A transformer weighs tonnes and travels far. A defect discovered after delivery costs a fortune. That is the whole point of factory testing, and of having it verified by a third party.
The FAT (Factory Acceptance Test) is the acceptance of the transformer at the manufacturer's, before shipment. Against an agreed protocol, it verifies that the unit conforms to the order and to the standards. The point is simple: fixing a problem at the factory costs infinitely less than discovering it once the unit is installed on site.
One level up: a witness test has the tests attended by an independent third party, a recognised body such as KEMA, TÜV or DNV, or a client representative. The third party observes that the tests are genuinely carried out, by the book, and that the results comply. It is a precious guarantee of independence when buying from a supplier you do not yet know.
Among the typical checks: the turns ratio and the vector group, winding resistance, no-load and load losses (essential with regard to Tier 2), dielectric withstand (insulation), temperature rise, and tightness for an oil-immersed unit. The measured values are recorded in a test report.
Buying a transformer built far away raises a genuine question of trust. Tests, and above all witness tests, give it a concrete answer: quality is verified and documented before departure, not discovered on arrival. It is one of the pillars of our manufacturer model: we follow production on site and organise witness tests on request. See how we work and EU compliance.
General overview; the precise test list and the acceptance protocol are defined in the specification.
Routine tests are performed on every transformer produced (they validate the unit). Type tests are performed on a representative unit of a design (they validate the design). Both fall under IEC 60076.
A test attended by an independent third party (KEMA, TUV, DNV and others) or a client representative, who observes that the tests are genuinely and correctly carried out and that the results comply. It brings independent assurance before shipment.
No, but they are strongly recommended when buying from a distant or new supplier. We can organise them on request; the option appears in the configurator.
Yes. The measured values (turns ratio, losses, dielectric withstand and so on) are recorded in a test report that travels with the unit.