Condition for the Occurrence of Maximum Efficiency in Induction Motors and Transformers

The article presents theoretical considerations regarding the condition for the occurrence of maximum efficiency in a squirrel-cage and slip-ring induction motor as well as in a transformer. These considerations cast a new look at the above issue and allow to formulate more precise conditions for the occurrence of maximum efficiency, indicating the equality of no-load losses and losses caused by secondary current in both windings in induction motors and transformers. The presented conditions for maximum efficiency are consistent with the operating conditions of these machines. The dependency on the value of the relative power load for which the maximum efficiency occurs is also formulated.