cable allowable current is updated by the calculated ampacity.