Data Centre Generator Commissioning: FAT to IST Checklist

Commissioning Scope And Success Criteria For Data Centres

Generator commissioning underpins data centre resilience. The objectives are clear: prove safety, statutory compliance and stable performance against the real site load profile. The programme typically spans Factory Acceptance Test (FAT), delivery checks, Site Acceptance Test (SAT), load bank proofs and Integrated Systems Testing (IST) including black‑building.

Acceptance criteria: reliable starting, ISO 8528 transient performance, clean power quality, UPS compatibility, controls integration, and complete documentation.
N+1 schemes: demonstrate seamless resilience across credible faults (single set loss, breaker failure to close, governor/AVR fault, comms loss, sensor failure).

PowerTech Generators is brand‑independent across Cummins, Perkins, FG Wilson, Baudouin and others. See ISO 8528 performance classes for thresholds and G99/G98 witness testing guidance when any grid interface is in scope.

Pre‑Commissioning Design Readiness And Risk Planning

Validate the load model: normal and peak kW/kVAr, step sizes, UPS recharge, motor inrush, contingency loads.
Confirm UPS topology (double conversion/eco), VFD harmonic content and starting methods (DOL/soft/VSD).
Right‑size engine/alternator and control windows early using our kVA calculator.
Review the single‑line: protection grading, short‑circuit levels, earthing arrangement and neutral switching (3‑ or 4‑pole).
Lock down RAMS, permit‑to‑work, risk register and a commissioning programme with dependencies and hold points.
Plan spares/consumables and consider temporary generator hire to maintain resilience during changeover or switchboard works.

Factory Acceptance Test (FAT) Checklist And Witness Plan

Configuration checks: nameplate kVA, duty rating (Prime/Standby/Continuous), alternator class, wiring, controller firmware.
Controls and protection: governor stability, AVR configuration, alarms and protective shutdowns.
Interfaces: remote I/O mapping, communications (CAN/Modbus), logic interlocks and failsafes.
Performance: 0–50–100% step loads, transient recovery, cold/hot starts, endurance run where feasible.
Evidence pack: calibration sheets, serials, test certificates and a signed FAT matrix to de‑risk SAT.

Delivery, Installation And SAT Preparation

Site readiness: access and cranage, plinths/baseframes, vibration mounts, acoustics, intake/discharge airflow, exhaust routing within backpressure limits.
Fuel system: storage capacity, polishing/filtration, fire strategy and spill containment to UK guidance.
Electrical works: inspect cables and terminations, torque logs, earthing and bonding, neutral switching scheme and labelling.
Pre‑energisation: complete ITP/ITC, insulation and rotation checks, and a SAT briefing so all parties understand sequence, LOTO and safety controls.

This image was generated with AI and may not always represent the product or service exactly.

Site Acceptance Test (SAT) Procedure

Pre‑start: inspect fluids, heaters and chargers; prove cold start and hot start.
Safety systems: test all alarms/shutdowns (low oil pressure, high coolant temperature, overspeed, emergency stop).
Ancillaries: verify fuel transfer interlocks, ventilation fans and dampers.
ATS operation: exercise open and closed transition as designed, including bypass isolation and controlled retransfer timing.
Protection and telemetry: validate protection settings, metering accuracy and BMS/SCADA points; confirm remote monitoring paths and alarm escalation for 24/7 response.

Load Bank Proofs And Endurance Testing

Resistive/reactive proofs to verify voltage/frequency stability, transient recovery and alternator thermal limits.
Run a 2–4 hour heat soak at operating load.
Where the alternator rating permits, demonstrate a controlled 110% short overload.
Prove a black start from cold with no mains present.
Use progressive step loads that mirror UPS recharge and motor starting behaviour to avoid nuisance trips and poor power quality. See our guide to generator load testing.

Controls Integration, Paralleling And UPS Interface

Paralleling checks: synchronising conditions, bus acceptance, breaker interlocks and load sharing.
Verify kW/kVAr sharing accuracy, droop/isochronous modes and isochronous load sharing where applicable. See best practice for synchronising multiple generators for N+1 resilience.
Fault handling: prove out‑of‑sync close rejection, breaker fail, set loss and comms loss responses.
UPS interface: define acceptable voltage/frequency windows, THDv limits, ride‑through and recharge controls; set ramp rates for soft loading/unloading and peak lopping if required. Prevent nuisance transfers using our UPS–generator integration and harmonics guidance.

Black‑Building And Integrated Systems Testing (IST)

Run full outage simulations to validate the end‑to‑end sequence.
Time and record: DNO loss to ATS transfer, engine crank to on‑load, UPS ride‑through, and cooling/HVAC recovery.
Prove return‑to‑mains logic and safe retransfer criteria under load.
Test EPO, fire alarm inputs, damper and fuel shut‑off interactions, and life‑safety priorities.
Capture timings, waveforms and screenshots; log defects and retest to closure before acceptance.

This image was generated with AI and may not always represent the product or service exactly.

Power Quality And Harmonics Sign‑Off

Measure THDv, THDi, frequency stability and neutral currents with representative UPS/VFD‑heavy loads.
Confirm AVR mode (line or PMG), alternator subtransient reactance suitability and the neutral earthing method.
Apply corrections as needed: adjust governor/AVR setpoints, add line reactors or filters, or refine UPS acceptance windows to stabilise non‑linear loads.

Documentation, Training And Compliance Handover

Handover pack: O&M manuals, datasheets, as‑built drawings, protection settings, cause/effect matrices, FAT/SAT/IST records, calibration certificates and warranties.
Spares: critical spares and consumables list aligned to the maintenance strategy.
Training: start/stop procedures, alarm response, first‑line checks and fuel contamination risks.
Compliance: G99/G98 where applicable, BS 7671 test results, noise data and emissions statements for audit and insurer needs.

Service, Maintenance And Lifecycle Resilience

Adopt a PPM plan including oil analysis, coolant chemistry, battery testing and periodic load banking to prevent wet‑stacking.
Enable remote monitoring with 24/7 call‑out SLAs for rapid fault resolution.
Re‑validate after firmware or setpoint changes, especially at UPS interfaces.
Plan decommissioning and export support at end of life with environmental controls and logistics.

Commercial Options And Programme Delivery

Choose from industrial generators for sale (new and used generators UK) with clear lead times, or use generator hire to bridge outages or construction phases.
We deliver ATS panels and turnkey works to compress programme risk and maintain uptime.
Finance options, trade‑in and rapid deployment align budget and timescales. Single point of responsibility from factory build through installation, commissioning and handover.

Why Choose PowerTech Generators For Data Centre Commissioning

We are an independent, engineering‑led partner with multi‑brand expertise (Cummins, Perkins, FG Wilson, Baudouin and more). Our compliance‑first process covers design review, FAT, SAT, load bank testing and IST, with 24/7 support.

PowerTech Generators has proven delivery across data centres, healthcare, manufacturing and utilities. Book a site survey and commissioning programme today via Contact.

FAQs

How long does generator commissioning take on a data centre?

Typical programmes run 1–3 weeks per plant, driven by system complexity, paralleling and IST scope. Strong design readiness and a clear test matrix shorten site time.

Do I need G99/G98 approval for standby generators?

If you parallel with the grid, G99 applies and may require DNO witness testing. Island‑only standby usually sits outside G99 but still needs a safe ATS and correct protection settings.

What load bank size should I use for proofs?

Match the generator rating and planned step sizes, allowing for reactive capability. Include a 2–4 hour heat soak at operating load and only attempt controlled overloads if the alternator permits.

Can you commission any OEM generator and controller?

Yes. We are brand‑independent across major engines, alternators and control platforms, and we tune governors/AVRs and integrate with third‑party switchgear and UPS.

What documents will I receive at handover?

O&M manuals, as‑builts, protection settings, cause/effect matrices, FAT/SAT/IST evidence, calibration certificates, warranties and a spares list.

How often should I repeat load bank testing?

Annually is best practice for standby sets, or after significant electrical changes. This verifies performance, prevents wet‑stacking and confirms UPS compatibility.

Can commissioning be phased to maintain uptime?

Yes. We plan phased works, temporary hire sets and night shifts to protect live services, with clear RAMS and stakeholder briefings throughout.