Fractional horsepower motors are small motors built on a frame, and they have a power rating of less than one horsepower. Manufacturers simply refer to fractional horsepower motors as FHP motors. This categorization is usually relative to the size of the frame and the total amount of fractional horsepower in the motor. 42, 48, and 56 size frames are still considered to be FHP motors even if the motor has more than one horsepower.
The size of FHP motors is based on standards that have been established by the National Electrical Manufacturers Association (NEMA). In fact, sometimes FHP motors are called NEMA motors. In applications where low-power is needed for controlled motion, FHP motors are a popular device. From surgical devices to car windows to household appliances, the compact nature of fractional horsepower motors make them a great resource in many different industries. Even in equipment like fans and blowers, manufacturers often install an FHP motor. Read More…
Since fractional horsepower motors come in so many different types, there are different ways that they can operate. Some are fuel powered, but most of the time FHP motors run on electricity. Electric power makes it easy for these motors to have variable speeds and reversible gears. Because an FHP is a universal electric motor, it can function on alternating current (AC) or direct current (DC).
When FHP motors are used as variable speed motors, they can direct the speed of the motor to increase or decrease as desired. The low horsepower makes the speed and motion easier to control since control in an FHP motor is so precise. As was mentioned above, fuel and electricity are two possible power sources for FHP motors, but there is a third: magnets. Motors powered by magnets are called permanent magnet motors.
Electric powered fractional motors are built with a rotor, axle, coil, field magnet, and enclosure. To help conduct electrical currents, some motors also have internal brushes. Brushless motors are costlier because they require an external power supply to transfer their current. To generate power, both AC and DC FHP motors use magnets that provide motion. The magnets react with the current, causing rotation.
For small electric motors to be classified as FHP motors, they must have a power output of only 746 watts or less. While fuel-powered fractional horsepower motors are similar in their design, they use exhaust valves and a fuel chamber to generate power instead of a coil and magnet. FHP fuel-powered motors are called internal combustion engines and can be fueled using gasoline or diesel depending on the design.
Fractional horsepower motors are common in applications that range from industrial to residential use. The basic technology was invented by the scientist and inventor Nicola Tesla in 1888, at which point he patented the induction motor. Still, it wasn’t until 1915 that use and production of FHP motors began to become more widespread.
Following World War II, FHP motor manufacturing experienced a new surge as the demand for consumer goods increased. Since that time, demand for these environmentally-friendly motors has continued to grow and the number of applications that they can be used for continues to rise. Most automotive systems, power tools and appliances use FHP motors. Traits like voltage, number of phases, power supply, and frequency can all be customized for applications like these.