INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 9, ISSUE 01, JANUARY 2020 ISSN 2277-8616 3025 IJSTR©2020 www.ijstr.org Multispeed Operation And Testing Of Dual Stator Winding Induction Machine Anagha Soman, Dr. Rajesh Holmukhe, Dr. D.G..Bharadwaj Abstract: The massive applications of cage induction motor in industrial and agricultural sectors have promoted the interest amongst researchers to further improve the efficiency and power factor of Dual stator winding induction machines. Eventually these motors will be cost effective. This paper deals with the advancement in fabricating a new motor. The advancement proposes a common rotor of conventional cage type induction motor and two separate stator windings with different number of poles. The additional stator winding increases the reliability and improves the performance of the machine. The paper presents the testing and multispeed operation of the motor and its effect on the performance indices. Index Terms: Dual stator winding Induction machine, Dahlender, Tapped, Alexanderson, multispeed, decouple, skew. ——————————  —————————— 1 INTRODUCTION Dual stator winding is constructed by either splitting the stator or main winding or single winding into two separate windings or simply putting two different stator windings in a stator i.e. common magnetic structure [2] .The one type in which single winding gives two speed is also called as Dahlender or Alexanderson winding or Tapped winding. To reduce the magnetic coupling between two stator winding & to decouple the torque, stator winding have a two different number of poles say 2/6 poles. Power is supplied to one winding at one time and getting the required speed. Two speed motors with single winding is used where the speed ratio is 2:1 i.e all the polarities having a combination of 1:2 e.g 2/4p,4/8p,6/12p,8/16p. Squirrel cage rotor is used with the skew of one slot. The skew can be incorporated either in stator or the rotor and is Incorporated to (at least) decrease some of the harmonics if not completely eliminate them. The speciality of a squirrel cage type rotor is that it adjusts itself easily to any number of poles. However, rotor wound with same number of poles as that of stator winding can also be used .But each rotor winding requires its own set of carbon brush, own set of slip rings making the mechanical construction a complicated one for a complex machine. The machine comprises of two separate stator windings wound for different number of poles in ratio 1:3 ( e.g 2/6, 4/12 etc.) housed in the same magnetic circuit.. Three stage supply is given to the two distinctive stator windings all the while from two different variable frequency drive supplies. Hence, two different torques are produced and hence the speed now can be controlled by controlling this two different torques [1]. The analysis of machine can be done in two ways i.e. treating it as two different induction machines connected to the same shaft or the DSIM motor is considered as a six-phase induction motor [3]. 2 DESIGN CONSIDERATION 2.1 Review When a multi-speed motor is using two or more winding, each winding is to be designed for a star connection & winding is to be a series connection winding .Parallel paths are not to be used in any winding. The reason is that with parallel connection or mesh connection in one winding .It acts as a shorted secondary of a transformer drawing high current & resulting in the overheating of winding When series star connection is not possible & a delta connection is to be issued, it is to be a open delta with 4 terminals only. This connection is to be specified when delta winding is not connected to the lines. 3.Multi-speed motors are suitable for DOL/AUTO transfer starting .In case a star delta winding starting is required on either winding ,six terminals of each winding are required to be brought out, resulting in increased dimensions of terminal box. Also, it is to be ensured that the starter returns the connection to star in the off position or completely open circuit the winding. 4. When two windings are used then with the greatest number of poles is put near the core. The reason for this choice is that  The extra reactance of the high speed ,due to it being in the bottom of slot causes a drop in the power factor .The high speed winding has a better power factor as compared to low speed winding. Hence ,it can withstand the slight drop in the power factor without affecting full load current appreciably.  The low speed winding has a lower overload capacity. By putting the low speed winding near the airgap, overload capacity scarification will be avoided.  When two winding are used, a reasonable balance between copper weight I.e. areas of cross-section of the wire is to be done. Generally, the distribution of copper weight will be 40:60 for high /low speed. This is because, a higher value of current density is permissible on high speed .Also, if ratios are exceeded, it is feasible that the winding with a smaller cross section becomes too weak to handle. 3 EQUIVALENT CIRCUIT In order to find out the equivalent circuit parameters, routine tests are to be carried out i.e. Stator resistance measurement ———————————————— • Anagha Soman is currently pursuing PhD degree program in electrical engineering in Bharati vidyapeeth Deemed to be university college of Engineering, Pune. E-mail: arsoman@bvucoep.com • Dr.R.M.Holmukhe is professor in electrical engineering in Bharati vidyapeeth Deemed to be university college of Engineering, Pune. E- mail: rmholmukhe@bvucoep.com • Dr.D.G.Bharadwaj is professor in electrical engineering in Bharati vidyapeeth Deemed to be university college of Engineering, Pune. E- mail: dgb@india.com