LEM Propelled Traction
- A Linear induction asynchronous linear induction motor that works on the same principle as that of other conventional induction motor but it is typically designed to directly produce motion in a straight (Linear) direction.
- Electric Motor (LEM) is an Whenever there is a relative motion between the field and the short circuited conductors, currents are induced in them which give rise to electromagnetic forces. Under the influence of this force, and according to Lenz’s law, the conductor tries to move in such a way to eliminate the induced current.
- In case of linear induction motor, the movement of field is rectilinear, the movement of the conductor is also rectilinear and this is why it is called as linear induction motor.
- The constructional of linear induction motor is same as that of conventional induction motor as shown in the Figure.
- The Figure shows the cut section of the induction motor, which is cut along the section aob and placed on the flat surface.
- The stator form the primary and consequently the rotor forms the secondary consisting of flat Aluminium conductors with ferromagnetic core for effective flux linkage. As we have seen earlier, the stator generally consists of a multi phase winding in a laminated iron core as shown in the Figure When energized from the AC supply a travelling wave magnetic field is produced.
- The direction of the travelling wave can be reversed by swapping the two phases. The secondary plate is the same as rotor. For single sided applications this is normally a conductive plate of aluminium or also of copper.
- The current induced in the reaction plate by this stator travelling field create a secondary magnetic field.