Sizing

Right product, right capacity, right specification — chosen with no commercial agenda.

Sizing is where most projects already go wrong. The “rated power” number on a spec sheet is computed under ISO reference conditions (25 °C, 100 m, 30 % humidity, 1.013 bar). Real sites are not that. Most sizing tools give you a clean number but skip the questions that matter: which rating class? What block-load capability? What derating for altitude, temperature, fuel quality? What redundancy topology fits your availability target?

ES4PS does sizing independently — we use no fewer than two methods and compare the results, and we apply derating curves to your actual site conditions.

What we deliver

• Load profile analysis — continuous, peak, transient, motor-starting components broken out separately
• Rating selection — the right ISO 8528 class for your operating profile (ESP / PRP / COP / DCP), not whatever the sales engineer suggested
• Derating report — your actual site conditions applied to manufacturer curves: altitude, ambient temperature, humidity, fuel quality
• Redundancy decision — N, N+1, N+2 or 2N — with the availability calculation that justifies it
• Unit-count optimisation — when 3 × 2 MW parallel is better than 1 × 6 MW, and when it isn’t
• Future-expansion projection — 5 and 10-year load growth modelling

Methodology

We use both licensed manufacturer sizing tools and our own empirical models, and we compare results. Any discrepancy above 5 % gets investigated and explained.

For data-centre and hospital applications we additionally model block-load capability explicitly — ISO 8528-5 transient class (G1 / G2 / G3 / G4), frequency-dip and voltage-dip behaviour, recovery time. Most sizing engagements skip this — and that is why field commissioning surprises happen.

Standards we apply

• ISO 8528-1 — engine-driven AC generator sets: classification, application categories
• ISO 8528-5 — performance classes (G1–G4), transient (block-load) behaviour
• ISO 8528-12 — emergency-power-supply systems (Type 1 / 2 / 3)
• ISO 3046 — reciprocating internal combustion engines — declarations of power
• NFPA 110 — Emergency & Standby Power Systems (Level 1 / 2, Class, Type)
• IEEE 446 (Orange Book) — industrial & commercial emergency + standby power
• IEEE 493 (Gold Book) — reliability analysis (MTBF, availability, redundancy)
• API RP 14F — offshore electrical systems (when applicable)
• NORSOK E-001 — electrical systems (Norwegian offshore)

Tools we use

• ETAP and DigSilent PowerFactory — load flow, transient stability
• OE sizing tools — multiple vendor sizing programs run in parallel for cross-check
• Custom Python models — derating curves, availability calculations, RBD

Typical engagements

• Greenfield sizing for new projects — 2–4 weeks
• Sizing audit of existing or proposed third-party design — 2–3 weeks
• Multi-vendor specification — vendor-neutral spec sheet to let customer drive a real competitive bid — 3–5 weeks
• Rating-class review — when an existing project is failing on uptime letters or warranty disputes due to rating mismatch — 2 weeks

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