E
Localized currents induced in an iron core by alternating magnetic
flux. These currents translate into
losses (heat) and their minimization is an important factor in lamination design.
The efficiency of a motor is the ratio of electrical input
to mechanical output. 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.
A unit of measurement of time as applied to alternating current.
One complete cycle equals 360 electrical degrees.
One cycle in a rotating electrical machine is accomplished when the rotating
field moves from one pole to the same polarity.
There are 360 electrical degrees in this time period. Therefore, in a two-pole machine there are 360 degrees in one revolution,
and the electrical and mechanical degrees are equal. In a machine with more than two poles, the
number of electrical degrees per revolution is obtained by multiplying the number
of pairs of poles by 360.
In a three-phase supply, where the voltages of the three different
phases are not exactly the same. Measured
as a percent of unbalance.
A synonym for voltage, usually restricted to generated voltage.
A motor which has its winding structure completely coated with
an insulating resin (such as epoxy). This
construction type is designed for exposure to more severe atmospheric conditions
than the normal varnished winding.
The housing or frame of the motor.
ODG Open Drip-Proof, Guarded
ODG-FV Open Drip-Proof, Force Ventilated
ODG-SV Open Drip-Proof, Separately Ventilated
ODP Open Drip-Proof
HP Vertical P-Base, Normal Thrust
LP Vertical P-Base, Medium Thrust, Extended Thrust
Prot Protected
TEAO Totally-Enclosed, Air-Over
TEBC Totally-Enclosed, Blower-Cooled
TECACA Totally-Enclosed, Closed Circuit, Air to Air
TEDC-A/A Totally-Enclosed, Dual Cooled, Air to Air
TEDC-Q/W Totally-Enclosed, Dual Cooled, Air to Water
TEFC Totally-Enclosed, Fan-Cooled
TENV Totally-Enclosed, Non-Ventilated
TETC Totally-Enclosed, Tube Cooled
TEWAC Totally-Enclosed, Water/Air Cooled
TEXP Totally-Enclosed, Explosion-Proof
IP-22 Open Drip-Proof (IEC Standard)
IP-44 Totally-Enclosed (IEC Standard)
IP-54 Splash Proof (IEC Standard)
IP-55 Washdown (IEC Standard)
WPI Weather Protected, Type I
WPII Weather Protected, Type II
The part of the motor housing which supports the bearing and
acts as a protective guard to the electrical and rotating parts inside the motor.
This part is frequently called the “end bracket” or “end bell”.
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 would prevent the ignition
or explosion of the gas or vapor which may surround the motor enclosure.
These motors are listed with Underwriter’s Laboratories.
DIVISION I – Locations 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 product explosive or ignitable mixtures.
Group C – Atmospheres containing ethyl or ether vapors.
Group D – Atmospheres containing gasoline, hexane, benzine,
butane, propane, alcohol, 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.
A motor using an external cooling system. This is required in applications where the
motors own fan will not provide sufficient cooling. These cooling systems are used in certain duty cycle applications,
with slow speed motors, or in environments with extreme dirt. Often a duct with an external blower is used
to bring clean air into the motor’s air-intake.
Device used for lifting the motor.