Factory Inspection: Six Mandatory Categories
Factory inspections (factory tests/FAT) for complete electrical assemblies are conducted in accordance with relevant standards (GB/T, IEC). There are six mandatory categories of inspection: visual and structural checks, insulation tests, withstand voltage tests, protection function tests, temperature rise tests (sample-based), and mechanical operation tests. Industry experts note that the specific inspection items depend on the product type and its corresponding standard list.
Factory inspection serves as the final quality gate before shipment;
inspection records are delivered with the goods, allowing for verification during acceptance.
Six Categories of Factory Inspection Items
- Visual and structural checks: Enclosure dimensions, protection rating (IP code), nameplates/markings, and assembly integrity;
- Insulation tests: Insulation resistance testing (main circuit to ground and phase-to-phase) to verify insulation performance;
- Withstand voltage tests: Power-frequency withstand voltage (based on voltage rating) to verify insulation strength;
- Protection function tests: Circuit breaker opening/closing and verification of protection actions (overcurrent/short-circuit);
- Temperature rise tests (sample/type test): High-current temperature rise verification to ensure adequate heat dissipation;
- Mechanical operation tests: Verification of operating mechanism cycles (opening/closing) and “five-prevention” interlocking functions.
Execution of Factory Inspection
Factory inspections are carried out by the manufacturer’s quality control department in accordance with inspection procedures.
A factory inspection report (FAT) is issued, and recorded data (insulation values, withstand voltage values, operation counts) are delivered alongside the equipment. Factory tests for high-voltage equipment (per GB/T 3906) cover main circuit insulation, withstand voltage, and mechanical operation, while type tests involve a separate, comprehensive set of procedures.
Key Points for Acceptance Review
First, cross-reference reports: Compare the goods upon arrival against the factory inspection report and verify the data.
Second, conduct spot checks: The buyer should perform spot checks on critical equipment (e.g., insulation and withstand voltage tests) to verify consistency.
Third, ensure report completeness: Check that all inspection items and data are present;
require supplementary testing for any missing items.
Fourth, witness testing: For bulk purchases, require witnessing of factory acceptance tests (FAT).
Pitfalls to Avoid
First, “missing inspection reports”: Equipment lacking FAT reports is of questionable quality.
Second, “report falsification”: Falsified inspection data can be exposed through spot checks.
Third, “missing test items”: Missing withstand voltage or protection tests require supplementary testing during acceptance.
Trends and Reminders
Factory inspections are moving toward “digitalization”: inspection data is becoming electronic, FAT reports are being uploaded to the cloud, and verification can be done via QR code scanning during acceptance.
Buyers are advised to follow the “report-with-goods, data cross-reference, and spot-check verification” approach.
Factory inspection acts as the guardian of quality—comprehensive testing ensures confidence before the product leaves the factory.
