Load flow, short circuit, arc flash, protection coordination, the four studies every MV/LV project hands the consultant, all from one model and one source of cable and transformer data.
Build the SLD once with cable and transformer data. ETAP runs load flow, fault currents, arc flash, and TCC coordination from the same model, no duplicate inputs.
IEC 60364 limits voltage drop at 4% at the final circuit. ETAP highlights buses exceeding the limit in red. Transformer tap settings come out of this study, not a guess.
Output is cal/cm² at each bus. Above 8 cal/cm² needs Category 3 PPE. Saudi MV substations almost always exceed this on the line side, the study tells you where.
A single fault should trip one breaker, not the whole feeder. TCC plots show curves overlapping. Re-grade the upstream relay or change the fuse, then re-run the study.
The studies that have to land before commissioning.
| Study | Output | Used for |
|---|---|---|
| Load flow | Voltage drop %, kW losses | Cable + transformer sizing |
| Short-circuit | Isc kA, X/R | Switchgear breaking capacity |
| Protection coordination | Time-current curves | Selectivity, arc reduction |
| Arc-flash | Incident energy cal/cm² | PPE category, labels |
| Harmonic analysis | THDi %, IHDi per node | Filter / transformer K-rating |
| Motor starting | Voltage dip, torque vs speed | DOL vs VSD decision |
| Reliability assessment | SAIFI, SAIDI, ECOST | Critical-power architecture |
ETAP is the SLD that knows physics. Build it once, study it five times.
Use vendor-supplied .etap libraries for Schneider, ABB and Siemens transformers, breakers and motors. Generic IEC defaults are off by 5-15% for impedance, enough to mis-size a breaker.
Run 110% load, 90% voltage, summer / winter, and motor-starting transient. Saudi grid voltage swings 0.95-1.05 pu typical; design for the worst-case combination, not nameplate.
IEC 60909 Isc at every bus, then check each breaker's Icu and Ics against the calculated kA. Above the published Icu and the breaker explodes on a fault, a real and ongoing problem with imported gear.
IEEE 1584-2018 / NFPA 70E calculates incident energy and arc-flash boundary; the label states PPE category. Saudi LOTO regimes increasingly require these, install them in the build, not after the incident.
The ETAP curves drive relay settings; commissioning verifies them with primary injection. A curve that's selective on paper but un-commissioned trips the upstream breaker on every downstream fault.
Every NLC switchgear delivery includes an ETAP study suite (load flow, Isc, protection, arc-flash) and on-site commissioning by certified engineers. SEC connection-ready.
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