Fractional Horsepower Motors

About Fractional Horsepower Motors and Fractional HP Motors Including: Small Electric Motors, Small Motors, Universal Electric Motor, Universal Motor & Variable Speed Motor.

A fractional horsepower motor is a motor, built in a frame, which has power that rates smaller than one horsepower. They can be fuel powered but most often are electric. Being categorized as a fractional hp motor can be relative to the frame size as well as the amount of fractional horsepower. The frame size of the motors is based on the standards put in place by the National Electrical Manufacturers Association (NEMA). If the frame size is a 42, 48 or 56, then it can be a fractional horsepower motor even if the horsepower exceeds one horsepower. From the 56 frame on up, motors are available in horsepowers greater than those normally associated with fractionals. For instance, 56 frame motors can go as high as 5 hp. For this reason, calling motors with two-digit frame sizes "fractionals" is technically somewhat misleading. So the way a motor is deemed "fractional" is largely dependant on the manufacturer. It is important to note that each frame size designates a particular shaft height, shaft diameter and face or base mounting hole pattern.
 
These motors are used in many industries and often need to be customized. They provide power and controlled motion for smaller or low horsepower needs. They are part of small surgical devices in hospitals, in internal computer fans and as part of pumps as well as many other industrial and commercial applications. The internal power configurations are varied depending on the desired use of the motor itself. They configure electrical power into rotational energy and thus actuate the devices that they are connected to.
 
It is important to note the main components of electrical motors in general of which fractional hp motors are a type. The components of an electric motor are the enclosure, rotor, axle or shaft, coil and field magnet. Not all electric motors contain brushes, which help conduct current. When an electric motor is brushless, an external power supply is used to get the current transferred. Brushless electric motors are actually more expensive because they last longer and have fewer issues with potential sparking from high speed operation.
 
When looking for a fractional horsepower motor, the following labels are important to consider: C= face mounting, G=gasoline pump motor, H=frame with larger "F" dimension, J=jet pump motor, Y=unique/special mounting dimensions and Z=shaft extension, which is not standard, but all other mounting dimensions are standard. Fractional hp motors can be either AC or DC. Each application requires a different standard of necessities for optimum motor selection and performance. Keep in mind the voltage, frequency and number of phases of power supply needed. Custom fractional horsepower is available for uncommon situations.

Fractional Horse Power Motors and Fractional HP Motors Images Provided by Dumore Corporation

Fractional Horse Power Motors and Fractional HP Motors Images Provided by Met Motors

Types of Fractional Horsepower Motors

• AC (alternating current) motors are either induction or synchronous. They have a current that flows in either direction, usually with electric power.
  
• DC (direct current) motors have variable speed operation capabilities with current, which flows in one direction. Often use electric power.
  
• Electric motors are motors that convert electric energy into motion using magnetism. (http://www.electric-motors.net)
  
• Gearmotors are a combination of a motor and gearhead that reduce motor speed to desired RPM's. (http://www.speed-reducers.org)
  
• Integral-horsepower shunt motors are used when minimum speed variation requirements are necessary at constant potential with full to no load and/or constant horsepower.
  
• Multi-speed motors come in two, three or four speeds.  They have varying connections that can alter the speed at the starter, because of the way they are wound.
  
• Permanent magnet synchronous (PMR) motors have magnets in their rotor assemblies. These allow the rotor assembly to arrange itself in a line with the rotating magnetic field of the stator, which results in no slip and higher torque efficiency.
  
• Reversing motors can be AC or DC.  A typical DC motor is almost always reversible by changing the polarity of the field; an AC motor is reversed in a three-phase power motor by reversing connections of one leg and in a single phase by reversing the leads.
  
• Small electric motors, or fractional horsepower motors, have less than one horsepower of power.
• Synchronous motors operate up to full load at a constant speed and are often used to maintain an exact speed. The rotor speed and the rotating magnetic field speed are equal.
  
• Universal electric motors can run on either AC or DC power.
• Universal motors are capable of operating on both direct current and alternating current.
• Variable speed motors direct the rotational speed of an AC motor and can be found in many heating and cooling systems.
• Variable torque motors are essentially multi-speed motors whose loads have varying torque requirements along with varying speed requirements. Found in pumps and blowers.

Fractional Horsepower Motor Terms

Actuator - A device that creates mechanical motion by converting various forms of energy to rotating or linear mechanical energy. (http://www.iqsdirectory.com/linear-actuators/)
 
Coil (Stator or Armature) - Electrical conductors in the core slot, insulated from the iron core. They produce and transmit the magnetic field as current passes through.  
 
Commutator - A mounted cylindrical device, to which the motor brushes are attached, on the armature shaft made of copper segments set around the shaft.
 
Constant H.P. - Name used for motors with variables speeds whose loads need the same amount of horsepower despite their speed.
 
Core - The segment of the stator and rotor, usually iron; made up of cylindrical laminated electric steel.
 
Cycles per Second (HERTZ) - A complete reverse flow of alternating current during a rate of time.
 
Duty Cycle - The comparison of operating and rest times due to normal operating temperature.

Efficiency - The ratio of electrical input to mechanical output. It measures the motor's effectiveness when converting electrical energy into mechanical energy.  
 
Enclosures - Either open or closed, the frame or housing of the motor.
 
Endshield - The part of the motor housing that supports the bearing and acts as a protective guard to the electrical and rotating parts inside the motor. An endshield is often referred to as an "end bracket" or "end bell."
 
Horsepower (HP) - Work done per unit of time: 1 horsepower equals 33,000 foot-pounds of work per minute or approximately 746 watts. Motors for pumps are an example of a motor that is rated in horsepower.
 
Jackscrew - A device used for the positioning of a motor. These are adjustable screws fitted on the base or motor frame.
 
Load - The burden of the motor by its application. The required power to overcome the resistance of the machine it powers.
 
Motor - A device that turns a shaft by taking electrical energy and converting it into mechanical energy.
 
Rotor - Made of stacked laminations, the rotating component of an induction motor.
 
Shaft - The rotating part of the motor that protrudes past the bearings for attachment to the driven equipment.
 
Skew - The laminations arranged on a rotor or armature. These help abolish low-speed cogging effects in an armature and reduce induced vibration in a rotor.
 
Stator - In an AC induction motor, it is made of laminations with a large hole in the center for the rotor to turn and slots in the stator for the windings to be inserted.
 
Thermocouple - A device to detect temperature that contains two dissimilar metals which generate voltage as a function of temperature. (http://www.iqsdirectory.com/thermocouples/)

Torque - Force for turning, provided by a motor or gearmotor shaft, often expressed in pounds.