Introduction
Read this case study from ETAP. It explores a recent power system study involving the replacement of an extensive UPS system at a data centre. This presentation details the analysis, findings, and recommended mitigation for anyone embarking on similar retrofit or expansion studies.
Key Challenges
The studies included short-circuit, protective device coordination, and arc-flash hazard analysis for both the AC and DC systems consistent with the NFPA 70E 2018 and IEEE 1584 2018 Standards. The DC equipment as installed required mitigation efforts due to high incident energies.
After consultation with Client and Engineer of Record regarding the results of DC Arc-flash it was agreed that the Maximum Power method was possibly over/under conservative in two areas:
- Assumes arcing fault current is fixed at 50% of bolted-fault current.
- Assumes a 3x multiplier for an arc in a cabinet.
The Solution
Analysis was re-run using the Stokes & Oppenlander method with substantially improved results due to a more accurate determination of arcing fault current and the effect of an enclosure.















