Electrical motors are crucial in almost any industry. Using the most appropriate type of motor can make a huge difference to your facility and energy consumption.

AC and DC motors are two common types of motors used in industrial machinery. There are several key differences between these two kinds of motor, and it’s important to be aware of the advantages and disadvantages of both.

 

In addition to choosing the right type of motor and ensuring it is sourced from a reputable manufacturer that uses high-quality parts, you should also implement a regular maintenance schedule to prevent damage and minimise the risk of downtime.

In this article, we explore the key differences between AC and DC motors to help you decide which is best suited to your needs.

 

What is an AC motor?

An AC motor is an electric motor that’s driven by an alternating current (hence “AC”). This type of motor is less familiar than a DC motor (which we’ll come to soon) and are typically used in various everyday industrial applications as well as a range of other professional equipment and products. 

This type of motor is an efficient method for producing energy from an electrical input signal. Energy is obtained from magnetic fields that are generated through coils which are wrapped around the output shaft. AC motors consist of several components including a stator and rotor. 

AC motors rely on alternating the current flow around the circuit to produce mechanical energy and are distinguished from DC motors by various critical criteria. They generally have a longer life expectancy than DC motors too, and offer an efficient and durable method of power generation. 

 

 

Two common types of AC motors are:

• Synchronous: This type of motor rotates in line with the frequency of the energy supply current and is used in a wide variety of applications.

• Induction: These motors are simple and robust, consisting of a wound stator and a rotor assembly. Here, the electric current necessary to turn the rotor comes from the electromagnetic induction caused by the stator winding. They’re one of the most common types of motor available. 

What is a DC motor?

In contract, a DC motor is one that converts electrical energy into mechanical energy using electrical power obtained through a direct current. 

This type of motor uses magnetic fields that occur as a result of the electrical currents generated to power the movement of the rotor. The speed and torque of the motor depends on the electrical input, along with the design of the motor itself.

Energy for a DC motor comes from batteries or a generated power source that delivers constant voltage. These motors are composed of several parts, including bearings, shafts and gears. They provide better speed variation and improved control compared to AC motors. 

 

 

Two types of DC motors include:

• Brushed: These are a relatively old kind of motor made up of a rotor, brushes, and an axle. The speed and direction of the motor is controlled by the charge and polarity of the brushes.

• Brushless: Brushless motors are made up of the same components as a brushed motor, simply without the brushes. They’re much more efficient and feature magnets mounted near the rotor to improve efficiency.

DC motors can be found in elevators, hoists, steel rolling mill drives, turntables, conveyor belts, mixers, printing presses, extruders, and more. These motors used direct current (DC) as opposed to alternating current (AC) and their speed can be adjusted by either adjusting the static field current or the voltage that is applied to the armature.

 

What is the difference between an AC motor and DC motor? 

There are many differences between these two types of motors. The most notable is the type of current required to convert energy: alternating (AC) and direct (DC).

AC motors are typically considered to be a more powerful solution than DC motors as they generate higher torque through a stronger current. However, DC motors are regarded as a more efficient option as they allow for better speed control and regulation of their input energy. 

 

Here’s a closer look at the key difference areas between AC and DC motors:

Input Power

AC motors operate using an alternating current as an input electrical signal. This changes the speed and direction of the motor during the cycle. They can be operated from a single-phase power source or a polyphase source. Alternatively, DC motors are powered by a single direction current supplied by the power source. 

Speed Control

Motor speed is controlled by the input frequency of the alternating current and it is proportional to this in an AC motor. When the alternating current frequency increases, so does the speed of the motor. In a DC motor, speed is controlled by altering the voltage and current supplied to the coils and is also proportional. 

Performance

AC motors are regarded for their speed and variable rotation force, but it’s important to note that torque can drop when the speed of the motor increases. DC motors are valuable when it comes to speed control and are also capable of producing a higher torque than AC motors. They are also typically more responsive to load changes. DC motors are also more energy efficient than AC motors, with brushless motors offering better efficiency than brushed motors.

 

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Preferred Spares is one of the leading suppliers of AC and DC motors and a wide range of industrial automation parts in the UAE.

Offering expedient delivery and expert advice, head to the Preferred Spares website for all your industrial machinery needs or to check out the full range of motors, softstarters and spare parts from the world’s leading manufacturers.