These guidelines are specifically designed for electrical systems in EMEA, Asia and Latin America (non UL).
The UPS is supplied by AC and DC sources. Unlike the short circuit current generated by the AC sources, generally predictable, the short circuit current generated by the battery is variable and not easily predictable. With an unpredictable fault current the selection of the rating of the protection is quite challenging.
The purpose of this document is to go more in depth in the analysis of the current delivered by the battery and the selection of the proper protection.