Fractional Horsepower Motors Types and Terms

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.

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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.linear-actuators.net)
 
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.thermocouple-assemblies.com)

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