A transformer with a turns ratio greater than one is classified as what type?

A transformer with a turns ratio greater than one is classified as a step-up transformer. This means that for every turn in the primary winding, there are more turns in the secondary winding, which results in an increase in voltage from the primary circuit to the secondary circuit. The greater the turns ratio, the higher the voltage can be transformed.

This type of transformer is typically used when voltage needs to be increased for transmission over long distances, making it more efficient by reducing energy losses associated with higher current levels. Step-up transformers play a critical role in power distribution systems and in applications where higher voltage is required for specific equipment or processes.

In contrast, options like a step-down transformer would decrease the voltage, an isolation transformer primarily serves to decouple two circuits, and an auto transformer uses a single winding to serve both functions without providing electrical isolation. Each of these alternative types serves unique purposes that are distinct from the function of increasing voltage provided by a step-up transformer.