Difference Between AC and DC Motor

The AC Motor and the DC Motor are differentiated on the various factors like the source or the nature of the power used in the motor. The commutation process, types, starting of the motor, a number of terminals. Applications of the motor, usage of brushes, and the maintenance cost of the motor.

Content: AC Vs DC Motor

    1. Comparison Chart
    2. Definition
    3. Key Differences

Comparison chart

Nature of the Input CurrentAlternating Current is the main input power in the AC motorDirect Current is the main input power in the DC motor
Supply Sources Three phase or single phase power from the supply mainsEnergy is obtained from batteries, cells etc.
Commutation ProcessAbsent in AC motorPresent in DC motor
Supply PhaseBoth single phase and three phase supply are usedOnly single phase supply is used
Number of terminalsThere are 3 input terminals RYB.There are two input terminals Positive and negative
Carbon brushesNo carbon brushesThere are carbon brushes in the DC Motor
ApplicationsSuitable for large and industrial applicationsDC motor is used in small and domestic applications
StartingAC Motor are not self starting. It requires some external starting equipmentsDC Motor are self starting
Position of ArmatureThe Armature is stationary and the magnetic field rotatesArmature rotates while the magnetic field remains stationary.
Maintenance costLess expensive as compared to DC MotorDC Motor maintenance is more expensive.

Definition of AC Motor

In an AC Motor, an alternating current passes through the coils. When an alternating current is passed through the electromagnets a magnetic field is generated. Stationary parts consist of electromagnets. The magnetic field which is created changes constantly. The interaction between the electromagnets and the magnetic field makes the motor rotate.

Definition of DC Motor

A Direct current is passed in the stationary part of the motor, which is known as the Stator. A coil of wires which carry an electric current is known as Rotor. A DC motor converts electric power into mechanical power.

Key Differences Between AC  Motor and DC Motor

  1. AC motor works on the concept of alternating current, whereas DC Motor works on the direct current.
  2. The main source of the AC motor is current coming from the three-phase or the single-phase supply mains. The sources of the DC motor are batteries and cells.
  3. In an AC motor, the commutation process is absent hence, there is no use of carbon brushes, whereas in a DC motor the commutation process takes place and thus the carbon brushes are used.
  4. Both three-phase and single-phase supply are used in an AC Motor but in DC Motor only a single-phase supply is used.
  5. In an AC motor, there are three input terminals known as RYB (Red, Yellow, and Blue). In DC motor, there are only two terminals, these are known as Positive and Negative.
  6. AC motors are not self-starting, and thus, it requires some external equipment to start the motor initially. DC motors are self-starting motors.
  7. The armature is stationary, and the magnetic field rotates in the AC motor but in DC motor the armature rotates, and the magnetic field is stationary.
  8. AC motor is suitable for large and industrial applications whereas DC motors are used for small and domestic applications.
  9. The maintenance cost of the AC motor is more as compared to that of a DC Motor.

The above discussed are the points of comparison between AC and DC motor.

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