Factory Acceptance Testing (FAT) Checklist
A Practical FAT Checklist for Control Panels and Automation Systems
Factory Acceptance Testing provides an opportunity to identify problems with industrial control panels and automation systems before equipment reaches site.
A well-planned FAT should do more than demonstrate that the panel powers up.
It should verify that the manufactured control panel corresponds with the approved design, electrical circuits operate as intended, PLC inputs and outputs behave correctly, automation sequences have been tested where practical, and the required documentation is available.
The exact FAT will depend on the equipment, project specification and agreed scope.
However, the following checklist provides a practical starting point for engineers, project managers and customers preparing to witness or carry out an industrial automation FAT.
Documentation Review Before FAT
Before testing begins, confirm that the appropriate project documentation is available and reflects the system being tested.
Check:
Latest electrical drawings are available.
Drawing revisions are clearly identified.
Approved control panel design is available.
Component schedules are available.
I/O list is available.
PLC hardware configuration is documented.
Network architecture is available where applicable.
HMI or SCADA requirements are available.
Relevant functional or control descriptions are available.
Previous design changes have been incorporated.
FAT procedure and acceptance criteria have been agreed.
One of the most important questions is simple:
Are you testing the system against the latest approved information?
Testing against superseded drawings or an outdated I/O list can create unnecessary confusion during the FAT.
Control Panel Visual Inspection
Before applying power, carry out a visual inspection of the completed panel.
Check:
Enclosure is the correct type and size.
Panel construction matches the approved design.
Components are securely mounted.
Components match the specification.
Component layout is appropriate.
Wiring ducts and trunking are correctly installed.
Internal wiring is orderly.
Required component spacing has been maintained.
Terminals are accessible.
Cable entry arrangements are suitable.
Unused openings are appropriately addressed.
Panel is free from manufacturing debris.
The objective is not simply to judge whether the panel "looks tidy".
The inspection should identify physical issues that could affect installation, operation or future maintenance.
Component and Identification Checks
Components and conductors should be identifiable against the electrical documentation.
Check:
Devices have appropriate identification.
Component labels correspond with drawings.
Terminals are identified.
Conductors are identified where required.
PLC modules correspond with the design.
Protective devices have the correct ratings.
Power supplies are correct.
Contactors and relays match the specification.
Variable Speed Drives match the required application.
Network components are correctly identified.
Safety-related components correspond with the approved design.
Panel identification and required markings are present.
Clear identification becomes particularly valuable once the panel reaches site and engineers who were not involved in its manufacture need to install or maintain it.
Electrical and Power Checks
Electrical checks should be completed according to the applicable design, standards, project requirements and FAT procedure.
Depending on the panel and agreed scope, checks may include:
Incoming supply arrangements.
Protective conductor connections.
Protective bonding.
Circuit protection.
Control voltages.
Power supply outputs.
Transformer outputs where applicable.
Phase arrangements.
Circuit isolation.
Earthing arrangements.
Electrical connections.
Relevant electrical verification or test results.
Do not assume that a circuit is correct simply because the connected device powers up.
The electrical system needs to be assessed against the approved design and applicable verification requirements.
PLC Hardware and I/O Testing
PLC I/O testing verifies that the controller receives and sends the expected signals.
Each relevant input and output should be checked systematically.
Digital inputs
Confirm that simulated or actual field conditions produce the correct PLC input state.
Examples may include:
Push buttons.
Limit switches.
Proximity sensors.
Equipment feedback.
Motor status.
Fault contacts.
Safety-related status signals where applicable.
Digital outputs
Confirm that PLC commands operate the intended output.
Examples may include:
Contactors.
Relays.
Solenoid valves.
Indicator lamps.
Motor commands.
Other actuators.
Where analogue signals are used, check appropriate values across the required range rather than simply confirming that a signal exists.
PLC Software and Sequence Testing
Once the hardware and I/O have been verified, the PLC control logic can be tested against the required machine or process behaviour.
Depending on the system, testing may include:
Start sequence.
Stop sequence.
Automatic operation.
Manual operation.
Equipment interlocks.
Permissives.
Sequence transitions.
Timers.
Setpoints.
Fault conditions.
Reset behaviour.
Recovery following faults.
Where the complete machine or process equipment is not available during FAT, signals may need to be simulated.
The limitations of simulated testing should be understood and any functionality requiring final site testing should be clearly identified for commissioning or SAT.
HMI and SCADA Testing
Operator interfaces should be tested alongside the PLC rather than treated as a purely graphical exercise.
Check:
Navigation operates correctly.
Equipment status is accurate.
Commands operate the intended equipment or simulated function.
Operating modes are displayed correctly.
Setpoints can be entered where permitted.
User permissions operate correctly.
Alarm information is displayed correctly.
Fault information is understandable.
Process values are scaled correctly.
Units are correct.
Trends operate where applicable.
Communication failure behaviour is appropriate.
The HMI should make the automation system easier to operate and diagnose.
A screen that simply displays "FAULT" without helping the operator understand the condition provides limited diagnostic value.
Alarm and Fault Testing
Fault conditions should be deliberately introduced during FAT where practical.
This helps establish whether the control system responds appropriately when something goes wrong.
Test relevant conditions such as:
Sensor failure.
Motor fault.
Drive fault.
Communication failure.
Equipment unavailable.
Process condition outside permitted limits.
Interlock not satisfied.
PLC I/O fault where appropriate.
For each condition, consider:
Detection: Does the PLC identify the problem?
Response: Does the system respond as intended?
Alarm: Is the correct information presented?
Reset: Can the condition be reset appropriately?
Recovery: What happens when the fault is removed?
Testing abnormal conditions is often just as valuable as demonstrating normal operation.
Drives, Motors and Industrial Communications
Where Variable Speed Drives, intelligent motor control or industrial networks form part of the system, these should be included within the FAT where practical.
Drive checks may include:
Drive configuration.
Motor parameters.
Speed reference.
Start and stop commands.
Direction.
PLC communications.
Fault reporting.
Status information.
Network checks may include:
PLC communications.
Remote I/O.
HMI communications.
Drive communications.
Industrial Ethernet devices.
Protocol gateways.
Third-party equipment where available.
Communication failures should also be considered.
The system should behave predictably if a networked device becomes unavailable.
Safety and Interlock Functional Checks
Safety-related functionality requires particular care.
The FAT should verify the agreed functionality within the scope of the test and in accordance with the project's safety design and validation requirements.
Checks may involve:
Emergency stop functions.
Guard interfaces.
Safety relays.
Safety PLC signals.
Safe drive functions.
Reset behaviour.
Restart prevention.
Equipment interlocks.
Defined safe states.
It is important to distinguish between FAT functional testing and formal safety validation.
A successful FAT does not automatically demonstrate that every machinery safety requirement has been satisfied. Required safety validation needs to be carried out according to the machine's risk assessment, safety design and applicable standards.
Final FAT Documentation and Sign-Off
The FAT should finish with a documented record of what was tested and what remains outstanding.
Before accepting the system, confirm:
FAT procedure has been completed.
Test results have been recorded.
Outstanding issues have been documented.
Required corrective actions have owners.
Drawing changes have been identified.
Software changes have been recorded.
PLC backup has been created.
HMI backup has been created.
Drive parameters have been backed up where appropriate.
Required documentation has been supplied.
Items requiring SAT or commissioning have been identified.
Acceptance and sign-off status is clear.
Any deviations discovered during FAT should be controlled rather than disappearing into handwritten notes that never reach the final project documentation.
Where changes are made during testing, the final documentation and software backups should reflect the system actually delivered.
Why a Structured FAT Checklist Matters
The purpose of Factory Acceptance Testing is not to prove that nothing could possibly go wrong once the equipment reaches site.
Some aspects of an automation system can only be fully tested when connected to the actual machinery, instrumentation and production environment.
Instead, FAT provides an opportunity to identify as many problems as practical before installation and commissioning.
Finding an incorrectly wired signal, PLC sequencing problem or HMI error at the panel manufacturer's facility is generally much easier than discovering the same issue after equipment has been installed on a production site.
A structured checklist also creates consistency.
Rather than relying on individual engineers to remember what should be checked, the FAT procedure provides a documented testing framework based on the requirements of the project.
Stratos provides control panel manufacture, PLC programming, Factory Acceptance Testing and automation commissioning, allowing electrical and software functionality to be tested together before systems are delivered to site.
Preparing for a Factory Acceptance Test?
A structured FAT can identify electrical, PLC, HMI and integration problems before equipment reaches site.
Stratos provides industrial control panel manufacture, PLC programming, Factory Acceptance Testing and commissioning, allowing the electrical and automation system to be tested as one integrated solution.
Speak to our engineers about the FAT requirements for your next industrial control panel or automation project.
Frequently Asked Questions
What should be included in a FAT for a control panel?
A control panel FAT may include documentation review, visual inspection, component verification, electrical checks, PLC I/O testing, software sequence testing, HMI testing, alarms, communications and appropriate functional checks. The exact scope should be defined by the project requirements.
Who should attend a Factory Acceptance Test?
FAT may involve representatives from the control panel manufacturer or system integrator alongside the customer's engineering, project or operational teams. Attendance depends on the project and agreed acceptance process.
Is every PLC input and output tested during FAT?
Where practical and within the agreed FAT scope, PLC I/O should be systematically verified. Where field equipment is unavailable, signals may need to be simulated and subsequently confirmed during commissioning or Site Acceptance Testing.
Is FAT the same as SAT?
No. Factory Acceptance Testing takes place before equipment is delivered or installed at its final location. Site Acceptance Testing occurs after installation and can verify the system within its actual operating environment.
Does a successful FAT mean commissioning is unnecessary?
No. FAT can verify a significant amount of the electrical and automation system, but final commissioning remains necessary where equipment needs to be connected to actual motors, instrumentation, machinery, networks and production processes.