BASIC PRINCIPLES OF ELECTRICAL MACHINES

All electrical machines are basically electro-magnetic devices. Among them the rotating machines are

electromechanical energy conversion devices but the transformer is a static machine where energy

conversion does not take place, only the level of voltage changes. 

All electrical machines are based upon three principles namely:

(i) Induction 

(ii) Interaction

(iii) Alignment. 

Transformer operation is based on induction. Most of the rotating electrical machines use the principle of

induction as well as interaction. Only a few machines such as reluctance motors are based on alignment.