Single-phase motors are primarily used in which size category?

Single-phase motors are primarily used in which size category?

• A. Three-phase large industrial applications.
• B. Fractional horsepower sizes.
• C. High-torque heavy-duty.
• D. Variable speed drives.

Answer: (B)

Single-phase motors are chosen for small power needs because they’re simple to start, inexpensive, and easy to power from common single-phase electrical service. That makes them most common in fractional horsepower sizes, where the load is light and the high efficiency or high starting torque of larger motors isn’t necessary. In water system work, you’d see them on small pumps, valve actuators, or other small equipment that doesn’t require a lot of horsepower. For larger industrial tasks, three-phase motors are preferred due to better efficiency and higher starting torque, while high-torque, heavy-duty applications and most speed-control methods fall outside the small-power category. So the size category where single-phase motors are primarily used is fractional horsepower.

Single-phase motors are chosen for small power needs because they’re simple to start, inexpensive, and easy to power from common single-phase electrical service. That makes them most common in fractional horsepower sizes, where the load is light and the high efficiency or high starting torque of larger motors isn’t necessary. In water system work, you’d see them on small pumps, valve actuators, or other small equipment that doesn’t require a lot of horsepower. For larger industrial tasks, three-phase motors are preferred due to better efficiency and higher starting torque, while high-torque, heavy-duty applications and most speed-control methods fall outside the small-power category. So the size category where single-phase motors are primarily used is fractional horsepower.