Factory Acceptance Testing for Modular AI Data Centers: What to Witness Before Shipment
What a buyer should agree and witness before a modular AI data center ships, including a 200 kW load example and an adaptable acceptance matrix.
By Yuri MilyutinManaging Partner, ModulEdge
Factory acceptance testing (FAT) should show that the equipment and integrated functions within the factory test boundary meet the agreed project requirements. For a modular AI data center, the buyer should agree the load arrangement, operating conditions, failure scenarios, measurements, acceptance criteria and records before the test date. The acceptance package must also identify the work that will be completed after installation.
A useful witness plan follows the future facility’s power and heat paths. It shows where test loads connect, which cooling circuits receive their heat, which site conditions are represented, and which interfaces remain outside the factory boundary.
Before approving the plan, check four items.
- Every requirement being accepted has a measurable result and a responsible signatory.
- The load arrangement represents the electrical and thermal paths under examination.
- Temporary equipment and simulated interfaces are identified in the record.
- Outstanding site tests and deviations have owners and close-out conditions.
The following framework is an illustrative procurement aid for a qualified commissioning team. The project’s approved procedures, manufacturer instructions and engineering authority determine the executable test methods.
Agree the scope before the factory visit
A supplier can test an individual UPS, a cooling skid or an integrated module. Those activities provide different evidence. Ask the supplier to mark the test boundary on the approved single-line diagram, piping diagram and controls architecture.
The test schedule should list installed equipment and software revisions, including temporary replacements. Record whether the outdoor cooling equipment is the unit shipping to site, a temporary heat sink or a simulated interface. Do the same for utility supply, generator connections, building monitoring and the IT load.
Modular assembly creates an opportunity to verify integration before transport. IPS describes factory testing of integrated electrical, mechanical and technical rooms within its commissioning process, followed by installation verification and functional work at the site. The numbering of phases should be agreed in the project documents because different commissioning programmes use different conventions. IPS commissioning framework.
Ask a bidder offering a factory-tested module for the boundary drawing, test programme and list of site completion tests.
Separate shipment release from final facility acceptance
Treat shipment release as a defined project milestone. It may depend on completing selected tests, resolving critical defects and approving a shipping configuration. Final facility acceptance incorporates the installed utility connections, outdoor conditions, site equipment and operational interfaces.
| Milestone | Evidence the buyer should receive | Interfaces to carry forward |
|---|---|---|
| Factory component checks | Identification, configuration and applicable equipment test records | Installation and site connection requirements |
| Factory integrated tests | Measured operation of assembled systems within the documented boundary | Simulated or temporary inputs and exclusions |
| Receipt and installation verification | Condition after transport, reassembly and connection checks | Outstanding energisation and functional prerequisites |
| Site functional and integrated testing | Operation of the installed systems against project requirements | Any deferred seasonal or load-dependent verification |
| Operational handover | Accepted results, deviations, procedures and training records | Agreed operational limits and remaining obligations |
Schneider Electric’s service description for a prefabricated IT module places integral systems testing against the installed design requirements and provides a report of checks and results. The buyer needs the equivalent project-specific record from the selected delivery team. Schneider Electric integral systems test service.
The contract should connect each milestone to the agreed evidence and defect rules. This article’s matrix can help prepare that discussion. The project’s legal and engineering documents govern the acceptance arrangement.
Build the load plan around where heat actually goes
An electrical load bank supplies a controllable electrical demand. The cooling system under examination must receive the intended share of the resulting heat.
For an air-cooled rack with rear-door heat exchange, the relevant thermal path includes rack airflow, the door coil and the water circuit. For direct-to-chip cooling, a defined share of the equipment heat enters a liquid circuit while another share enters the room air. Each path needs an appropriate test arrangement.
Liquid-cooled resistive load banks transfer their heat into a fluid circuit and can support cooling-system commissioning. Avtron describes this operating principle. The connection point still determines how much of the proposed system the test exercises. Avtron liquid-cooled load banks.
For example, a load bank connected to a facility header may exercise the facility pumps and heat rejection but bypass the proposed coolant distribution unit (CDU). A unit connected downstream of the CDU may exercise that interface, subject to the selected load bank’s temperature, flow, pressure and electrical limits. The load bank’s plumbing must reproduce the intended coolant path, with compatible fluid and controls. Mark both cases on the piping diagram.
Resistive load banks also have a defined electrical behaviour. Where a project requires assessment of power factor, harmonics or dynamic load response, the commissioning engineer must select a suitable source of load or simulation. Match the test method to the requirement.
A worked 200 kW test boundary
Consider a hypothetical module whose test specification allocates 200 kW of simulated IT heat as 160 kW to liquid and 40 kW to room air. These are illustrative project inputs. They are independent of any ModulEdge product specification.
Assume the liquid test circuit uses water and the selected operating point permits a 5 K rise across the liquid load. With specific heat approximated as 4.18 kJ/(kg·K):
Mass flow = 160 ÷ (4.18 × 5) = 7.66 kg/s, approximately 459 litres/minute using a water density of 1 kg/litre.
This is a thermal balance for the specified load. The engineer must check the complete pressure drop, actual fluid properties, available pump head and equipment operating envelope. The commissioning plan must define where each sensor is located.
| Test input | Illustrative allocation | What to record |
|---|---|---|
| Liquid-side simulated IT heat | 160 kW | Electrical input, fluid flow, supply/return temperatures and pressure at identified points |
| Air-side simulated IT heat | 40 kW | Input load, representative air distribution and measured room/rack inlet conditions |
| Simulated IT total | 200 kW | Consistent metering boundary and evidence both branches operated together |
| Cooling and electrical auxiliaries | Separate measured loads | Their power and where their heat enters the balance |
If the factory can provide only a 100 kW liquid test while supplying the full 40 kW air load, the record should state exactly that operating point. The plan needs a separate disposition for the untested liquid duty. An alternative source of evidence may be acceptable if the responsible parties agree its scope before acceptance.
A test using 200 kW of air-heating load exercises a different thermal allocation from this example. To evaluate the planned 160/40 split, place the heat in the assigned paths and trend the coupled system. Suitable equipment can coordinate air-cooled and liquid-cooled loads, but its specific configuration and control limits must be checked. Aggreko describes a combined load-bank control arrangement.
An illustrative factory witness matrix
The buyer and commissioning authority can adapt the following rows. Each approved test script needs a unique ID, the drawing and software revisions, readiness checks, expected result, acceptance limits, abort conditions and named authority to proceed.
| Test objective | Condition to define in the approved script | Evidence to retain | Acceptance basis |
|---|---|---|---|
| Confirm the delivered configuration | Installed equipment, firmware, settings and drawing revision | Serial/configuration register, signed inspection record | Approved equipment schedule and design |
| Verify electrical distribution | Agreed operating/load points and instrumentation | Metered inputs/outputs, settings and relevant inspection/test reports | Approved electrical design and equipment limits |
| Verify cooling at the selected point | Specified heat allocation, water conditions and air conditions | Synchronized power, flow, temperature and pressure trends | Approved thermal design and equipment-manufacturer limits |
| Check a specified loss of supply | Engineer-approved method, load and recovery sequence | Event log, measured response and operator indications | Project continuity requirements |
| Check the required cooling failure case | Approved simulation or controlled test within safety limits | Remaining capacity, temperatures, alarms and actions | Agreed normal/degraded operating requirement |
| Verify controls and monitoring | Defined signals, states, network interfaces and destinations | Point-to-point results, timestamps and command/state confirmation | Approved cause-and-effect and points schedule |
| Verify alarm handling | Approved alarm inputs and acknowledgement/reset sequence | Alarm/event records and displayed operating guidance | Agreed alarm philosophy |
| Check recovery and return to service | Approved restoration sequence and permitted loading | Stable-state trends and remaining defects | Approved recovery procedure |
This matrix leaves numerical limits to the approved design. The contractual test duration should be sufficient for the behaviour being demonstrated, including relevant control cycles and stabilization. Assign time to the required electrical and thermal operating states and recovery sequences.
Demonstrate the complete sequence
Review each script as a sequence from initial conditions through return to service. A supply interruption may change pump operation, controls power, alarms and cooling availability as well as the electrical path to the racks.
For an illustrative cooling-failure case, the design team should define the intended initial load, the failure being represented, the allowable temperature response, automatic actions and operator instructions. The approved method may use simulation where a live fault would exceed the safe test envelope. Record which response was physically demonstrated and which was demonstrated through simulation.
Only authorized personnel should perform energized switching, protective-device tests or controlled fault scenarios under the approved safety arrangements. Readiness checks and abort authority belong in the script. The buyer’s witness should be able to follow the evidence without improvising the procedure.
When the module’s cooling depends on site equipment absent from the factory, include a site completion test that exercises that real interface. Temporary plant conditions and any correction method need engineering approval and a clear evidentiary limit.
Retain trends that allow a second engineer to assess the result
A useful report lets someone reconstruct what happened.
Specify measurement locations, instrument identification and calibration status, units, sampling interval and synchronization of relevant systems. The required time resolution depends on the phenomenon being assessed. Slow thermal trends and rapid transfer events may require different recording methods.
Retain the raw data and the annotated test record. Note changes in load, commands, alarms, manual actions and any equipment substitutions. If an excursion occurred, explain its cause, disposition and retest reference. A final summary with only “pass” entries leaves the operating conditions difficult to verify.
The container data-center specification guide covers the broader interfaces to define before fabrication. Use its project schedule together with this witness record so the accepted test can be traced to the actual equipment ordered.
Close defects against the accepted configuration
Agree defect categories, authority to accept a deviation, required retests and the shipment hold points before testing begins. Distinguish an observation from an accepted design change.
For a corrected sensor fault, a local retest may be sufficient if the approved process establishes that its effects are contained. A change to controls logic or electrical settings may require broader regression testing. The responsible engineer should define and sign that scope.
Retain the following in the close-out package.
- Approved test procedures and completed records.
- As-tested configuration and the changes made after testing.
- Raw trends, equipment reports and calibration records.
- Open-item register with owners and release/closure conditions.
- Packing, transport, reconnection and inspection requirements.
- Site commissioning plan and required operating documentation.
After transport and reassembly, confirm that the accepted configuration has been restored and verify the connections disturbed by shipping. Include actual site supply, cooling and monitoring interfaces in the completion programme.
Ask for evidence matched to your project
A buyer preparing a modular AI facility should send the rack schedule, electrical and thermal interfaces, required operating outcomes and intended site conditions to the delivery team. Ask the team to mark which tests will take place at the factory and which need the completed site.
Our manufacturer, provider and integrator guide addresses allocation of design and delivery responsibilities. The same allocation should name the party responsible for each test, each defect and each final acceptance record.
For a ModulEdge discussion, include the proposed equipment and any witness, reporting or site-acceptance requirements in the enquiry. The project proposal can then establish the applicable supply and test scope.
Frequently asked questions
What should a modular data-center FAT report contain?
Include the test boundary, actual configuration and conditions, procedures, results, raw records, deviations and sign-offs. Identify site work required to complete acceptance.
Can a load bank test replace testing with the actual AI servers?
It can demonstrate defined electrical and thermal behaviours. Server-specific interfaces, controls, workloads and operating behaviour still need the appropriate verification plan. State the load bank’s representational limits.
How long should factory acceptance testing take?
Set the duration from the project’s required demonstrations, load points, stabilization and recovery sequences, and the supplier’s approved procedure. Agree retest time and witness availability in the programme.
Does factory acceptance establish site readiness?
Site readiness requires its own evidence for the installed civil, utility, cooling, network and operational interfaces. Connect factory release and site acceptance through the agreed completion schedule.
