Calculations

Discipline-by-discipline engineering calculations — electrical, HVAC, acoustic, seismic, fuel, pressure. Licensed software plus empirical validation. No skipped numbers.

Right standard for every discipline. Right calculation for every path. No skipped numbers.

Most engineering firms “size” — they pick a rated power, mark a model from the catalogue and move on. But making a power system actually work on site requires far more calculation. We model every path in the system: the electrical path, the fuel path, the air path, the acoustic path, the mechanical-load path.

What happens when you don’t? Radiators that won’t reject heat. Transfer switches that fail under arc-flash. Silencers that don’t attenuate enough. Acoustic complaints. Stored fuel that degrades because the day-tank loop was wrong. We calculate all of these.

Calculation categories

1. Capacity

Load profile analysis — continuous, peak, transient, motor-starting
Sizing methodology — derating (altitude, temperature, fuel type), redundancy (N, N+1, 2N)
Future expansion — 5- and 10-year projection

Standards: ISO 8528-1, NFPA 110, IEEE 446

2. Electrical

Load flow — steady-state current / voltage distribution
Short circuit (IEC 60909) — symmetrical / asymmetrical fault current, peak
Arc flash (IEEE 1584) — incident energy, PPE category, approach boundaries
Coordination — selectivity, breaker / relay settings, IEEE C37
Harmonics (IEEE 519 / IEC 61000) — THD limits, filter sizing
Motor starting — DOL, soft-start, VFD comparison
Voltage dip & transient — UPS compatibility, ITIC curve

3. Fuel system

Storage sizing — 24h / 72h / 7-day runtime + redundancy
Day tank — gravity feed vs transfer pump, return loop
Polishing — particulate + moisture + biological contamination filtration
Pressure drop — pipe sizing, vent area, dip-tube analysis
Spill containment — bund volume, leak detection (EN 13160)

Standards: EN 12285, KIWA BRL-K903, BS 799, UL 142, API 650, NFPA 30, NFPA 37

4. ★ HVAC / Ventilation / Cooling — the most commonly-skipped calculation

Most generator rooms fail their first heat-rejection test. The reason is almost always the same: the radiator fan’s static-pressure capacity is below the total pressure drop the airflow has to overcome. Sometimes the opposite — fan capacity far exceeds the rest of the room and the room runs in vacuum; result: the door won’t open, and when it does open it does so with a force above the HSE limit.

The path we calculate:

[Outside air — entry at alternator end]
   ↓ ΔP₁ = inlet louver resistance
[Filter / pre-filter]
   ↓ ΔP₂ = filter pressure drop (with dirty allowance)
[Inside room: alternator → engine traverse]
   ↓ ΔP₃ = ducting + change-of-direction losses
[Radiator core (with fan)]
   ↓ ΔP₄ = heat-exchanger side resistance
[Discharge ducting + exhaust louver — exit at radiator end]
   ↓ ΔP₅ = exit resistance
[Outside]

Σ ΔP < fan static-pressure capacity (× safety factor)

Plus: free-cooling strategy (Europe DC requirement), hot / cold aisle isolation (data centre), make-up air balance.

Standards: ASHRAE 90.1, ASHRAE Handbook, ASHRAE TC 9.9 (mission critical), EN 13779, AMCA 210, NEBB, NFPA 90A

5. ★ Acoustics (intake / room / exhaust + structural)

Acoustic engineering is sound propagation along three separate paths. Many firms add a muffler and stop there. We model all three:

[Genset (source)]
   ├──▶ INTAKE PATH:  room → intake louver → outside
   ├──▶ EXHAUST PATH: engine → silencer → stack → outside
   └──▶ STRUCTURAL PATH: enclosure wall + floor + ceiling (transmission loss)

Insertion loss is calculated for each path separately, then summed logarithmically with:

Distance attenuation (free field / hemi-sphere)
Ground absorption
Atmospheric absorption
Building reflections
Regulatory limit (day / night, distance-weighted)

Standards: ISO 3744, ISO 3746, ISO 8528-10, ISO 9612, BS 4142, EU Outdoor Noise Directive 2000/14, ANSI S12.18, ASHRAE Handbook (Sound & Vibration Control)

6. Seismic

Post-earthquake operability is critical: the grid is down, the generator is the only source. The system must survive and remain functional.

Skid — base-frame deformation, generator attachment
Enclosure — structural + internal equipment attachment
Day tank — anchorage including slosh load
Switchgear seismic qualification — IEEE 693

Standards: ASCE 7, IBC, Eurocode 8 (EN 1998), AISC 360 + 341, IEEE 693, TS 498 / TBDY 2018 (Türkiye)

7. Pressure (air, water, fuel)

Air — radiator + intake / exhaust, compressed-air system (where used)
Water — coolant loop, heat exchanger, jacket-water expansion
Fuel — line pressure, vent area, day-tank vacuum / positive-pressure limits

Standards: Manufacturer limits, ASME B31.1 (power piping), API 14E (oil & gas piping)

Software

We use licensed engineering software plus empirical validation. Every calculation runs through at least two methods.

Discipline	Tools
Electrical	ETAP, DigSilent PowerFactory
Fuel + HVAC	ASHRAE tables + NEC + Excel / Mathcad / custom Python
Acoustics	NEC Acoustix, ASHRAE-method custom calculation sheets
CFD (ventilation simulation) — independent value-add	Custom Python + ANSYS Fluent
Seismic	Custom Python + ANSYS Mechanical
Sizing cross-check	OE sizing tools (multiple vendors compared)

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