noun
transformer; impedance transformer
Technical term for an electrical device that transfers energy between circuits, often changing voltage or impedance.
変成器は交流電圧を変えるために使われる。
A transformer is used to change AC voltage.
Specifically a voltage transformer; 変成器 can also refer to impedance transformers.
Compound of 変成 (transformation) + 器 (device). The exact historical derivation is uncertain; the spelling is conventionally associated with electrical transformers.