Behind every precise machine movement lies a silent rivalry: AC vs. DC.  

Servo motors fall into these two categories depending on their power source. Inside each servo, a tiny motor generates rotation, an encoder tracks the shaft position (letting the servo know its position and adjust if necessary), and the controller, acting as the “brain,” sends signals to the motor until the desired position is reached. Working together, they control angular or linear position and velocity, operating within a closed-loop system for precise motion control. 

But what are the specific differences between the two, and how do you know which one is right for you? 

AC Drives, often referred to as Variable Frequency Drives (VFDs), are powered by alternating current and are more suitable for high-power and high-precision applications. This includes industrial robotics, CNC machinery, and automation systems. AC servo motors are typically brushless, making them more efficient and lower-maintenance since there are no brushes or commutators to replace. Because of their advanced electronics and control software, they can be more complex, but that complexity allows for seamless integration with modern PLCs and networked systems. 

DC servo motors, on the other hand, are powered by direct current (DC) and are generally simpler and more cost-effective for certain applications. Traditional brushed DC servos have high starting torque, which is excellent for heavy loads or low-speed control, and they’re easy to operate with straightforward drive electronics. However, they require brushes and a commutator, which means more maintenance and mechanical wear over time. The brushed versions are still common in legacy systems and small-scale robotics. 

We’ll make deciding between the two simple; A DC motor is best suited for operations needing high starting torque at very low speed, like cranes, hoists, or legacy retrofits where replacing the DC system would be too costly. An AC motor is ideal for nearly all new installations, especially where energy savings, low maintenance, and network integration are priorities; Think fans, pumps, compressors, robotics, and motion-controlled machinery. 

Industrial Repair Service is equipped to handle any mechanical or electrical issues your servo motors may encounter. All repairs undergo rigorous quality assurance and must meet stringent performance standards before leaving our facility. Call us today!