EASA Motor Repair Slides [PDF]

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MDM Webcast May 25, 2011 2 - 3 p.m. Eastern



Motor Management Truths and Consequences: Understanding Electric Motor Rewinds and Efficiency



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Today’s Web cast • MDM and motor management strategies • • • •



Overview of motor repair and rewinds Mechanical rebuilding and rewinding Effects of repair and rewind on efficiency Resources and considerations



• Questions and Answers 3



MDM Sponsors Efficiency Programs • Alliant Energy • BC Hydro • Efficiency Vermont • Long Island Power Authority (LIPA) • MidAmerican Energy Company • National Grid USA • New Jersey Office of Clean Energy • New York Power Authority (NYPA) • NYSERDA • Northwest Energy Efficiency Alliance • Pacific Gas & Electric (PG&E) • Southern California Edison (SCE) • Tennessee Valley Authority (TVA) • Xcel Energy



Manufacturers – Motor & Drive • ABB • Danfoss • GE Energy Motors • TECO-Westinghouse Motor Company Other Organizations • Advanced Energy • Copper Development Association, Inc. (CDA) • Electrical Apparatus Service Association (EASA)



For more information, visit: http://www.motorsmatter.org/sponsors/



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Motor Decisions MatterSM Managed by CEE, a national awareness campaign to:



• Encourage sound motor management, including – Demonstrate financial benefits of life cycle cost analysis – Inform motor repair-replace decisions – Promote premium efficiency motors and best practice motor repair



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Effective Motor Management



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Motor Management Truths and Consequences: Understanding Electric Motor Rewinds and Efficiency



Tom Bishop, P.E. Electrical Apparatus Service Association, Inc. St. Louis, MO



Background: What is EASA • Electrical Apparatus Service Association • Trade association serving the electrical and • • • •



mechanical apparatus sales, service and repair industry Founded in 1933 More than 1,900 member firm locations worldwide; approximately 1,400 in the U.S. Supports its members with industry research, engineering services, and education Establishes industry standards and practices 8



Motor Repair and Rewind Overview • All repairs include mechanical rebuilding Some repairs require rewinding



• Repair truths and consequences • Key resources • Key factors that influence the repair decision



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Rewind versus All Repairs



10 Source: A Survey of Faults ..., IEEE Petroleum and Chemical Industry Paper No. PCIC-94-01.



Mechanical Rebuilding • Consists of Test and inspect Disassemble Cleaning/overhaul Measurement of mechanical fits Bearing replacement Restore mechanical fits and components Assemble and test



• Most repairs are mechanical rebuilding without rewinding



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Mechanical Rebuilding • Test and inspect • Disassemble • Cleaning/overhaul



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Mechanical Rebuilding • Measurement of fits • Bearing replacement • Restore mechanical fits and components



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Mechanical Rebuilding • Assemble and test • Final step after mechanical repair with or without rewind



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Rewinding • A sub-process to mechanical rebuilding • Random (round wire) windings • Form coil windings



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Rewinding • Resin treatment and curing



• Electrical testing



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Effect of Repair and Rewind on Efficiency • Truths



• and Consequences



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Truths • Rewinding using best practices Maintains efficiency May improve efficiency



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Truths • Maintain efficiency by Copy-rewind or winding pattern improvement Using same winding coil wire area Using same average length of turns



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Truths • Opportunity to improve efficiency by



Wire Wire Size: Size:



AWG 17



Bare BareDiameter Diameter == .0453 .0453



Wire Size:



AWG 16



Bare Diameter = .0508



Using larger winding coil wire area Reducing average length of turns Average length of turn = (2 x Ls) + (4 x Lc) 20



Truths • Efficiency does not change with subsequent rewinds Core losses do not increase Winding data rarely changes



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Truths • Repairing can restore: Reduction in efficiency due to prior repairs • Restoration associated with a rewind • Restoration associated with mechanical repair



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Truths • Repairing can restore: Reduction in efficiency due to damage from motor failure(s) • Associated with winding failure(s) • Associated with mechanical failure(s)



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Truths • Repairing can restore: Motors to like-new condition Sometimes even better than new



• Repairs can enhance suitability of motor for its application and environment 24



Consequences • Consequences of poor practice repairs: Reduced efficiency Reduced reliability



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Consequences • Reduction in efficiency can occur Core damage due to winding removal Not the only reason for reduction in efficiency during repair… 26



Consequences • Reduction in efficiency -- other factors Winding copper losses increased due to incorrect winding data or method Bearing friction losses increased due to incorrect bearings, fits, improper lubrication (I2R)



Wire Size:



AWG 16



Bare Diameter = .0508



Wire Size:



AWG 17



Bare Diameter = .0453



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Consequences • Consequences of best practice repairs: Efficiency maintained • Efficiency may be improved Reliability maintained • Reliability may be improved Motor description



Efficiency before rewind



Efficiency after rewind



Efficiency change



Comments



7.5hp 4 pole



83.2%



84.0%



+0.8%



concentric to lap 5 burnouts 1 rewind



100hp 4 pole



93.0%



93.6%



+0.6%



full to half slot lap



100hp 4 pole



93.0%



93.7%



+0.7%



3rd rewind



0.0%



full to half slot lap 1st and 2nd rewinds



150hp 2 pole



95.9%



Source: EASA/AEMT Motor Rewind Study, 2003



95.9%



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Key Resource Documents • ANSI/EASA AR100 2010 Recommended Practice for the Repair of Rotating Electrical Apparatus



• EASA/AEMT Rewind Study The Effect of Repair/Rewinding on Motor Efficiency



• EASA Tech Note 16 Guidelines for Maintaining Motor Efficiency During Rebuilding 29



ANSI/EASA AR100 • The American National Standard for repair of rotating electrical apparatus • Purpose: establish guidelines in each step of electrical apparatus rewinding and rebuilding • Concisely (22 pages) describes best practice repairs 30



ANSI/EASA AR100 Benefits • Provides guidance for service centers to perform best practice repairs • End users are assured that compliant repairs follow a national standard



• Results: Quality repairs Reliable repairs Efficiency maintained



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ANSI/EASA AR100 Content • General Identification, inspection, condition assessment, failure analysis, cleaning, transport



• Mechanical repair Shafts, bearings, lubrication 14 fit and tolerance tables



• Rewinding Core inspection, winding removal, winding specification



• Testing Insulation resistance, high-potential, surge, core laminations, no-load



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EASA/AEMT Rewind Study Key content: Good Practice Guide



• Inspection and dismantling • Testing • Winding removal and rewind • Mechanical repairs • Reassembling



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EASA/AEMT Rewind Study Key content: Good Practice Guide



• Lessons learned  Guide good practices  AR100 best practices • Provides source details for good/best practices Repair reference document for service centers Specification reference document for end users 34



EASA Tech Note 16* Key content



• Do’s include Core test before and after winding removal Repair or replace defective laminations Evaluate impact on efficiency if winding design changes



• Don’ts include Overheat stator core/use open flame Short laminations when grinding/filing Increase winding resistance



* Guidelines for Maintaining Motor Efficiency During Rebuilding 35



Key factors in repair or rewind decision • Horsepower rating Economic evaluation



• Motor type/features Availability of new



• Maintenance history Evaluate reliability



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Questions?



Thank You! www.easa.com 37



Contact Information • Motor Decisions Matter Campaign – www.motorsmatter.org – Email: [email protected] – Sign up for E-Newsletter



• MDM Events Calendar – www.motorsmatter.org/events/calendar.asp – Will include slides from today’s webcast



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