The most efficient electrical machine is the transformer. Transformers have efficiency above 95%. The autotransformer has an efficiency of close to 98%. The maximum efficiency is achieved under the fully loaded condition.
![Which is the most efficient electrical machine? 1 Power Transformer](https://www.electricalclassroom.com/wp-content/uploads/2019/07/Power_Transformer-FAQ.jpg)
The most efficient electrical machine is the transformer. Transformers have efficiency above 95%. The autotransformer has an efficiency of close to 98%. The maximum efficiency is achieved under the fully loaded condition.