Describe the reason of using dc series motor for electric trains.
Electric trains require an inverse torque speed characteristics for proper operation. That is a higher torque is required at start (when speed is nil or low) and as the train picks up speed the torque needed to maintain motion is low as inertia is high. The dc series motor has inverse type output torque speed characteristics suitable for the applications where the torque required by connected loads is high at start and then diminishes to lower values as the speed increases. As the load torque speed requirements of the trains and the output torque – speed characteristics of DC series motors match, these motors are suitable for electric trains