331.4 kW
Base source power
Executed balanced AC base case
Engineering case study
Small Commercial Facility Power Distribution Design and Analysis
Preliminary 12.47 kV-to-208/120 V radial distribution study for a synthetic 35,000 ft² office and warehouse.
- Executed simulation
- Analytical calculation
- Automated test
Problem statement
Develop an explainable small-facility distribution architecture and test whether preliminary transformer, feeder, and panel choices remain acceptable across normal and stressed operating conditions.
An executable educational design that connects a load schedule and preliminary equipment sizing to AC load flow, voltage-drop checks, phase allocation, and fault-current analysis.
0.952 p.u.
Base minimum voltage
Barely above the 0.95 p.u. planning target
0.927 p.u.
Future minimum voltage
110% existing load plus 30 kW future allowance
16.2 kA
Maximum 3-phase fault
Modeled at the 480 V main switchboard
Project scope
- 12.47 kV utility equivalent, 750 kVA service transformer, and 480Y/277 V distribution
- 150 kVA derived 208Y/120 V system for receptacle, IT, kitchen, and future loads
- Synthetic load schedule, feeder assumptions, four operating scenarios, and preliminary protection hierarchy
- Balanced positive-sequence analysis; not a construction or permit design
System or processing architecture
A radial utility-to-service-transformer topology supplies a 480 V switchboard, motor and lighting panels, and a downstream delta-wye transformer feeding two 208/120 V panels. Phase allocation is checked separately from the balanced network solution.
My engineering contributions
- Built the load schedule and translated connected kW, demand factors, and power factor into kW, kvar, kVA, and current.
- Implemented the pandapower network, scenario runner, IEC 60909 three-phase fault study, and result exports.
- Used execution results to correct an undersized upstream feeder and improve single-phase load allocation.
- Produced the one-line, calculation workbook, engineering report, validation checklist, and hand-calculation checks.
Important design decisions
- Used 480 V for larger three-phase loads and 277 V lighting to limit current while deriving 208Y/120 V for common utilization loads.
- Selected a radial topology so load paths, protection boundaries, and failure assumptions remain inspectable.
- Kept the single-line-to-ground value explicitly approximate because utility and equipment zero-sequence data are unavailable.
Engineering methods
- Demand-load and three-phase current calculations
- Conductor R/X voltage-drop calculations
- Newton-Raphson balanced AC power flow
- IEC 60909 positive-sequence short-circuit analysis
- Independent transformer-terminal fault and phase-balance checks
Selected evidence
Readable results, with context
Verification and testing
- All four published power-flow cases converge and retain traceable bus and feeder outputs.
- Automated checks cover current, transformer fault current, voltage drop, and phase balance.
- A 7.24 kA transformer-only hand estimate correctly bounds the 5.97 kA detailed 208 V network result.
- Generated CSVs, figures, workbook, and report are rebuilt from the same source assumptions.
Honest limitations
- Synthetic facility and utility data; no site survey, field measurements, professional seal, or AHJ review.
- Balanced load flow does not resolve neutral current, unbalance, harmonics, or motor starting.
- No device-curve coordination, arc-flash calculation, exact grounding study, or construction drawing set.
- Feeder ampacity and interrupting selections require the adopted NEC, equipment data, and licensed-engineer review.
Tools and technologies
- Python
- pandapower
- pandas
- NumPy
- Matplotlib
- Excel
- IEC 60909 concepts
Skills demonstrated
- Power distribution
- Load flow
- Short-circuit analysis
- Equipment sizing
- Voltage drop
- Engineering documentation
Downloadable proof of work
Review the evidence directly
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