Motor Efficiency and Legislation -...

Presented by Shermco Industries

1

Motor Efficiency and

Legislation

Electric Motor Applications

Presented by Shermco IndustriesPresented by Shermco Industries 2

• Introduction

• NEMA

• Motor Efficiency

• Legislation

• Motor Efficiency Program

– Quality of Power

– Maintenance

– Repair, Recondition, Rewinding

• Summary

Topics


• 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


• 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


• 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


• 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


• 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


• 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


• 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


– 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


• 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


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


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%


• 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


• 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


• 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


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


• 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


• 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



• 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.



• 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



• 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.



• 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.




• 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


• 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.



• 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


– 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


• Loading Issues

– Over load

– Process

• Mechanical

– Bearing faults

– Misalignment

– Fan Unbalances

– Belt frequencies

– Worn Impellers

– Gear Mesh Frequencies


• 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


• 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.



• 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



• 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

Presented by Shermco Industries


• 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


• Maintenance

– Laser Alignment

• Aligns motor mechanically to increase efficiency and

bearing wear



• 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




• 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


• 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




• 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.


• 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.



• 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.




• 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?



• 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



• 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.


• 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



• 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


• 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


• Cleaning?

Motor Efficiency Program Repair, Recondition, Rewinds


• Prevented?



• Insulation Failure?



• Catastrophic Failure? Lamination Damage?



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.



• 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.



• 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.



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.



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.



• Thermal image of core test showing hot spot near

core end



• Coating may be damaged during improperly

performed rewind

• Increased iron losses

• Lower efficiency

• Hotter operation



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



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


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.


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


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


• National Electrical Manufacturers Association

• - Institute of Electrical and Electronics Engineers

• EASA - Electrical Apparatus Service Association

• Baker Test Equipment

• Baldor and WEG Motors

Organizations


• 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

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