Which type of motor can operate on either AC or DC power?

A universal motor is specifically designed to operate on both alternating current (AC) and direct current (DC). This versatility comes from the construction of the motor, which typically features a series winding and a commutator that allows it to function efficiently with both types of current. Universal motors are often found in applications requiring high speed and variable speed control, such as in portable power tools and household appliances.

In contrast, a capacitor-start motor is a type of induction motor that typically runs on AC power and requires a capacitor to start. It is not designed for operation with DC, limiting its application scope. A split-phase motor, which is also an AC motor, operates on single-phase alternating current and utilizes phase splitting to start, making it unsuitable for DC operation. Lastly, a 3-phase motor operates exclusively on three-phase alternating current and cannot function with direct current. Thus, the universal motor stands out as the only option that can efficiently use both AC and DC power sources.