Why dc motor is not named as conduction motor?

Answer 1

In dc motors, the electric power is conducted directly to the armature (i.e., rotating part) through brushes & commutator. Hence, in this sense a dc motor can be called as a Conduction motor.

However, in ac motors, the rotor does not receive any electric power by conduction but by induction in exactly the same way as the secondary of a two winding transformer receives its power from the primary. That is why such motors are called as Induction motors. An induction motor can be treated as a rotating transformer i.e., one in which primary winding is stationary but secondary is free to rotate.

Answer 2

An 'induction motor' has no electrical connection between the field windings and the armature windings. On this basis, a motor (such as a d.c. motor) that does have an electrical connection between these windings could be called a 'conduction motor' but, in practise, the term isn't used.