What Is Alternating Current? Understanding the benefits of AC Industrial Motors
If you’ve been shopping for industrial electric motors, you’ve probably noticed that both AC and DC motors are available. Depending on your level of experience and expertise, you might be wondering about the difference between these two types of motors. This guide will help you understand the difference, and figure out which type is right for you.
Difference between AC and DC Current
If you aren’t interested in a quick science lesson, you can skip right to the next section to hear about the benefits of these types of motors. But for those of you who are curious, it might be helpful to learn some of the basic principles behind Alternating and Direct current. Direct current is a method of transmitting electricity with a constant voltage. In a DC circuit, the electricity always flows in the same direction and has a consistent voltage. In an alternating current, the circuit periodically reverses the direction in which the electricity is flowing, and the voltage being sent through the wire varies as well. The main benefit of DC current motors is that they are able to deliver a more consistent voltage. However, AC current is less expensive to generate and easier to transmit over long distances without much power loss. It is also much easier to increase or reduce the voltage being delivered to devices with transformers, which is why it is the preferred source for large-scale power generation.
Benefits of AC Motors Over DC Motors
While DC motors have advantages in specific applications, AC motor advantages are significant in many use cases. According to electric motor manufacturer Baldor, benefits include “reduced maintenance, reduced operating costs and continuous operation at zero speed.”
In terms of maintenance, DC motors have additional parts such as carbon brushes and a commutator that require regular care to keep your motor working effectively. Like DC motors, AC motors do still require periodic greasing of motor bearings to maintain good operating order.
For operating costs, DC also has disadvantages. Due to the variable frequency of AC, it is able to deliver a high power factor at all speeds. Conversely, with a DC motor, Baldor states that the power factor is inversely proportional to the speed. That means that the DC motor has a poorer power factor at lower speeds, which can lead to higher electricity costs over time.
Baldor also notes that DC motors cannot produce continuous torque at 0 speed without damaging the motor’s commutator. On the other hand, AC motors are able to produce full torque at zero speed continuously.
AC motors also tend to have longer life spans due to low start up power that protects components. DC motors do have other advantages worth noting. They tend to be easier to install, have high startup power and torque, and faster response times when starting, stopping, or accelerating.
With all these factors in consideration, it's no wonder that many industry observers are noting a trend that sees industry moving away from DC motors in favor of AC alternatives.
Best Applications for AC and DC motors
While AC and DC motors can both accomplish many of the same tasks, there are some industrial applications that are more common for each type of motor. This will be a major factor for you to consider when deciding what type of motor is right for you.
Traditionally, AC motors have been used for appliances, compressor drives and systems, computers, conveyor systems, fans and HVAC systems, pumps and transportation equipment. Meanwhile, DC motors are more common in fabrication and production units and machinery where constant power is essential, such as vacuums and elevators.
Looking for a new motor? Duke can help!
If you’re looking for a new A/C or D/C motor or industrial engine, Duke is an authorized dealer for dozens of top-rated brands. Our team can help you weigh the pros and cons of A/C or D/C motors for your particular needs, and help you find the motor that is right for you!
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