A control panel can operate correctly in the builder's shop and still encounter problems after it reaches the plant. Field wiring may differ from the drawings. A network connection may not behave as expected. A site device, utility, or operating sequence may introduce a condition that the shop test could not reproduce.
That is why many industrial projects use two separate acceptance stages.
A factory acceptance test (FAT) checks the panel or automation system against an agreed specification before shipment, typically at the builder's or vendor's facility. A site acceptance test (SAT) checks the installed system and its site interfaces at the final location. The stages are related, but they answer different questions.
No universal checklist fits every panel. Build the procedure from the contract, approved drawings and specifications, applicable codes and standards, equipment documents, risk assessment, and test procedure. Those sources define what the team will inspect, demonstrate, record, and approve.
FAT vs. SAT at a glance
| Question | Factory acceptance test (FAT) | Site acceptance test (SAT) |
|---|---|---|
| Where does it happen? | Typically at the panel builder's, manufacturer's, or integrator's facility before shipment | At the final installation site after the equipment is installed and connected |
| When does it happen? | After the shop build is ready for the written test scope and before shipment | After installation and connection to the relevant site systems |
| What is the main purpose? | Demonstrate that the supplied panel or system meets the agreed shop-test scope and applicable specification | Demonstrate that the installed system and agreed site interfaces meet the applicable specification |
| Who may participate? | Representatives of the panel builder, equipment vendor, buyer, owner, OEM, or engineering team, as defined by the test plan | Representatives of the owner, installer, panel builder, equipment vendor, engineering team, or commissioning team, as defined by the test plan |
| What defines the test? | Specification, drawings, bill of materials, I/O list, software revisions, and approved procedure | FAT closeout, approved drawings, equipment documentation, site requirements, and approved procedure |
| What can it evaluate? | Documentation, build alignment, controls, software, simulated I/O, alarms, interlocks, communications, and ordered functions, as applicable | Installation, field wiring, connected devices, site communications, utilities, controls, alarms, interlocks, and agreed operating sequences, as applicable |
| What can it not fully prove? | Actual site wiring, field devices, utilities, network conditions, environment, or process performance | Every operating condition, long-term reliability, or requirements outside the approved SAT scope |
| Typical output | Test record, deviations or punch list, corrective actions, and shipment-release decision | Site test record, open items, retest evidence, documentation turnover, and acceptance decision |
The IEC 62381:2024 standard addresses FAT, SAT, and site integration testing for automation systems in the process industry. It describes these tests as demonstrations against the applicable specification and calls for owners, buyers, and vendors to agree on scope and responsibilities. Its checklists are starting points for project-specific plans; each project sets the final procedure.
ABB's RELION 630 series commissioning manual provides a product-specific example from protection-relay commissioning. It describes FAT as verification of the device and configuration against requirements, while SAT verifies that the installed device is correctly set and connected to the power system.
What is a factory acceptance test?
FAT is the controlled opportunity to find problems before the panel leaves the shop. The team compares the built equipment and available functions with the approved requirements and records what passed, what did not, and what still cannot be tested.
Depending on the project, FAT may involve the panel builder, equipment vendor, customer representatives, engineer of record, OEM, or another agreed witness. Attendance and sign-off authority should be defined before the test begins. Remote witnessing may also be possible. When it is part of the written procedure, define the test setup, evidence, communications, and approval method.
The word factory does not mean every real site condition can be reproduced. A shop may simulate field signals and loads, but it usually cannot duplicate the plant's complete electrical distribution, network, connected machinery, environmental conditions, or process.
What FAT can accomplish
Within its written scope, FAT can:
- Compare the panel with approved drawings, specifications, and the bill of materials.
- Review labels, component identity, workmanship, and documentation.
- Demonstrate included controls, indicators, HMI screens, PLC logic, communications, alarms, permissives, and interlocks.
- Exercise simulated I/O and operating sequences when the test setup supports them.
- Record deviations while corrective work is still at the shop.
- Establish which checks are complete and which must wait for the site.
For example, ABB's remote FAT material for drive systems lists visual inspection, review of routine-test documentation, panel operation, drive startup, a no-load run, protections, alarms, and optional ordered functions. Those examples come from a specific manufacturer and product context. Each control-panel project still needs its own checklist.
What is a site acceptance test?
SAT begins after the equipment reaches its intended location and the installation is ready for the agreed checks. The focus shifts from the panel as a shop-built assembly to the panel as part of the plant.
This is where the team can evaluate conditions that FAT could not fully represent: field wiring, connected sensors and actuators, plant networks, available utilities, site power, equipment interfaces, and selected operating sequences. The SAT procedure should also identify prerequisites. A check should not begin simply because the panel is physically present.
After transport and installation, the team may reconfirm selected factory checks. SAT should focus on installation quality and site interfaces within the approved scope. For Riverside projects, align the SAT plan with the documented field-service scope.
What SAT can accomplish
At the installed site, SAT can:
- Confirm that the delivered panel, drawings, software revisions, and FAT closeout records agree.
- Inspect the installed condition against approved drawings and manufacturer instructions.
- Verify the field wiring, I/O, devices, communications, controls, alarms, permissives, and interlocks covered by the SAT procedure.
- Demonstrate site-specific interfaces and operating sequences under approved conditions.
- Record installation or integration issues separately from unresolved factory items.
- Complete agreed training, documentation turnover, punch-list tracking, and acceptance records.
Why FAT does not eliminate SAT
FAT can catch a mislabeled device, incorrect drawing revision, programming issue, or unsuccessful simulated sequence before shipping. Correcting those items at the shop may be faster and less disruptive than discovering them during installation.
But a successful FAT cannot confirm that every cable was landed correctly at the plant or that every external device communicates with the panel. It cannot prove the condition of site power, grounding and bonding, utilities, networks, or equipment that was not part of the factory test setup.
SAT closes that gap by checking the installed system and agreed field interfaces. It may also reveal transportation damage, installation changes, mismatched revisions, or site conditions that were not available during FAT.
Treat FAT and SAT as separate acceptance gates. Keep commissioning, required inspections, safety validation, and out-of-scope tests as distinct project obligations.
Define acceptance before the test date
Write the FAT and SAT plans while the project still has time to resolve unclear requirements. For Riverside projects, include this scope in the design and specification work. Waiting until the panel is complete can turn the test into a debate over expectations instead of a demonstration against stated criteria.
Before build release, the parties should identify:
- The approved specification, drawings, I/O list, bill of materials, and software or firmware revisions.
- Which functions will be inspected, simulated, demonstrated, or deferred.
- The test environment and any equipment, loads, signals, utilities, or network connections that will and will not be available.
- Measurable acceptance criteria and the source of each criterion.
- Required records, screenshots, test forms, software backups, and sign-offs.
- Who prepares, performs, witnesses, accepts, and documents each stage.
- Hold points, notice periods, remote-witness arrangements, and scheduling responsibilities.
- How deviations, approved exceptions, corrective actions, and retests will be handled.
Replace “runs correctly” with a measurable result and the evidence needed to demonstrate it.
Industrial control panel testing and qualified persons
FAT and SAT planning is not a substitute for an electrical-safety program or task-specific procedure. Some checks can involve electrical, mechanical, stored-energy, process, or startup hazards.
For U.S. general-industry work where it applies, OSHA 29 CFR 1910.333 generally requires exposed live parts to be de-energized before work unless the employer establishes an applicable exception. De-energized fixed equipment that has not been locked or tagged under the rule's procedure must be treated as energized. The rule assigns verification of de-energization and work on exposed energized parts to qualified persons using appropriate work practices.
This article does not define who is qualified for a specific task. The employer, hazards, applicable requirements, equipment instructions, and approved safety procedures govern how the work is prepared and performed.
FAT planning checklist for a control-panel project
The following list is a planning framework. The approved FAT procedure should include only the checks that apply to the supplied equipment, specification, test environment, and agreed responsibilities.
1. Document readiness
Confirm that the test team has the correct revision of the drawings, specification, bill of materials, I/O list, control narrative, software files, manuals, and FAT procedure. Identify documents that will remain preliminary until closeout.
2. Build and visual review
Compare the available panel details with the approved documents. The project procedure may address component identity, labels, enclosure features, operator devices, workmanship, accessibility, and documented deviations.
3. Controls and software
List the HMI screens, PLC logic, drive functions, operating modes, setpoints, communications, alarms, permissives, and interlocks that the factory setup can demonstrate. Record the software revision. For unavailable field signals, state the simulation method.
4. Sequences and interfaces
List the sequences and interfaces included in the test. State which external devices or networks the test equipment or simulation represents. Mark those items for confirmation with the final site hardware.
5. Results and shipment release
Record results against the agreed criteria. Assign each deviation to an owner. State whether it requires correction and retest before shipment, completion at the site, or a written exception permitted by the contract and applicable requirements.
SAT planning checklist for a control-panel project
Use this SAT checklist as a planning framework. Build the final procedure around the installed equipment, site prerequisites, safety controls, and written project requirements.
1. FAT closeout and delivered condition
Confirm the panel identity, delivered documentation, software revision, FAT record, open items, approved changes, and any conditions attached to shipment.
2. Installation and site interfaces
Define the required review of the installation, site power, grounding and bonding, field wiring, connected devices, networks, utilities, environmental conditions, and other interfaces. Compare each applicable item with the approved drawings, equipment documentation, and project requirements.
3. Field I/O and communications
Identify the agreed method for confirming relevant field signals, devices, network paths, and data exchange. Separate communication checks from process-performance claims that require additional commissioning or production conditions.
4. Controls and operating sequences
Specify which controls, modes, alarms, permissives, interlocks, and operating sequences can be demonstrated safely at the site. Note the conditions, equipment state, and personnel required before each check.
5. Closeout and acceptance
Track remaining items, corrective work, retest evidence, software backups, final drawings, manuals, training, and sign-off. Base acceptance on the written SAT scope. Track unrelated project obligations separately.
What happens when a test does not meet the criteria?
A failed or incomplete check requires a documented disposition.
The test record should identify the criterion, observed result, evidence, responsible party, corrective action, and retest requirement. The project procedure should also distinguish among:
- A defect whose applicable criterion requires correction before shipment or energization.
- An item that cannot be tested until the site is ready.
- A document or drawing that needs revision.
- A change requested outside the original scope.
- A written exception the authorized parties may accept only where the contract and applicable requirements permit one.
Record each open item's owner, next test stage, and retest requirement. This keeps site prerequisites separate from factory failures and carries unresolved factory defects into the installation record.
Include FAT and SAT expectations in the panel specification
Riverside Drives designs and builds custom control panels. Its design services include requirements collaboration, AutoCAD engineering, programming, and testing of VFDs and panels in the shop or field. Riverside states that it uses test stands to approximate field conditions. Its field services include installation, certified ABB drive startup, automation troubleshooting, and VFD repair.
If the control-panel specifications require a formal FAT or SAT, identify the test protocol, witness points, simulations, records, and signed acceptance documents in the request for quote. Ask Riverside which items are available and included in its proposed scope. The parties can then confirm what the test setup can reproduce, which checks must wait for the site, and who owns each prerequisite.
Discuss your control-panel specifications and acceptance requirements with Riverside Drives before the build is released.
Frequently asked questions
What is the difference between FAT and SAT?
FAT checks the panel or automation system against an agreed specification before shipment, typically at the builder's or vendor's facility. SAT checks the installed system and agreed site interfaces at the final location. The written project procedure determines the exact scope of each.
Is a factory acceptance test required for every control panel?
Not necessarily. Formal FAT requirements depend on the contract, specification, equipment, process risks, applicable requirements, and customer expectations. If FAT is important to acceptance, include it explicitly in the project documents.
Can SAT replace FAT?
The stages address different conditions. SAT can verify site installation and interfaces that a factory test cannot reproduce, but discovering shop-build or programming issues only after installation may add delay. The project team should decide which stages are needed and document that decision.
Who should attend or witness FAT and SAT?
There is no universal attendee list. The test plan should identify the people authorized to prepare, perform, witness, document, and accept the test. Depending on the project, that may include representatives of the buyer, owner, panel builder, equipment vendor, OEM, engineering team, installer, or commissioning team.
What happens when a panel does not meet an acceptance criterion?
Document the result as a deviation or open item under the test procedure. The authorized parties can assign correction and retest or defer the check to a defined later stage. They may approve a written exception or scope change only where the contract and applicable requirements permit it.