Presented by Shermco Industries
1
Motor Efficiency and
Legislation
Electric Motor Applications
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• Introduction
• NEMA
• Motor Efficiency
• Legislation
• Motor Efficiency Program
– Quality of Power
– Maintenance
– Repair, Recondition, Rewinding
• Summary
Topics
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• Motor Efficiency - Why is it Important
• It is estimated that 50% of all electrical energy
consumed in the United States is used by electric
motors
• Therefore improving and maintaining motor efficiency
will save energy and help in reducing plant operating
costs
Introduction
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• This presentation will cover different areas of concern
as it pertains to motor efficiency and recent
legislation that affects new motors
• Motor Efficiency Program (3 Main Areas)
– Quality of Power
• Check and test for power quality issues
– Maintenance
• It is important to maintain motors thru regular
Preventative/Predictive Maintenance Programs
– Repair, Recondition, Rewind of Motors
• Quality Process for control and materials
Introduction
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• When it comes to the Efficiency in a motor there are
many things to think about in making a decision.
– New
– Repair
– Maintenance
– Delivery
– Price and Payback
Introduction
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• The National Electrical Manufacturers
Association was established in 1926 to help promote
the standardization of electrical apparatus.
– The International Electrotechnical Commission (IEC):
The IEC primarily sets the standard for the rest of the world.
• The result of NEMA’s work is that you can expect
motors from different manufacturers that meet or
exceed the same minimum performance parameters
and for the most part be about the same size.
NEMA
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• The new NEMA Premium Efficiency Electric Motors
(600 Volts or Less) outlines the minimum
requirements for three-phase AC induction motors
applied to municipal and industrial applications for
operation on
– voltages 600 V or less
– rated 500 hp or less
– operating more than 2000 hours per year at >75% of
full-load.
– The cost of the motor is insignificant compared to the
cost of the electricity required to run the motor. If
operating 2000 hours or more per year, then it makes
sense to use only the most efficient motors available.
NEMA
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• The NEMA definition of energy efficiency is the ratio
of its useful power output (Mechanical) to its total
power input (Electrical)
• Improved designs, materials, and repair standards
enable energy-efficient motors to accomplish more
work per unit of electricity consumed.
• Energy-efficient motors also offer increased reliability– energy-efficient motors usually have higher service factors
– longer insulation and bearing lives
– lower waste heat output
– less vibration
NEMA
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• NEMA established the NEMA Premium Efficiency
Program for four main reasons:
– Electric motors have a significant impact on the total
energy operating cost for industrial, institutional and
commercial buildings.
– Electric motors vary in terms of energy efficiency. The
NEMA Premium program will assist purchasers identify
higher efficient motors that will save them money and
improve system reliability.
NEMA
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– NEMA Premium labeled electric motors will assist
users to optimize motor systems efficiency in light of
power supply and utility deregulation issues.
– NEMA Premium motors and optimized systems will
reduce electrical consumption thereby reducing
pollution associated with electrical power generation.
NEMA
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• The Institute of Electrical and Electronics
Engineers is the recognized testing lab for the
consistent measure of motor efficiency
– IEEE 112 Method B, is the preferred standard of
measurement that uses a dynamometer to measure motor
output under load
• The NEMA nameplate labeling system for design A
and B motors in the 1- to 500-hp range uses bands of
efficiency values based on IEEE 112 testing and they
are characterized by relatively low rotor winding
resistance.
– They are typically used in compressors, pumps, fans,
grinders, machine tools
Motor Efficiency
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What are the anticipated energy and environmental
impacts?
• Based on U.S. Department of Energy data, it is
estimated that the NEMA Premium motor program
would:
– save 5,800 gigawatts of electricity
– prevent the release of nearly 80 million metric tons of
carbon into the atmosphere over the next ten years.
– this is equivalent to keeping 16 million cars off the
road.
Motor Efficiency
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Motor Efficiency
• So what kind of improvement in efficiency should
you expect?
• Efficiency Expected in NEMA Motors
– Typical Single Phase 80.0%
– Premium Single Phase 86.5%
– Typical Three Phase 87.5%
– NEMA Premium® Three Phase 90.2%
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• Energy Independence and Security Act 2007– Act of Congress concerning the energy policy of the United States.
The Energy Independence and Security Act of 2007 (EISA) was
enacted by the 110th Congress and signed it into law on December
19, 2007 by President George W. Bush. The Law becomes
effective on December 19, 2010.
– The final law is 313 pages in length
• The stated purpose of the act is:– move the United States toward greater energy independence
– Security
– increase the production of clean renewable fuels
– protect consumers
– increase the efficiency of products, buildings, and vehicles,
– promote research on and deploy greenhouse gas capture and
storage options,
– improve the energy performance of the Federal Government, and
for other purposes
Legislation
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• One portion of EISA, in Title III, deals specifically with
electric motor efficiency, focusing on motors that
range from one to five hundred horsepower.
• The 2005 bill made the purchase of NEMA Premium
motors mandatory for government buildings in an
attempt to show leadership in saving energy.
• The 2007 bill raised the level of all product covered in
the original bill to the NEMA Premium levels with the
exception of Fire Pump motors (Due to low run
hours) Effective December 19, 2010
Legislation
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• You can Increase motor efficiency thru a Efficiency Improvement Program
– Identify and chart the motors presently in the system
• Gather nameplate information and obtain field
measurements (voltage, amperage, power factor,
operating speed) under typical operating conditions
• Initially focus on motors that exceed minimum size and
operating duration criteria
– Review the motors history
• Original Efficiency
• Repair History and Reliability
• HP vs. Load profile (Undersized /Oversized)
Motor Efficiency Program
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Motor Efficiency Program
• Conduct Efficient Motor Replacement Analysis
– Replace Immediately — Motors Offering Rapid Payback
through Energy Savings
– Replace at Time of Failure — Motors with Intermediate
Payback
– Leave Present Situation as is — Motors with Extended
Payback. These motors are already reasonable
– Use VFDs where applicable
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• Power Quality
– Address power quality problems to improve motor
reliability and efficiency. It is important to maintain
the correct voltage and phase balance to maintain
the rated motor efficiency
– Poor Quality Incoming Power
• Motor will perform improperly.
• Have less efficiencies
• Generate more heat
– Good Power Quality Incoming
• Balanced voltages and current are key to motor efficiency
and the operating life of the motor.
• Typically you want to monitor the voltage unbalances and
you want to monitor for harmonic distortions.
• The current levels you should also measure for unbalances,
harmonic distortions and levels as well.
Motor Efficiency ProgramPower Quality
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• Power Quality
– Power quality analysis coupled with Infrared Scans
help to meet the Preventative and Predictive
Maintenance needs
– Helps identify and eliminate current leaks, and
prevent harmonics in the electrical supply thru
testing
– Review the electrical system periodically, especially
before installing a new motor or after making
changes to the system and its loads
Motor Efficiency ProgramPower Quality
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• Power Quality
– There are 3 points to review with voltage
condition:
– Level, balance and distortion.
– Most voltage issues come from up stream.
And whatever problem you have with the
voltage bus, it will affect the entire voltage
bus.
– Generally this one motor that you are testing,
isn’t the only motor affected. Other motors
connected to that bus will be affected.
Motor Efficiency ProgramPower Quality
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• Power Quality
Identifies:
– Improper tap settings on supply
transformers
– Poorly distributed single phase loads
– Overloading (saturating) supply
transformers
– Missing or open power factor correction
capacitors.
– Voltage surge/sag
Motor Efficiency ProgramPower Quality
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• More Questions to ask to determine if you are
operating at the best efficiency possible in the plant.
– Are the transformers large enough?
– Are you overloading the service?
– Are you adding load to a bus in your plant?
• By monitoring your service or bus, you have
documented readings and know where any potential
issues may start.
Motor Efficiency ProgramPower Quality
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• On-Line and Off-Line Testing
– Performs necessary testing to determine the health of the
motor and the incoming power
– The continuous capture of all events enables users to develop
trends to maintain real-time operation parameters of the
equipment and power supply to improve reliability
– Problems can be detected before they cause severe damage
– Power monitoring has been designed to help identify the nature
and severity of power quality problems to prevent them from
recurring. Automated software pinpoints the location,
magnitude and duration of events to quickly remedy harmful
situations.
Motor Efficiency ProgramPower Quality
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Motor Efficiency ProgramPower Quality
• Online Testing• Power and current signature online motor testing programs allow
for the evaluation of motor circuit performance during operation and detect problems before they occur.
• Online is divided into Current Analysis and Voltage Analysis
• Current Analysis looks at
– the rotating components
– Loose or broken rotor bars
– cracked end rings
– rotor eccentricity
– misalignment and coupling/belt problems
• Voltage Analysis looks at
– Power quality issues like harmful harmonics
– voltage imbalances
– under/over-voltages
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• On line motor testing provides information about the
power condition, the load and the motor.
• Off line motor testing measures the integrity of the
motor’s insulation system and motor circuit
• Together they present a picture of the motors health
and provide information required to accurately
diagnose and predict imminent failures.
Motor Efficiency ProgramPower Quality
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• Power Quality
• Poorly performing Transformers
• Short, medium, long, range trip
settings
• Connection issues (Junction
Box, In motor)
• Lead Line Insulation
deterioration
• Turn-Turn, Phase-Phase, Coil-
Coil insulation weakness
• Ground Wall Insulation
– Weakness
– Dirt
Motor Efficiency ProgramPower Quality
– Moisture
– Dry Rotted, Brittle
– Cracks
• Motor Circuit
– Turn–Turn Shorts, Opens
– Reversed Coils
– Phase Unbalanced (turn count)
– Phase Unbalanced (wire size)
• Rotor
– Cracked Bars
– Poor Welds
– Broken Bars
– Eccentricity (Dynamic, Static)
Faults that Off Line and On Line tests will Identify
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• Loading Issues
– Over load
– Process
• Mechanical
– Bearing faults
– Misalignment
– Fan Unbalances
– Belt frequencies
– Worn Impellers
– Gear Mesh Frequencies
Motor Efficiency ProgramPower Quality
• VFD
– Power Quality
– Shorted IGBT’s
– Feed Back loop
– Process Information
– Tuning / Set up
• Soft Start
– Tuning / Set up
– Trouble shooting
Faults that Off Line and On Line tests will Identify
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• Voltage quality affects the temperature that a motor
works under. The worse the voltage quality, the
hotter the motor operates.
– “Rule of Thumb” motors operating at above rated
temperature; insulation life drops by half for each
10°C of over temperature.
* The ANSI/NFPA 70B Electrical Equipment
Maintenance Standard states that infrared
inspections of electrical equipment should be
performed annually.
Motor Efficiency ProgramPower Quality
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• How can an Infrared Thermography Inspection help?
• An infrared inspection can reveal hot spots in a
number of areas:
– Motors
– Low Voltage Switch Gear
– Power Distribution
– MCC
– Control Panels
• Infrared Scan can determine the motors temperature
to an accuracy of about 2°C
Motor Efficiency ProgramPower Quality
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• Preventative Maintenance
• Inspection and Cleaning
– Clean dirt from the frame and air passages of
the motor. Dirty motors run hot because the
dirt acts like a blanket of insulation and
plugged air passages reduce cooling air flow.
– Damp or water environments, the motor T-
box should be opened and checked for
deteriorating insulation and high resistance
connections.
– Check air flow, if blocked and air flow is weak,
remove the motor from service for
reconditioning
Motor Efficiency ProgramMaintenance
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Motor Efficiency ProgramMaintenance
• Preventive Maintenance (PM) is a scheduled
maintenance program used to prevent problems from
occurring between maintenance schedules
• Repairs are performed only when necessary.
• Predictive Maintenance (PdM) is a equipment
monitoring used to determine the health of the
equipment
• Used to predict when maintenance should be performed.
• The difference between Preventive and Predictive
• PM tasks are completed when the machines are shut down
• PdM activities are performed during machine operation
running in their normal production modes
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• Maintenance
– Laser Alignment
• Aligns motor mechanically to increase efficiency and
bearing wear
Motor Efficiency ProgramMaintenance
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• Vibration Analysis
• Collects data and trends into records
• Analyzes the data for predictability
• Not only indentifies mechanical issues, it can detect
electrical problems as well
• Electrical issues will show up as 2X line frequency or
7200 cycles per minute (cpm) at 60 Hz.
• What is Vibration Analysis?
• It is collection of data under operating conditions that
considers all contributing causes of possible vibration
Motor Efficiency ProgramMaintenance
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Motor Efficiency ProgramMaintenance
• If we could watch a vibrating object in slow motion, you
could see movements in different directions.
• Any vibration has two measurable quantities to
determine its vibration characteristics
– How far (amplitude or intensity),
– How fast (frequency) the object moves,
Representation of the Measures of Vibration
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• Amplitude and Frequency are two measurable
quantities to determine vibration
– For example a rotor exhibiting large amplitude peaks at
the rotating frequency (1X) indicates a vibration
problem, due most likely to rotor imbalance
– Amplitude is a measure of vibration severity
– Frequency is a measure of oscillation rate
• Frequency also indicates the source of the problem
• Together, Amplitude and Frequency of vibration
provide a basis for identifying the root cause of the
vibration
Motor Efficiency ProgramMaintenance
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Motor Efficiency ProgramMaintenance
• Vibration Analysis
• Interpreting the collected data determines the mechanical
condition of a machine, locate specific faults and provides
information for corrective action
• Vibration Analysis is usually done in two stages, first
evaluation, then corrective action due to the fact that
rebalancing or realignment require shutdown for time to
perform the required repairs.
• If you wish to have success in Vibration Analysis Program
you must take the time to understand how to collect
measurements correctly. Making good, consistent
measurements is the single most important step in good
vibration analysis.
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• What is A Spectrum?
• Another kind of display commonly used by vibration analysts is
the spectrum. A spectrum is a graphical display of the
frequencies at which a machine component is vibrating, together
with the amplitudes of the component at these frequencies. But
how can a single machine component be simultaneously
vibrating at more than one frequency?
• The answer lies in the fact that machine vibration, as opposed to
the simple oscillatory motion of a pendulum, does not usually
consist of just one simple vibratory motion. Usually, it consists of
many vibratory motions taking place simultaneously.
Motor Efficiency ProgramMaintenance
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• For example, the velocity spectrum of a vibrating bearing
usually shows that the bearing is vibrating at not just one
frequency but at various frequencies. Vibration at some
frequencies may be due to the movement of bearing elements,
at other frequencies due to the interaction of gear teeth, and at
yet other frequencies due to the rotation of motor windings.
• Because a spectrum shows the frequencies at which vibration
occurs, it is a very useful analytical tool. By studying the
individual frequencies at which a machine component vibrates,
as well as the amplitudes corresponding to those frequencies,
we can determine a great deal about the cause of the vibration
and the condition of the machine.
Motor Efficiency ProgramMaintenance
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Motor Efficiency ProgramMaintenance
• Spectrum Analysis Techniques
Identify what Type of Measurement Produced the FFT
Spectrum•Was it a displacement, velocity, acceleration measurement that produced the
spectrum?
• Where was the probe positioned; horizontal, vertical, axial, in the load zone?
• Are plots scaled consistently for easy comparison?
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Motor Efficiency ProgramMaintenance
• Spectrum Analysis Techniques (cont.)
Once Running Speed is Determined, Identify the Spectrum's Frequency
Ranges
• Identify any harmonics of running speed (1X, 2X, 3X, etc.).
• Identify bearing fault frequencies.
• Identify fan blade frequencies, if applicable.
• Identify number of gear teeth, if applicable.
• Identify pump impeller frequencies, if applicable.
1x
2x 3x
4x
Frequency
Am
pli
tud
e
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Motor Efficiency ProgramMaintenance
• Spectral Pattern Recognition
Frequency
Am
pli
tud
e
low frequency rotational events and harmonics
(i.e. imbalance, misalignment, looseness, etc.)
high frequency events
(i.e. bearing or gearmesh)< 1X
1x
2x 3x
4x
10x
Over time, the successful analyst recognizes spectral patterns as
representing specific machinery problems.
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• Vibration Analysis when used in conjunction with maintenance programs, help identify the need for corrective actions.
• Trending readings over time to help define the reliability of a motor.
• Plan maintenance operations and scheduled down time to make the necessary repairs through accurate planning, which produces more uptime and less downtime
Motor Efficiency ProgramMaintenance
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• Repair, Recondition, Rewinds
• Should I rewind a failed motor?
– Failed motors can usually be rewound, but keeping
efficiency in mind it may be better to replace it with a more
energy efficient motor.
– New energy-efficient models save energy and improve
reliability.
Motor Efficiency ProgramRepair, Recondition, Rewinds
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• Repair, Recondition, Rewinds
– Efficiency should be a major consideration whether
purchasing a new motor or rewinding a motor.
– Have motors rewound only at reliable repair shops that
use low temperature bake out ovens
– Perform and document a core loss test as part of their
rewind procedures.
– Use high quality materials
– Demonstrate and maintain a certified quality assurance
program based on EASA-Q or ISO-9000
• The following photos show what maintenance
can find:
Motor Efficiency ProgramRepair, Recondition, Rewinds
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• Cleaning?
Motor Efficiency Program Repair, Recondition, Rewinds
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• Prevented?
Motor Efficiency Program Repair, Recondition, Rewinds
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• Insulation Failure?
Motor Efficiency Program Repair, Recondition, Rewinds
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• Catastrophic Failure? Lamination Damage?
Motor Efficiency Program Repair, Recondition, Rewinds
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Laminations
• Steel laminations are coated to insulate from
adjacent laminations
– Reduces circulating current (iron losses)
– Thickness of laminations
• More laminations of thinner material reduces losses
(more laminations per inch)
• Better steel allows use of thicker laminations (less
laminations per inch)
• ―Balancing act‖ between lamination thickness and
coating to reduce losses.
Motor Efficiency Program Repair, Recondition, Rewinds
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• Laminations are a fundamental
importance in the design of an
electric motor. The selection of
the material is very important
to the operation design
features and efficiency in a
motor.
• Motor output, heat rise, weight,
and cost are only a few of the
characteristics which are
profoundly influenced by the
selection of core material.
Motor Efficiency Program Repair, Recondition, Rewinds
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• Types of Lamination
– C-3: Enamel or varnish coating
which offers excellent insulation,
but parts so coated cannot be
annealed after stamping.
– C-5: An improved inorganic
coating similar to C-4 but with
significantly higher resistance. It
withstands annealing well in most
cases. This is probably the best
choice for most performance
sensitive applications. The main
drawback to C-5 is an increase in
tool wear due to abrasiveness.
Motor Efficiency Program Repair, Recondition, Rewinds
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Burning
• Burning out the winding shall be burned out in a
controlled temperature burnout oven
– The stator temperature is monitored so the core
temperature is limited by means of fuel control and
supplementary (water spray) cooling to 360°C (680°F)
for organic (C3) or 400°C (750°F) for inorganic (C5)
inter laminar insulation.
– It is acceptable to cold or chemically strip windings
provided the lamination is not exposed to an open
flame and the laminations are not flared.
Motor Efficiency Program Repair, Recondition, Rewinds
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Laminations
• Lamination damage due to coil cutoff and removal.
– All obvious iron damage and significant frame damage,
plus any defects indicated by a core loss test, shall be
corrected.
– Grinding of the lamination is not permitted, however
limited de-burring is acceptable. Removal of individual
lamination(s) is not permitted. However, restacking part
or all of the assembly with the same number of de-
burred laminations that have the same material
composition, dimensions, and inter laminar insulation
characteristics as the original lamination assembly is
permitted.
Motor Efficiency Program Repair, Recondition, Rewinds
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• Thermal image of core test showing hot spot near
core end
Motor Efficiency Program Repair, Recondition, Rewinds
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• Coating may be damaged during improperly
performed rewind
• Increased iron losses
• Lower efficiency
• Hotter operation
Motor Efficiency Program Repair, Recondition, Rewinds
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Rewind
• Points to ensure efficiency is maintained
– Winding Data shall be recorded so as to permit
replicating precisely the original configuration.
– Core Loss test shall be done on all stators both before
and after stripping and iron repair
• Check for damaged inter laminar insulation. The tests
shall be done at a flux density of 85,000 lines per square
inch rms. Exciting current and watts loss shall be
recorded each time, as well as a physical check carried
out for hot spots
Motor Efficiency Program Repair, Recondition, Rewinds
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Summary
• In summary, improved design, materials, and
manufacturing techniques enable energy-efficient
motors to accomplish more work per unit of electricity
consumed.
• They also offer other benefits because they are
constructed with improved materials, which increase
reliability.
• Improving and maintaining motor efficiency will save
energy and help in reducing plant operating costs
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Summary
• New legislation has been enacted to move the United
States toward greater energy independence, security
and increase the production of clean renewable fuels
• Starting a motor efficiency program will identify
motors for replacement due to inadequate efficiency
• Remember efficiency should be a major
consideration whether purchasing a new motor or
rewinding a motor.
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Summary
• We have also learned that energy efficiency can be
improved thru power quality studies.
– Incoming Power is correct and balanced
– Perform On and Off-Line Testing as a scheduled
practice for maintaining motor maintenance
• Making sure the equipment we have now is operating
as efficiently as possible thru maintenance practices
should be our first goal
– Perform PM (Predictive Maintenance) on motors
– Perform electrical testing on motors for status
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Summary
• If you choose to rewind a motor make sure it is a reliable
repair shop that uses low temperature bake out ovens
and documents the core loss test as part of their rewind
procedures as per the EASA Rewind Spec.
• Make sure they use high quality materials and maintain
a certified quality assurance program based on EASA-Q
or ISO-9000
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• National Electrical Manufacturers Association
• - Institute of Electrical and Electronics Engineers
• EASA - Electrical Apparatus Service Association
• Baker Test Equipment
• Baldor and WEG Motors
Organizations
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• NEMA defines, in NEMA MG 1-19 9 3 motor designs
dependent upon motor torque during various
operating stages:– Design A: H as a high starting current (not restricted), variable
locked-rotor torque, high break down torque, and less than 5 %
slip.
– Design B: Known as "general purpose" motors, have medium
starting currents (50 0 -8 0 0 % of full load nameplate), a
medium locked rotor torque, a medium breakdown torque, and less
than 5 % slip.
– Design C: Has a medium starting current, high locked rotor torque
(2 0 0 - 250 % of full load), low breakdown torque (19 0 – 2 0 0
% of full load), and less than 5 % slip.
– Design D: Has a medium starting current, the highest locked rotor
torque (27 5 % of full load), no defined breakdown torque, and
greater than 5 % slip.
Notes on NEMA