The type of transformer which does not provide electrical isolation

The type of transformer which does not provide electrical isolation:

1. Potential transformer
2. Current transformer
3. Distribution transformer
4. Auto-transformer

Correct answer: 4. Auto-transformer

Auto-transformer is the type of transformer that doesn’t provide electrical isolation. In an autotransformer, there is a direct physical connection between the primary and the secondary circuits, so there is no electrical isolation in the auto-transformer.