Download ENERGY EFFICIENT INDUCTION MOTORS

ENERGY EFFICIENT
INDUCTION MOTORS
By
JINTU GEORGE
Edited By
Sarath S Nair
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contents
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Introduction
Energy efficient motor
Specification of eem
Motor losses & reduction method
Benefits of implementing eem
Equivalent circuit
Experimental setup
Operating & performance characteristic
Eem in Indian scenario
Advantages
Application
conclusion
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Introduction
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A large fraction of electrical energy consumed in many
facilities is used to run electric motors. Nationally,
motor driven systems account for about 57% of all
electrical energy use.
The electric motor manufacturers are seeking methods
for improving the motor efficiencies, which resulted in
a new generation of electric motors that are known as
energy efficient motors.
This paper deals with energy conservation by installing
energy efficient motor (EEM) instead of standard
efficiency motor.
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Energy efficient motors
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It produces same shaft output power but uses less
electrical input power than a standard efficiency
motor.
Standard motor generally competes on price, not
efficiency, but EEM competes on efficiency, not
price.
Both single phase and three-phase motors available.
EEM are higher quality motors with longer warranty.
20 year life span
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Eem specifications
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to make it much easier for purchasers to identify energy
efficient motors on the market.
motor efficiency classification labels – Eff1, Eff2 & Eff3.
The programme was implemented by a voluntary agreement
between the Commission and the motor manufacturers to
reduce sales of Eff3 motors by half.
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Motor losses & reduction
Techniques
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Core loss represents energy required to magnetize the
core material (hysteresis) and includes losses due to
creation of eddy currents that flow in the core.
Windage and friction losses occur due to bearing
friction and air resistance.
Stator losses appear as heating due to current flow (I)
through the resistance (R) of the stator winding. This
is commonly referred to as an I2R loss.
Rotor losses appear as I2R heating in the rotor
winding.
Stray load losses are the result of leakage fluxes
induced by load currents.
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High efficiency motor design
Improved steel:
 Thinner laminations:
 Increasing conductor's volume:
 Modified slot design:
 Narrowing airgap:
 Improved rotor insulation:
 More efficient fan design:
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Benefits of implementing eem
systems
Electricity savings potential
 Environmental benefits
 Micro economical benefits
 Macro economical benefits
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Induction motor
equivalent circuits in d-q
coordinates
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Experimental setup
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Differerent tests for analysing
the performance
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a) Temperature test: The motor is loaded and
allowed to run until its temperature stabilizes.
The temperature and winding resistances are
recorded.
b) Load test: The motor is loaded at six different
loading points ranging from 25%-150% of rated
load. The stator and rotor copper losses are
calculated from this.
c) No-load test: The motor is run at no-load with
a varying supply. The friction & windage and
core losses are calculated
voltage between 125%
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to 20% of rated voltage from this.
Operating and performance
characteristics of sm& eem
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Constructional features of eef
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rotor design
- One major consideration in the design of high efficiency
induction motors is to reduce rotor resistance.
-efficiency can be achieved by substituting Aluminum
with copper.
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Energy Efficient Machine
Design by Proper Selection of
Core Material
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core loss in a machine is around 30~ 50% of the
total losses.
reduction of core material thickness and stress
relief annealing of the core improved machine
efficiency .
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Efficiency Improvement by
Insertion of Superconducting
Materials
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High temperature superconductors (HTS), which
offered the advantage of cooling via liquid nitrogen
instead of liquid helium.
complete elimination of refrigerator power
consumption would only show an improvement in
machine efficiency of ~0.02% for a 300 MVA rating.
Of more importance than the ef ficiency
improvement is that use of a liquid nitrogen ambient
would lead to reduced capital costs for the
refrigeration plant and reduce the complexity of the
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cryogenic design.
Rotor with two end rings
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Power factor improvement in
IM
Installing external capacitor
 Avoid operation of equipment above its
rated speed
 Replacement of SM with EEF.
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How energy efficient motor
differ from standard
motor ???...
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Higher quality and thinner steel laminations in
the stator
More copper in the windings
Smaller air gap between the rotor and stator
Reduced fan losses
Closer machining tolerances
Generally, they cost 15 to 30 percent more than
standard motors, depending on the specific
motor, manufacturer,www.technologyfuturae.com
and market competition
Eem recognition in indian
scenario
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Siemens India awarded prestigious “BEE
Star” rating for their energy-efficient motors
Siemens motors help
customers minimize their
energy consumption
in production, thus
significantly reducing their
operating costs and the cost
of ownership and bringing
about a significant boost to www.technologyfuturae.com
productivity.
Advantages:
- The EEM has a greater efficiency than a
standard motors; therefore they have less
operating costs.
 - EEM has a lower slip so they have a
higher speed than standard motors.
 - EEM can reduce maintenance costs and
improve operations in industry due to
robustness and reliability.
 - Increasing the productivity.
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Summary
Energy efficient motors, their specifications
are discussed.
 Constructional difference from standard
motor & the method of achieving high
efficiency is also discussed
 Different test methods, operating &
performance characteristics according to the
test result are also discussed
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References
[1] “Understanding Energy Efficiency Motors”, Electrical Apparatus
Service Association (EASA), pp. 12-14.
[2] D.G. Walters, I.J. Williams, D.C. Jackson, B. Hansen “The case for
a new generation of high efficiency motors – Some problems and
solutions”, Electrical Machines and Drives,11-13 Sept. 1995,
Conference Publication No. 412, IEE 1995.
[3] "Understanding high efficiency motors," Published by copper
development centre, 2001
[4] J. Andreas, Energy Efficient Electric Motors: Selection and
Application, Marcel Deker, 1992.
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