Factory Acceptance Testing

A wiring error found on a works floor costs an hour. The same error found during site commissioning costs an access slot, a lifting plan and often a programme week. Factory acceptance testing exists to shift discovery left — proving equipment against the specification and the approved drawings while the manufacturer still has the panel open and its engineers standing next to it.

We witness and, where scope allows, actively test: mechanical operation and interlocking, primary and secondary wiring verification against schematics, protection relay configuration and functional trip proving, VT/CT circuit checks, LV auxiliary and DC systems, labelling, IP integrity and documentation completeness.

Manufacturers test to their own routine schedules, which prove the product — not necessarily the project. Our review compares the build against the purchase specification, the approved single line diagram and the settings schedule, catching the deviations that routine tests are not designed to find: wrong CT ratio fitted, missing spare cores, interlock philosophy that does not match the site switching plan, relay firmware that lacks a required function.

Because the same engineers often commission the equipment on site, FAT records become the baseline rather than a filed document. Settings already proven at works are re-verified rather than rediscovered, and the site test programme is shortened accordingly.