Classified by moisture-proof method: open transformer, potting transformer, sealed transformer.
Classification by core or coil structure: core-type transformers (insert core, C-type core, ferrite core), shell-type transformers (insert core, C-type core, ferrite core), Toroidal transformers, metal foil transformers.
According to the number of power phases: single-phase transformer, three-phase transformer, multi-phase transformer.
Classification by use: power transformers, voltage regulating transformers, audio transformers, intermediate frequency transformers, high frequency transformers, pulse transformers.