• Armature
  The portion of the magnetic structure of a DC or universal motor which rotates
• C-Flange
  A type of flange used with close coupled pumps, speed reducers, and similar applications where the mounting holes in the f flange are threaded to receive bolts. Normally the “C” Flange is used where a pump or similar item is to be overhung on the motor. The “C” type flange is a NEMA standard design and available with or without feet.
• Capacitor
  A device which, when connected in an alternating-current circuit, causes the current to lead the voltage in time phase. The peak of the current wave is reached ahead of the peak of the voltage wave. This is the result of the successive storage and discharge of electric energy used in 1 phase motors to start or in 3 phase for power factor correction.
• D-Flange
  A special end shield with holes for through bolts in the flange and is primarily used for mounting the motor on gear boxes or bulkheads. Standardized for frames 143T through 445T. “D” flanges are not threaded and the bolt holes extend beyond the motor frame.
• DP – Drip-Proof
  An open motor in which the ventilating openings are so constructed that drops of liquid or solid particles falling on it, at any angle not greater than 15 degrees from the vertical, cannot enter either directly or by striking and running along a horizontal or inwardly inclined surface.
• Efficiency
  The efficiency of a motor is the ratio of mechanical output to electrical input. It represents the effectiveness with which the motor converts electrical energy into mechanical energy. NEMA has set up codes which correlate to specific nominal efficiencies. A decrease in losses (the elements keeping the motor from being 100% efficient of 10% constitutes an upward improvement of the motor of one code on the NEMA table. Each nominal efficiency has a corresponding minimum efficiency number
• Explosion Proof
  A totally enclosed enclosure which is constructed to withstand an explosion of a specified gas, vapor or dust which may occur within it. Should such an explosion occur, the enclosure will prevent the ignition or explosion of the gas or vapor which may surround the motor enclosure. For full explosion proof classifications, see the hazardous locations table at the bottom of this page.
• Kilowatt
  Since the watt is a relatively small unit of power, the kilowatt (kw), 1,000 watts, is used where larger units of power measurements are desirable. Generally used for rating metric motors (in place of horsepower.
• ODP – Open Drip-Proof
  An open motor in which the ventilating openings are so constructed that drops of liquid or solid particles falling on it, at any angle not greater than 15 degrees from the vertical, cannot enter either directly or by striking and running along a horizontal or inwardly inclined surface.
• Poles
  In an AC motor, refers to the number of magnetic poles in the stator winding. The number of poles is a determinant of the motor’s speed. (See Synchronous Speed) In a DC motor, refers to the number of magnetic poles in the motor. Creates the magnetic field in which the armature operates. (Speed is not determined by the number of poles).
• RPM – Revolutions Per Minute
  The number of times per minute the shaft of the motor (machine) rotates.
• Rotor
  The rotating member of an induction motor made up of stacked laminations. A shaft running through the center and a squirrel cage made in most cases of aluminum which holds the laminations together and act as a conductor for the induced magnetic field. The squirrel cage is made by casting molten aluminum into the slots cut into each lamination.
• SF – Service Factor1. When used on a motor nameplate, a number which indicates how much above the nameplate rating a motor can be loaded without causing serious degradation, (i.e., a 1.15 S-F can produce 15% greater torque than the 1.0 S-F rating of the same motor).2. When used in applying motors or gearmotors, a figure of merit which is used to “adjust” measured loads in an attempt to compensate for conditions which are difficult to measure or define. Typically, measured loads are multiplied by service factors (experience factors) and the result in an “equivalent required torque” rating of a motor or gearmotor.
• Stator
  That part of an AC induction motor’s magnetic structure which does not rotate. It usually contains the primary winding. The stator is made up of laminations with a large hole in the center in which the rotor can turn; there are slots in the stator in which the windings for the coils are inserted.
• TE – Totally Enclosed
  A motor enclosure which prevents free exchange of air between the inside and the outside of the enclosure but is not airtight. Different methods of cooling can be used with this enclosure.
• TEAO – Totally Enclosed Air Over
  Kept cool by the air flow over the motor, generally caused by the fan the motor is turning
• TEFC – Totally Enclosed Fan Cooled
  Provides for exterior cooling by means of a fan(s) integral with the machine, but external to the enclosed parts.
• XP – Explosion Proof
  A totally enclosed enclosure which is constructed to withstand an explosion of a specified gas, vapor or dust which may occur within it. Should such an explosion occur, the enclosure will prevent the ignition or explosion of the gas or vapor which may surround the motor enclosure. For full explosion proof classifications, see the hazardous locations table at the bottom of this page.

EXPLOSION-PROOF – HAZARDOUS LOCATIONS:

• Division I
  Location in which ignitable concentrations of flammable or combustible material exist and come in contact with the motor.
• Division II
  Locations in which ignitable concentrations of flammable or combustible material exist but are contained within closed systems or containers and normally would not come in contact with the motor.
• Explosion-Proof-U.L. Classifications Class I
  Those in which flammable gasses or vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures.
• Group C
  Atmospheres containing ethyl or ether vapors.
• Group D
  Atmospheres containing gasoline, hexane, benzene, butane, propane, alcohols, acetone, benzol, lacquer solvent vapors, natural gas, etc.
• Class II
  Those which are hazardous because of the presence of combustible dust.
• Group E
  Atmospheres containing metal dust, including aluminum, magnesium, or their commercial alloys.
• Group F
  Atmospheres containing carbon black, charcoal, coal or coke dust.
• Group G
  Atmospheres containing flour, starch, grain or combustible plastics or chemical dusts.