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DC Motors and Their Variants

Rotary electric motors are salient pieces of technology that find use in a number of applications, including marine, pipeline compression, and other industrial devices. When choosing an electric motor, customers are often presented with a myriad of options with different qualities, but generally, the biggest determining factor is the power source, which may be alternating current (AC) or direct current (DC). Although AC motors are capable of providing significant power output as needed, the DC motor is more efficient in its energy usage. In this blog, we will discuss everything you need to know about rotary DC electric motors, including their design, variants, and applications.

DC motors generate mechanical energy from the conversion of direct current electrical energy. Using the same operating principle and components, DC motors can be scaled to fit the needs of a diverse set of applications, ranging from small appliances to large ships. The two primary components of a DC motor are the stator and armature. The prefix "stat" refers to the component's stationary nature, while "or" describes its function as a rotor. When powered by direct current, the stator generates a magnetic field, which acts on the armature to create motion. The difference between motors of various designs comes primarily from how and when the current is applied to these elements. We will now dive into the most common types of DC motors available.

1. Brushed DC Motor

This DC motor design is the oldest and one of the most utilized today. For low-end applications not requiring much power or accuracy, the brushed DC motor can be a sufficient, cost-effective option. Unlike later motors, which rely heavily upon electronic components, brushed motor assemblies are entirely mechanical. In order to rotate the armature, a pair of carbon-based brushes are installed exactly 180 degrees opposite from each other. These brushes conduct current to two contact plates, called commutators, which each account for 180 degrees of the entire assembly. As a result, every half-turn in the motor causes a switch in the current flow.

2. Separately Excited DC Motor

In general, the stator and armature elements are both powered by the same source. This configuration suffices for most applications, but in the context of high-speed variability, it is beneficial for each to receive power from a separate source. However, in order to achieve accurate control of this motor type, the DC voltage supply to the stator must remain fixed.

3. Permanent Magnet DC Motor

These motors are smaller and less expensive than other variants, but they can only be used in circumstances in which there is no need to control motor speed. This is because they implement a fixed, permanent magnet to produce the field. Since permanent magnet motors lack a stator, they can be made very compactly, affecting both size and economy. However, any time a permanent magnet is used, there always remains a slight chance of demagnetization.

4. Brushless DC Motor

Instead of needing brushings to conduct a current, brushless DC motors make use of electronic commutation elements. Without the constant friction being created between brushes and commutation elements, brushless motors can reach higher speeds while producing less noise. Additionally, despite their higher upfront cost, brushless motors operate with higher efficacy and low power loss.


Regardless of the DC electric motor your application calls for, NSN Gamut has you covered with fair prices, rapid lead times, and a diverse inventory. Owned and operated by ASAP Semiconductor, we give customers direct access to over 2 billion new, obsolete, and hard-to-find components serving the aerospace and industrial markets. Explore our expansive offerings by visiting our various part catalogs, or use our comprehensive search engine to find the exact component you need. Once you are satisfied with a particular item, you may begin the purchasing process at any time by completing an Instant RFQ form as found on our website.


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