How Shermco uses ETAP digital modeling to accelerate power system studies for data center expansion projects

The ETAP platform’s integrated workflow let us evaluate short-circuit, coordination, AC and DC arc flash within a single model, eliminating manual transfer steps and reducing analysis time significantly.
Chris Inshaw, Senior Power Systems Engineer at Shermco

This case study highlights how ETAP enabled accurate short-circuit and equipment duty evaluations, protective device coordination, and AC & DC arc flash analyses for the complex architecture for a data center project. The use of ETAP for integrated modeling and analysis identified critical design issues while also reducing engineering effort.

Shermco is a premier electrical services provider with more than 40 service centers across North America. They specialize in technically advanced field, shop, engineering, and control services. Trusted since 1974, the company helps clients to enhance safety and reliability by delivering data, insights, and solutions that extend the lifespan of their critical infrastructure.

Location: Irving, Texas, USA

Year: 2021

Ensuring rapid delivery of accurate calculations and in depth studies

Challenges

1. Complex AC & DC electrical architecture

  • Multiple UPS modules, battery cabinets, PDUs, and MV feeds
  • Need for accurate modeling of both AC and DC systems, including nonlinear components

2. Relay coordination issues

  • Lack of selectivity between utility relays and site relays
  • Ground fault functions effectively disabled due to high-resistance grounding

3. High-risk DC arc flash environment

  • Initial DC Arc Flash results > 125 cal/cm² using the Maximum Power Method
  • Misidentified battery disconnect type and inadequate internal shielding

4. Multiple operating modes

  • Normal, standby, generator configurations required scenario analysis
  • Need to validate safe operation across all configurations

Which solutions did they choose?

Selected applications

ETAP was used to perform:
  • Short-Circuit & Equipment Duty Evaluation
  • Protective Device Coordination (TCC)
  • AC Arc Flash (IEEE 1584-2018)
  • DC Arc Flash (NFPA 70E-2018; Stokes & Oppenlander Method)
  • Digital Twin Modeling for scenario validation

For this project, Shermco conducted a study on short circuit and equipment evaluation, protective device coordination, and AC and DC Arc Flash. For the calculations of AC and DC Arc Flash, we used standards based on the IEEE 1584 and NFPA 70E. The analysis also included the existing UPS distribution and its modules. The consultant created the model using ETAP based on the submittal customer data of the existing system model, and the data provided by the client. In the model, medium-voltage distribution and standby sources were included, with multiple configuration paths, to accommodate the various switching configurations available at the site. 

Why do they use ETAP?

Main customer benefits

1. Accurate short-circuit modeling under all switching conditions. The ETAP Digital Twin captured the medium-voltage normal and standby paths, enabling duty evaluations for every UPS module, PDU, and feeder. All equipment was confirmed adequately rated.

2. Identification of relay miscoordination and improvement path. Coordination studies revealed insufficient time intervals between upstream utility relays and site relays. ETAP TCC tools allowed rapid visualization of miscoordination and definition of optimized protection settings to implement during the next outage window.

3. AC arc flash results validated safe operational boundaries. Across all feasible operating modes, incident energy remained below 40 cal/cm², supporting safe maintenance conditions using standard PPE categories.

4. Resolution of a critical DC arc flash hazard. ETAP revealed that the battery cabinets’ internal configuration and disconnect type produced extreme incident energy levels:

  • Initial result: ~125 cal/cm² (Maximum Power Method)
  • Refined result: ~22–23 cal/cm² (Stokes & Oppenlander Method)
  • Optimized recommendation: <1.2 cal/cm² with HLDC disconnect replacement

These findings were only possible through ETAP’s detailed DC modeling and method selection tools.

5. Improved equipment specifications and long-term safety. Engineering recommendations included:

  • Replacement of LGDC disconnects with HLDC fixed-instantaneous models
  • New procurement specs requiring disconnect operability with covers in place
  • Updated criteria for future UPS and battery cabinet installations

6. Streamlined workflow and dramatic time savings

Before ETAP, analysis required:
  • 45 hours short-circuit
  • 85 hours coordination
  • 130+ hours manual arc flash consolidation

 

By using ETAP software, with its full connection between power system modeling, simulation and analysis, avoided more than 260 engineering hours, while improving accuracy and consistency.

 

Conclusion

The ETAP digital modeling environment provided a comprehensive view of the data center’s electrical system, revealing critical miscoordination issues and a significant DC Arc Flash hazard that traditional methods had overlooked. The results enabled:
  • Accurate risk categorization
  • Optimized protection strategies
  • Safer equipment specifications for future expansions
ETAP allowed the engineering team to validate every scenario with confidence, ensuring both regulatory compliance and long-term operational reliability.

What do they think about ETAP?

Customer perspective

ETAP allowed us to accurately model the large-scale electrical architecture of the expansion, including the medium-voltage distribution and battery systems. ETAP provided insights that directly shaped equipment specifications and improved personnel safety. 
- Chris Inshaw, Senior Power Systems Engineer, Shermco


Videos

Data Center Power System Expansion: DC Arc Flash Case Study

Case study of a a power system study, which involved the replacement of an extensive UPS system at a data center. 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 2027 and IEEE 1584 2018 Standards. The DC equipment as installed required mitigation efforts due to high incident energies. This presentation details the analysis, findings, and recommended mitigation for anyone embarking on similar retrofit or expansion studies.


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