Which device may share winding and potentially have no electrical isolation between circuits?

Which device may share winding and potentially have no electrical isolation between circuits?

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

Answer: (D)

The key idea is that one winding serving both sides means there’s a direct electrical path between the circuits. An autotransformer uses a single continuous winding with taps to provide the voltage change. Because the primary and secondary are parts of the same winding, they share material and connections, so there isn’t galvanic isolation between the input and output. This contrasts with other transformers, where separate windings are electrically isolated from one another. So, the device that may share winding and potentially have no electrical isolation between circuits is the autotransformer.

The key idea is that one winding serving both sides means there’s a direct electrical path between the circuits. An autotransformer uses a single continuous winding with taps to provide the voltage change. Because the primary and secondary are parts of the same winding, they share material and connections, so there isn’t galvanic isolation between the input and output. This contrasts with other transformers, where separate windings are electrically isolated from one another. So, the device that may share winding and potentially have no electrical isolation between circuits is the autotransformer.