AC vs. DC Motors: What’s the Difference?

The right electric motor can make or break a facility’s productivity and efficiency. Understanding the differences between alternating current (AC) and direct current (DC) motors lets you assess your operation’s needs and select the best option for the job. Use the guide comparing AC vs. DC motors to help you ensure your facility has the best tools for achieving success. 

Understanding Electric Motors

Electric motors help power essential processes. They rotate, turning electrical energy into mechanical energy, generating power and movement. Choosing an electric motor means starting with your type of current. The current your electric motor uses influences the job it does and the efficiency of your work. 

Alternating current and direct current are your two options for electric motors. Each one operates slightly differently, influencing their power and mechanics. 

AC vs. DC

AC and DC electric currents share several differences, but the main one is how each current works. AC flows in both directions, changing as it moves in one direction and then reversing to generate power. You’ll see AC motors used in household appliances like water heaters and industrial machinery like hydraulic pumps. They’re popular thanks to their simple design, durability and ability to generate high torque at lower speeds. 

DC flows in one direction the entire time. You’ll recognize it as being the current Thomas Edison developed and popularized. DC works well when you need precise speed control, although it’s harder to convert it to lower or higher voltages than AC. Its efficiency and easy-to-control nature make it ideal for products like computer disk drives and electric vehicles. Additionally, you’ll have to choose from two sub-types of DC motor — brushed and brushless:

• Brushed: Brushed DC motors have internal components that include a communicator and brushed. The brushes brush against the communicator to change the current’s direction, creating the rotational machine that creates mechanical energy. 
• Brushless: As the name states, brushless DC motors don’t have communicators or brushes. Instead, they use electronic controllers to influence the current’s direction and timing. This design gives you more precise control over the motor and reduces the physical contact with the internal components. 

Brushed motors are less expensive and they’re simple, but they have limited durability and efficiency. They’re also higher maintenance than brushless DC motors since the internal brushes cause increased friction and wear. 

With brushless motors, you get an improved life span, maintenance and efficiency compared to brushed DC motors. However, this also means brushless motors are more expensive. Their precision and life span mean brushless motors are seen more commonly in industrial automation. 

What’s the Difference Between AC and DC Motors? 

The difference between AC and DC motors mainly comes down to the current direction, but other factors affect your choice, too. Weigh your needs with each electric motor’s features to help you find the right option. Here’s a breakdown comparing DC vs. AC motors so you can make the best choice:

Efficiency

AC motors generally have better efficiency than DC motors, especially when comparing higher power levels. DC motors with brushes will have less efficiency than AC motors since the brush creates friction, wear and energy loss that impacts efficiency. AC motors also feature the ability to better optimize electric motor designs for specific conditions. However, brushless DC motors have come a long way — new technology allows brushless motors to compete more closely with AC motors in terms of efficiency. If you’re going with a brushless DC motor, you can get close to AC motor efficiency. 

Speed

AC motors are well known for their adaptability to different speeds. Since AC motors perform well at a range of different speeds, they’re preferred for applications that need constant torque or variable speeds. Conveyor belts, fans and pumps are all situations that call for AC motors. With variable frequency drives (VFDs), you can adjust the frequency of the electric motor’s power supply and control its speed. 

DC, on the other hand, performs best when it comes to speed control and speed regulation. If you need precision, brushed DC motors offer the best speed control. Use DC motors for applications that need variable torque or constant speed, like electric vehicles, robotics and power tools. 

Cost

AC motors are reliable, cost-effective options for high-power jobs since they often feature simpler construction and can perform various jobs with minimal tweaking. Additionally, AC motors require less maintenance — they don’t have brushes and will see less wear and tear than brushed DC motors. This means you’ll pay less to maintain them long-term, and they’ll last longer than brushed motors. 

DC motors are essential for applications that have limited space or need precise speed control. These electric motors’ abilities justify their higher initial costs through their performance trade-off. You get superior performance for your specific applications, saving you money through improved productivity and quality. These performance improvements help balance out the higher upfront and maintenance costs for some operations. 

Which Motor Is Right for You?

Choosing the right electric motor for your industrial facility is essential to ensure you get the best performance and efficiency out of your operation. Now that you understand the key differences between AC and DC electric motors, you should assess your facility’s needs. Break down these factors to help you find the best electric motor for the job:

• Application requirements: Figure out your application’s needs first. Decide what power, speed, torque and duty cycle your application needs to operate effectively. If your application needs constant torque and variable speed, consider AC motors with VFDs. If speed control and high starting torque are essential, consider DC motors. 
• Environment: Environment affects how your electric motor performs and how long it lasts. Industrial facilities often have environments with a range of vibrations, temperatures, humidity and hazardous conditions. All of these things can reduce your electric motor’s life and efficiency. Choose motors with the right enclosures, protection ratings and insulation classes to help them stand up to these harsh conditions. 
• Space: You’ll also need to look at your space for the electric motor. Brushless DC motors offer more compact designs that work well in tight spaces, while other electric motors might need more space for ventilation and maintenance access. 
• Cost: Cost is always going to play a role in your decision. Break down each electric motor’s expected costs — like initial purchase, maintenance, expected life span and efficiency. While AC motors offer lower upfront and maintenance costs, they might not fit the application. Some DC motors can offer better efficiency, while others will have higher maintenance costs. Talk to your electric motor expert for assistance in finding the best fit for your needs. 

Get Electric Motors From Industrial Electric Company

If you’re looking to upgrade your electric motors at your facility, choose the experts at Industrial Electric Company. As a one-stop solution for electric motor services, we offer comprehensive electric motor repair, installation and preventative maintenance services. Our certified technicians deliver effective repairs and lasting maintenance services so you can stay productive. 

Located in Modesto, California, our state-of-the-art facility serves businesses across central and Northern California and western Nevada. Count on us for turnkey installations, minimizing downtime and maximizing efficiency. Experience excellence in electric motor services with Industrial Electric Company. Make us your partner in powering reliability — contact us online today!