A compliance discussion should move beyond asking whether a transformer is ‘CE certified’. The useful questions are which standard applies, which part and configuration were tested, and who holds the technical evidence.
Match the standard to the product
EN 61558 covers transformer safety, but the applicable part depends on the transformer type and application. Medical equipment uses additional end-product requirements, and not every generic transformer test proves suitability.
Record the exact product designation, ratings and construction covered by the evidence. A family certificate should not be assumed to cover arbitrary changes.
Define documents and owners
Ask for the declaration of conformity, test reports, drawings, change-control rules and label requirements relevant to the supplied configuration.
The equipment manufacturer, importer and manufacturing partner may have different legal responsibilities. Confirm them before launch and keep the evidence with the product technical file.
Control every product change
A winding, core, insulation, potting or terminal change may affect critical characteristics. Document whether the change needs electrical verification, type evidence or customer approval.
Production records should identify the exact approved revision shipped with each batch.