Difference between ac and dc motor

We all know that both AC and DC motors serve the actually same function of converting electrical energy into mechanical energy, they are powered, constructed and controlled differently. The most basic difference between AC motor and DC motor is that AC motor power on AC current while DC motor power on DC current, to learn in detail about AC and DC motor difference is given below. 

The main key difference between AC and DC motor are given below:
  • AC motors are powered from AC current while DC motors are powered from DC current.
  • AC motor conversion of current is not required while DC motors conversion of current is required like DC current.
  • The main source of the AC motor is currently coming from the three-phase or the single phase supply mains while the sources of the DC motors are batteries and cells.
  • In AC motor there are three input terminals known as RYB while in DC motor are only two terminals. They are known as positive and negative.
  • AC motor is used where power performance is sought for extended periods of time, DC motors are used where motor speed required to be controlled externally.
  • AC motor can be single phase or three phases while DC motors are single phase.
  • AC motors armatures do not rotate while magnetic field continuously rotates, while in DC motors the armature rotates while the magnetic field does rotate.
  • AC motor is suitable for large and industrial applications while in DC motors are most commonly used for small and domestic applications.
  • AC motors do not use brushes, DC motor uses brushes.
  • AC motors are not self-starting and thus it requires some external equipment to start the motor initially, DC motor is self-starting motors.
  • AC motors have a longer life span, DC motors have not longer life span.
  • The maintenance cost of the AC motor is more as compared to DC motor.
  • AC motor requires effective starting equipment like a capacitor to start operation while DC motor does not require any external help to start operation.
  • The speed of AC motors is simply controlled by varying the frequency of the current, The speed of DC motors is controlled by varying the armature winding current.
  • Efficiency of AC motor is less while the efficiency of the DC motor is high as there is no slip and induction current loss.

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