Constructional Features of Induction Machines : Stator Construction

Induction motors are most commonly used motors in both industrial as well as domestic sector. In Induction Machines Basics, we discussed various basic concepts of induction motors and various methods or thing on the basis of which Induction machines can be classified and in Advantages and Applications of Induction Motors we discussed various applications of induction motors and advantages of these machines over other machines. So when we know that Induction motors are of great importance and are very advantageous, so lets discuss construction of induction motors in detail in this article.

Construction of 3 Phase (3Φ) Induction Motor

A three phase Induction Motor or 3Phase Induction Motor is mainly contains two essential parts viz. Stator and Rotor. These two parts are the compulsory parts of an Induction motor. Here we’ll discuss both these parts in detail with all its main points from the point of view of designing.

Stator

Stator is the stationary part of the Induction motor. It is the part to which supply is given. Material Used To Built : It is one of the most common question asked in various interviews of Electrical Engineering discipline, Here is the answer to this question. Stator of Induction motor is built up of the low hysteresis loss or high permeability material such as CRGO (Cold Rolled Grain Oriented) Silicon Steel. Eddy Loss Reduction : It is the another most important interview question for Electrical Engineers. How eddy current losses are reduced in various machines including Induction motors ? To understand this you have to understand what is eddy current and eddy current loss ? Technically whenever flux is changed in a core, in accordance with Faraday’s law of Electro-Magnetic Induction, an emf is induced in the core and as the core is short circuited, this results in the current which is termed as eddy current. Some energy is dissipated in form of heat due to this current and this is called eddy current loss. It depends upon the thickness of the sheet of core because more thick the core is there more content or material will be there and hence more emf will be induced resulting in more eddy losses. So the point is to reduce eddy current loss we will have to reduce current, for which induced voltage have to be reduced and this is possible by limiting thickness of the sheet. Hence Eddy current loss are reduced by using thin laminated sheets to construct the stator of the machine. Stator Frame : These stator laminations require a base to be mounted and this base is termed as stator frame. This is usually made up of Cast Iron or Steel with slots in it. These slots are used to host stator winding. Stator winding is supplies with AC supply and this produce magnetic field in the stator of the machine. This three phase winding may be connected in Star arrangement or in Delta arrangement. This image shows the arrangement of all parts of an induction motor. It includes Stator Frame, Stator Laminations, Stator slots, Air Gap, Rotor slots, Rotor conductors, Rotor laminations and finally shaft.