With respect to LIM propelled railway traction system state points of; i) Strengths of LIM ii) Weaknesses of LIM
Strengths of LIM propelled railway traction: 1) Pull produced for propelling the system is independent of adhesion between the wheels of motorized coach and rail. 2) No driving wheels and hence no associated adhesion problem. This feature permits negotiation of steeper gradients. 3) Two wheels fixed to an axle can rotate independent of each other and hence curve negotiating property improves. 4) System does not require gears therefore reduction in the associated noise level and cost of maintenance. 5) Floor height above the rail level is substantially reduced. This results in reduction in the height of bridges, diameter of tunnels along the route. 6) Avoidance of rotation of parts leads to low mechanical losses. 7) Useful for high speed levitation trains due to absence of gears and adhesion.
Weaknesses of LIM propelled railway traction: 1) The system requires laying of Al reaction rail all along the route. This considerably adds to the cost of track. 2) Reaction rail consist of Al plate backed by mild steel plate all along the route, this also increase the cost. 3) Since Al is relatively expensive material, hence chances of theft are more, hence disruption of service 4) Due to more air gap in LIM than RIM, power factor is poor and increased motor losses. 5) Due to discontinuity in the magnetic and electric circuits at entry and exit ends of motor, poor motor efficiency. 6) As power supply for traction is single phase ac power inverters are needed for operation of LIM this adds to cost.