Electric motor
Electric motors
typical DC electric motor with worm-wheel
gearbox
An electric motor is a device using electric-
al energy to produce mechanical energy,
nearly always by the interaction of magnetic
fields and current-carrying conductors. The
reverse process, that of using mechanical en-
ergy to produce electrical energy, is accom-
plished by a generator or dynamo. Traction
motors used on vehicles often perform both
tasks.
Electric motors are found in myriad uses
such as industrial fans, blowers and pumps,
machine tools, household appliances, power
tools, and computer disk drives, among many
other applications. Electric motors may be
operated by direct current from a battery in a
portable device or motor vehicle, or from al-
ternating current from a central electrical
distribution grid. The smallest motors may be
found in electric wristwatches. Medium-size
motors of highly standardized dimensions
and characteristics provide convenient mech-
anical power for industrial uses. The very
largest electric motors are used for propul-
sion of large ships, and for such purposes as
pipeline compressors, with ratings in the
thousands of kilowatts. Electric motors may
be classified by the source of electric power,
by
their
internal
construction, and by
application.
The physical principle of production of
mechanical force by the interaction of an
electric current and a magnetic field was
known as early as 1821. Electric motors of in-
creasing
efficiency
were
constructed
throughout the 19th century, but commercial
exploitation of electric motors on a large
scale required efficient electrical generators
and electrical distribution networks.
History and development
Jedlik’s first successful electromagnetic "self-
rotor" in 1827 (Museum of Applied Arts,
Budapest)
From Wikipedia, the free encyclopedia
Electric motor
1
Ányos Jedlik’s electric motor used electro-
magnets for both stationary and rotating
parts (Hungary, 1828).
Jedlik’s electric motor-propelled vehicle
(1828).
The principle
The principle of conversion of