The relationship between the operating time and the resting
time of an electric motor. Motor ratings according to duty are:
Continuous duty, the operation of loads for over one hour.
Intermittent duty, the operation during alternate periods of load and rest.
Intermittent duty is usually expressed as 5 minutes, 30 minutes or one
hour.
Efficiency:
A ratio of the input power compared to the output, usually
expressed as a percentage.
Enclosure:
The term used to describe the motor housing. The most
common industrial types are: Open Drip Proof (ODP), Totally Enclosed
Fan Cooled (TEFC), Totally Enclosed Non-Ventilated (TENV), Totally
Enclosed Air Over (TEAO). (See Chapter IV for additional information).
Endshield:
The part of a motor that houses the bearing supporting the
rotor and acts as a protective guard to the internal parts of the motor;
sometimes called endbell, endplate or end bracket.
Excitation:
The act of creating magnetic lines of force from a motor
winding by applying voltage.
Explosion-Proof Motors:
These motors meet Underwriters Laboratories
and Canadian Standards Association standards for use in hazardous (explosive)
locations, as indicated by the UL label affixed to the motor. Locations
are considered hazardous because the atmosphere does or may contain
gas, vapor, or dust in explosive quantities.
