DC Arc Flash Analytic - Calculation example

Consider 256V DC panelboard with a 25mm gap between conductors, 36 milliseconds time constant 19,048 Amp short circuit fault current at its terminals. The gear is protected by Mersen 1200A 500V DC rated fuse part number A4BQ1200 located upstream. Incident energy at working distance, arc flash boundary and site-specific level of personal protection equipment (PPE) will be determined using DCAFA V3.0 software program based on DC arc flash modeling and NPFA 70E Standard for Electrical Safety in the Workplace. Start with specifying equipment class, gap between conductors, working distance, available short circuit current (ASCC), part of ASCC through protection device, circuit time constant and system voltage:

The program will automatically take care of determining predicted arcing current, and arc duration at the predicted arcing current through protection device based on the selected protection device time-current characteristic adjusted for the circuit time constant. See How to calculate incident energy and arc flash boundary of a DC arc flash for the detailed DC arc flash modeling information.

Click on Calculate button. The calculation results screen will appear. Click on Save Results button to save the calculations results. Select label size, language, header type, text color and click on Save as Image and/or Save as PDF button to save the label in one of the available electronic formats. You can also click on Printing menu button to fine tune printing options, preview and print warning labels.

By pressing Save Results button, the results will be saved to a text file for future reference or printing. You can save results for different jobs under different names. By choosing Open from File menu, you can open an existing results file, inspect its current content etc. If you need more complex editing, import the file into your favorite text manipulation processor (MS Word as an example) and do what you need to do.

You can fine tune units of measurement for input and output data by clicking on Units from Settings menu. The DCAFA V3.0 software program also allows you to adjust arc duration cutoff, incident energy at arc flash boundary values, save equipment configuration, and more. Please check the program Help for more information.