Question

Why are the DC motors preferred for traction applications?

(a) Torque and speed are inversely proportional to armature current

(b) Torque is proportional to armature current

(c) Torque is proportional to square root of armature current

(d) The speed is inversely proportional to the torque and the torque is proportional to square of armature current

I have been asked this question in an online quiz.

Enquiry is from Applications of DC Machines in division DC Machines of DC Machines

Answer 1

Correct choice is (d) The speed is inversely proportional to the torque and the torque is proportional to square of armature current

The explanation is: DC motors are used for traction as, according to the characteristics of DC motors speed is inversely proportional to torque and square of armature current as well, if linear magnetization is concerned. Thus, DC motors are perfectly suitable for traction.