Wednesday, October 3, 2012

The Linear Induction Motor






Somewhere in 1985 there was a seminar held at REC NIT Calicut for a few days called STEPS meaning "Seminar on Technical Education problems and solutions" and alongside this event there was an exhibition for the public and the public walked through the various departments and every department created something as an exhibit.


As part of this event the seminar found representations from many other REC's of the time..Mr. Basavaraj the principal of KREC Suratkal and Mr. Rao the principal of REC Allahabad had come and spoke in the plenary session which was held in the newly created seminar hall above the office of the principal. Students from REC Trichy whose names I do not recollect had also made their presence and were housed in the International Hostel. Being a senior student myself I was involved in the organizing activities.



As part of these festivities every lab of REC  was busy preparing some exhibit and the Electrical Department was not to be left behind and the Machines lab eventually was resplendent with many exhibit and bulbs dimming and glowing at many places...and electrical motors working in oscillatory motion ..and many such things that must have fascinated the public and among the exhibits was something novel the "Linear Induction Motor"..Though I was not directly a member of the team that created the motor I was very much around as a well wisher. Shankara Narayanan; Manjeet Singh Rekhi and George John had some direct association with this project..and Dr. Gerwadis...Mr. Suresh Kumar ..and Dr. Prabhakaran were the faculty enthusiasts. I feel sorry that this model that was made by students with the help of faculty was not confined in some enclosure and preserved for the future to see... a fully working model of a Linear Induction Motor.



Linear Induction motors create magnetic traction and levitation. Magnetic traction through a space displaced winding drawn linearly and fed with a time varying current which is phase displaced. This is very easy to say theoretically but now Iam at loss now to describe as to how these windings were precisely laid out. It was possibly connected into a star node at one end with sufficient windings to create both resistance and reactance to create the necessary impedance to withstand the voltage that was being fed ..which means a well formed magnetic base was created for the windings. Couple of evenings previous to the event were spent winding the motor and I was helping my cronies by straightening the wire wearing a cotton glove.The time was set to test it..somewhere in the evening..and a toy like metal train possibly made with aluminium was  placed on the windings and power fed slowly using a dimmerstat and we could not believe that the train was moving over the windings..its speed dependent on the level of voltage fed and many around were exclaiming the sight that they doubted but became true.



During the exhibition many people around came to see our train...and some of the students were explaining it to the general public. possibly in its own way REC NIT Calicut made a model of Magnetic traction around which bullet trains and similar trains work and showed the world how a little ingenuity would create something worth the while and may be the model so created by our students back in 1985 would be some kind of basis around which traction would work in this country in the future.

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