Electric Motors Types and Terms

  • AC motors or alternating current motors generate their magnetic field by an electromagnet powered by the same AC voltage as the motor coil. It is dispersed in single or three-phase forms with the ability for direction changes of its current cycles.
  • Brushed motors have built mechanical brushes that automatically commutate coils on the rotor as the motor rotates. Brush-type motors are more cost effective than brushless.
  • Brushless motors allow commutation of the coils on the stator by using an outside power drive without brushes.
  • DC motors or direct current motors have adjustable speed and torque applications. In a DC electric motor, there would be adjustable speed and torque along with a rotor and a permanent magnetic field stator.
  • Electric motors are motors that convert electric energy into motion using magnetism. Electric motors contrast engines because engines use fuel and electric motors do not.
  • Gearmotors consist of a gear head and motor.  Together they can reduce the speed of the motor to the preferred RPM`s. (http://www.speed-reducers.org)
  • Induction motors use electric current to generate rotation in the coils instead of delivering the rotation directly. They acquire their torque from currents produced in loops by a changing magnetic field in the field coils.
  • Permanent magnet motors have motor magnets embedded into the rotor assembly. This design allows them to align with the rotating magnetic field of the stator.
  • Servo motors have shafts that do not rotate freely; the shafts move to a definite angular location. They are often used for motion control in robots, hard disc drives, etc.
  • Stepper motors are essentially electric motors without commutators. All of the commutation handled externally by the motor controller can be stepped at audio frequencies, allowing them to spin quite quickly and be started and stopped precisely at controlled orientations.
  • Synchronous motors can operate at a constant speed up to full load. They have a series of three windings in the stator section with a rotating area; there is no slip.

AC (Alternating Current) - Current whose flow can be changed. Alternating current is commonly available in single and three forms.
 
Air Gap - The space between the rotor and stationary stator member in an electric motor.
 
Amps - The meter-kilogram-second unit of electric current that is equivalent to the steady current produced by one volt applied across a resistance of one ohm.
 
Armature - A part of the magnetic structure of a motor that rotates in a DC or universal motor.
 
Back End - The end that holds the coupling or driving pulley. Also referred to as the drive end.
 
Brush - Current conducting material that guides current from the power supply to the armature windings.
 
Commutation - Converting an electric current from direct current to alternating current. Can go both ways.
 
Core - The segment of the stator and rotor, usually iron, which is made up of cylindrical laminated electric steel.
 
Cycles per Second (Hertz) - One complete reverse of flow of alternating current per rate of time.
 
Duty Cycle - The duration and relationship of operating and non-operating times or repeatable operation at different loads.
 
Enclosures - The housing or frame of a motor in which there are two wide classifications: open and totally closed.
 
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. Often referred to as an "end bracket" or "end bell."
 
Fractional Horse-Power - A motor usually built smaller than that having a continuous rating of one horsepower. The frame size can categorize the motor as fractional also. (http://www.fractionalhorsepowermotors.com)
 
Front End - The end opposite the coupling or driving pulley. Also referred to as the commutator end.
 
Gearhead - A gearmotor part that holds the gearing, which converts the basic motor speed to the rated output speed.
 
Horsepower - A function of torque and rpm.
 
Jackscrew - A device used for the positioning of a motor. These are adjustable screws fitted on the base or motor frame.
 
Load - The burden forced on a motor by the driven machine. Often stated as the torque required to overcome the resistance of the machine it drives.
 
Motor - A device that takes electrical energy and converts it into mechanical energy to turn a shaft.  
 
Relay - A device that is effective by a variation in the conditions of one electric circuit to affect the operation of other devices in the same or another electric circuit.
 
Rotor - Made of stacked laminations, it is the rotating component of an induction motor.
 
RPM - Revolutions per minute. The number of times per minute the shaft of the motor rotates.
 
Shaft - The rotating part of the motor that protrudes past the bearings for attachment to the driven equipment.
 
Stator - In an AC induction motor the stator is made of laminations with a large hole in the center for rotor to turn and slots in the stator for the windings to be inserted.
 
Torque - Force for turning provided by a motor or gearmotor shaft. Often described in pounds.
 
Volts - The difference of possibility between two points in a conducting wire with a constant current of one ampere.