Routine Tests and FAT: What Is the Difference?
Both activities verify switchgear quality, but they serve different purposes, participants and acceptance decisions.
Routine testing and Factory Acceptance Testing are often discussed together, which can make their boundaries unclear. A routine test is the manufacturer’s defined verification that each manufactured assembly meets the applicable product and design requirements. A FAT is a project-focused acceptance activity in which the agreed functions, interfaces and documentation are demonstrated—often in front of the customer or an appointed representative.
Routine testing verifies the manufactured product
Routine tests are performed on each completed unit or assembly as required by the applicable product standard and the manufacturer’s quality process. The exact test list depends on the equipment, but typically includes construction checks, mechanical operation, wiring verification, functional checks and dielectric or insulation-related verification.
The routine-test procedure should state the test method, required equipment, test values, duration, acceptance criteria, precautions and record format. The result must be objective: pass, fail or an identified nonconformity requiring correction and retest.
FAT verifies the agreed project solution
A FAT usually combines review, inspection and selected testing. It may repeat or witness parts of the routine test, but its main value is demonstrating that the supplied panel performs the customer-specific functions defined in the approved drawings, specifications and operating philosophy.
| Aspect | Routine test | FAT |
|---|---|---|
| Primary purpose | Verify every manufactured assembly | Demonstrate project compliance and functionality |
| Basis | Product standard and manufacturer procedure | Approved project documents and FAT protocol |
| Participants | Normally manufacturer quality/testing personnel | Manufacturer plus customer or witness |
| Output | Routine test report | Signed FAT protocol, punch list and evidence |
A practical FAT structure
- Document and drawing review
- Visual and mechanical inspection
- Nameplate, device and wiring checks
- Auxiliary supply and indication checks
- Protection, control and interlock demonstrations
- Local/remote and communication interfaces where included
- Review of routine-test results and project certificates
- Recording of punch items, responsibilities and closure evidence
Acceptance criteria must be defined before the test
Statements such as “operation checked” are too vague. A useful protocol describes the initial condition, action, expected result and evidence. If simulation equipment or temporary test links are used, the protocol should explain how they are controlled and removed.
Safety and equipment protection
Before applying test voltage or operating coils, isolate equipment that cannot withstand the test condition. Sensitive electronics, surge-protection devices, instrument circuits and external interfaces may need disconnection or an alternative verification method. Test boundaries and restoration checks should be documented.
Close the loop
A successful FAT is not simply a signed day at the factory. All punch items should have a classification, responsible party, due date and closure evidence. Revised drawings and software must match the tested condition. Only then does the FAT provide a reliable baseline for delivery and site commissioning.