Major Differences between AC Motor and DC Motor

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ac and dc motor

A motor provided by AC motor supplier that converts the alternating current into mechanical power by using an electromagnetic induction phenomenon called an AC motor. This is driven by an alternating current.

The machine that converts electrical energy into mechanical energy is called a DC motor. It takes electrical power through direct current and converts it into mechanical rotation.

Here are some common differences between AC and DC motors.

AC Motor VS DC Motor:


There are two types of DC Motor; motor with brushes and without brushes.

Two types of AC motors are synchronous and induction AC motors.

Supply Sources:

In a DC motor, energy is got from cells, batteries, etc.

In an AC motor, single-phase or three-phase power is got from the main supply.

Current Input:

The DC motor will run when the DC supply is given. In the DC series motor, it runs with an AC supply.

AC motors run only when an input of alternating current is given.

Brushes and Commutators:

These are present in DC motors and absent in AC motors.

Input Supply Phases:

DC motors can only run on a single-phase supply while AC motors can run on both; three-phased and single-phase supplies.

Starting up Mechanism:

The starting mechanism of DC motors is self-starting.

In an AC motor, a single-phase requires a mechanism to start, while a three-phase is self-starting.

Characteristics of Armature:

In DC motors, when the magnetic field is stationary, the armature rotates.

In AC motors, the magnetic field rotates while the armature is stationary.

Input Terminals:

DC motors have two input terminals that are positive and negative.

AC motors have three input terminals that are red-yellow-blue (RYB). This is a three-phase terminal.

Control of Speed:

Speed can be controlled by changing the armature winding current in the DC motor.

By varying the frequency, speed can be changed in the AC motor.

Rotational Speed:

It is higher in DC depending on the setting, while it is less in the AC motor.

Change of load:

The load change shows a quick response in the DC motor while the slow response in the AC motor.

Expected Life:

As there are brushes and commutators in a DC motor, it limits the speed and reduces the life of the motor.

While the AC motor doesn’t have brushes and commutators, they are equipped and are durable.


As there is no slip and induction current loss in a DC motor, their efficiency is high. A VHS motor also has high efficiency.

Due to induction current loss and slip in the AC motor, their efficiency is less.

Frequency Maintenance:

Due to brushes and commutators in the DC motor, it requires extra maintenance. In the absence of these AC motors, the motor requires less maintenance.

Maintenance Cost:

The maintenance cost of a DC motor is more expensive as compared to an AC motor.


Where variable speed and high torque are required, DC motors are used while, where high speed and variable torque are required, AC motors are used.


DC motor is mostly used for domestic appliances while an AC motor is applied in large industries.

Bob Dylan
Bob Dylan
Bob Dylan is a distinguished content writer in the B2B marketing niche. His articles have been published in different journals and blogs, and he likes to share his knowledge through his pen. His area of expertise is machines manufacturing that is used in different industries. Follow him to know what is going on in the B2B world.

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