The Induction Machine Handbook

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The level of prosperity of a community is related to its capability to produce
/ n: |% J3 F2 x4 \/ a# ]: Pgoods and services. But producing goods and services is strongly related to the
use of energy in an intelligent way.
  e0 B$ Q6 @0 ?' s: E( MMotion and temperature (heat) control are paramount in energy usage.
Energy comes into use in a few forms such as thermal, mechanical and
: D2 i/ J% ?+ B! O7 o1 Selectrical.
Electrical energy, measured in kWh, represents more than 30% of all used
energy and it is on the rise. Part of electrical energy is used directly to produce
- v# {: @. e# Z! j. l/ l" Sheat or light (in electrolysis, metallurgical arch furnaces, industrial space
; i; D4 f8 R6 \7 nheating, lighting, etc.).
& Y3 r* J* n0 m: ~The larger part of electrical energy is converted into mechanical energy in
) r/ M" U' H. v$ T! Z, J3 Velectric motors. Among electric motors, induction motors are most used both for
! M" j1 ^. B2 {3 r3 R' Yhome appliances and in various industries [1-11].
. _7 k" H2 |* Y/ H* nThis is so because they have been traditionally fed directly from the threephase
a.c. electric power grid through electromagnetic power switches with
adequate protection. It is so convenient.
6 Q; y9 p+ B/ z1 T% PSmall power induction motors, in most home appliances, are fed from the
& ^3 Q/ q& k6 }- E. Olocal single phase a.c. power grids. Induction motors are rugged and have
2 X# f4 }3 n* u' Nmoderate costs, explaining their popularity.
In developed countries today there are more than 3 kW of electric motors
( s; n& A8 p; K2 N8 W- x6 J; x8 hper person, today and most of it is from induction motors.
5 |) x' J2 `  m- N$ EWhile most induction motors are still fed from three-phase or single-phase
power grids, some are supplied through frequency changers (or power
electronics converters) to provide variable speed.
% N, c' F' N# T  ~8 r3 zIn developed countries, 10% of all induction motor power is converted in
7 S2 {( T/ I0 ]% n+ x4 X) o! Lvariable speed drives applications. The annual growth rate of variable speed
/ \9 o6 ]3 p0 x  n" K8 C7 q( Ydrives has been 9% in the last decade while the electric motor markets showed
; @: U8 ~+ \* Ian average annual growth rate of 4% in the same time.
Variable speed drives with induction motors are used in transportation,
pumps, compressors, ventilators, machine tools, robotics, hybrid or electric
vehicles, washing machines, etc.
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