Which transformer type provides galvanic isolation between primary and secondary windings?

• A. Two-winding transformer
• B. Autotransformer
• C. Isolation transformer
• D. Single-winding transformer

Answer: (A)

Galvanic isolation means there is no direct electrical path between the primary and secondary sides. In a two-winding transformer, the primary and secondary are separate coils that are magnetically coupled through the core. Since there’s no direct conductor connecting the two windings, energy passes only via magnetic coupling, keeping the circuits electrically isolated from each other.

Autotransformers use a single continuous winding with taps, so parts of the winding are common to both sides; that shared electrical path means there is no isolation. Isolation transformers are designed specifically to provide isolation, but they achieve it because they are two-winding devices with separate windings. A single-winding transformer isn’t designed for isolation and wouldn’t provide galvanic isolation.

So the two-winding transformer provides galvanic isolation between the primary and secondary windings.