What Is FAT vs SAT in Transformer Procurement?

Published 27 Aug 2026Updated 27 Aug 20265 min readBeginnerProcurement

Quick answer — FAT (Factory Acceptance Test) happens at the manufacturer to prove the unit meets the spec before shipment; SAT (Site Acceptance Test) happens after installation to confirm it is set up correctly and ready to energise. FAT covers routine/type tests and inspection; SAT covers commissioning checks, protection, connections and a successful energisation.

Contents

FAT
SAT
Witnessing

What is a FAT and a SAT for a transformer?

FAT

Run at the factory, it verifies the design and the unit against the specification — tests, losses, quality, documentation — and any changes are made before it leaves.

SAT

Run on site after installation, it confirms correct erection, connections, protection settings, auxiliary/cooling operation and that the unit passes the pre-commissioning checks before energisation.

Witnessing

FAT is often witnessed by the customer (or an inspector) for the agreed tests; SAT is witnessed on site and may include a period of supervised energisation.

References & standards

IEC 60076-1
IEEE C57.12.90

Book series Academy

Related manufacturers

Acme Electric (Hubbell) · Central Moloney · CORE Transformers · Daelim Transformer (US) · Delta Star · Eaton

Related components

Protection, monitoring & diagnostics Tank & mechanical

Technical content is prepared from engineering references, standards frameworks, manufacturer documentation and industry sources. Contractual or compliance decisions should refer to current official standards. TransformerPath Technical Editorial.

Travelling for a factory acceptance test (FAT)

Engineers attending a factory acceptance test or a site visit often need travel insurance and a data eSIM. The provider sets the price. TransformerPath does not quote a premium or a data plan.

Travel tools for engineers on a FAT or site visit. Affiliate disclosure. TransformerPath does not set prices.

Travel insurance (VisitorsCoverage)Travel eSIM (Airalo)

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