whymotorsfail-app01

7/27/2019 whymotorsfail-app01

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Motor Repair Guidelines

Why do Motors Fail?

Repair vs. Replacement

Maintaining Reliability & Efficiency


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Why do Motors Fail? Failed in service

Motor stored in preparation for service

Regularly scheduled maintenance Predictive maintenance testing reveals potential

concern regarding reliability

Motor requires upgrading

Modifications or addition of accessoriesfor new process

Failed or damaged accessories, i.e. brakes,tachs, encoders, thermal devices


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Why do Motors Fail?Motors don't fail just because of age or operatinghours. Typical failures are caused by:

Heat Power Supply Anomalies Humidity Contamination Improper Lubrication

Unusual Mechanical Loads

Motors have survived for several hundredthousand operating hours when thesestresses have been minimized.


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Common Causes For Motor Failures

Failure distribution statistics, like thesefrom IEEE Petro-Chemical Paper PCIC-94-01, are helpful, but still necessary toconduct a thorough root cause analysiswhen determining modes of failure.


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Why do motors fail?HeatTemperatures over the design rating take their toll in various ways.Electrical insulation deteriorates at a rate that may double for every10 C. Excessive temperature also causes separation of greases andbreakdowns of oils causing bearing failure.

Primary causes of overheating are:

Overloading

Too frequent starts (NEMA recommends two cold starts orone hot start per hour)

High ambient temperatures (NEMA typical design is 40 C)

Low or unbalanced voltages

High altitude operation

Inadequate ventilation i.e. damaged cooling fan,contaminated motor


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Why do Motors Fail?Power Supply Anomalies

Ideal power is a perfect sine wave on each phase at the motor's ratedvoltage & frequency-rarely achieved. The following problems appear.

Harmonics: Cause overheating and decreased efficiency.

Overvoltage: At moderate levels is usually not damaging, but canreduce efficiency and power factor. (NEMA limit 110%)

Under-voltage: Increases current and causes overheating and

reduced efficiency in fully loaded motors. It is relatively harmless inunder-loaded motors. (NEMA limit 90% of rated).

Voltage unbalance: Causes overheating and reduced efficiency.Unbalance greater than 1% requires motor de-rating and motorsshould never be powered by a system with more than5% unbalance.


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Why do Motors Fail?Power Supply Anomalies

Voltage spikes: Commonly caused by capacitor switching,lightning, or cable stranding waves from a variable frequency

drive (VFD). These tend to cause turn-to-turn failures. Frequencies under 60 HZ from VFDs: The application

should be reviewed to insure motor is suitable for theapplication without installation of supplemental cooling.

Bearing damage from shaft currents: This usuallyoriginates from VFDs. Consult the drive provider, motormanufacturer, or L&S Electric for information on strategiessuch as an insulated bearing sleeve, electro-conductivegrease, or a shaft grounding system.


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Why do Motors Fail?HumidityHumidity becomes a problem when the motor isde-energized long enough to drop near the dew point

temperature. Moisture weakens the dielectric strength of electrical

varnish and other insulating materials Contributes to corrosion of bearings and other

mechanical components Moisture from the air can mix with certain

particulate contaminants to create highlyelectro-conductive solutions.

Insulation moisture can be significantly

reduced if the motor is kept warm.


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Why do Motors Fail?Humidity Control Strategies:

By heating or dehumidification, keep the environment ofunpowered motors below 80% relative humidity.

Specify new or rewound motors with heating elementsfor the windings and use these when the motor isunpowered.

Periodically rotate the shaft of stored motors to keep

lubricant on the bearing surfaces.


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Why do Motors Fail?

Abrasion

Corrosion

Overheating

ContaminationContamination cannot be completely excluded by total enclosureor even an explosion proof enclosure. Contamination destroys

motors in three ways:

Some airborne particulates are very abrasive. Motor coilsflex when in use and contamination with abrasive particleseat away the wire enamel. Some substances, such as saltor coal dust are electrically conductive. Heavy accumulation

of contaminants typically obstructs cooling passages.


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Why do Motors Fail?

Improper Lubrication

Unfortunately, there are more ways to get it wrong than right.One can over-lubricate as well as under-lubricate.

Grease itself introduces contaminants into bearings if carefulcontrol is not practiced. Mixing greases with different bases

may cause grease constituents to separate and run out.

Different motors pose different requirements for the

introduction of lubricant and removal of old lubricant. Each individual application dictates the amount, type, and

frequency of lubrication required.

This is a complete subject in itself. L&S Electricprovides additional information for discussion.


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Why do Motors Fail?

Misaligned couplings

Over-tightened belt; or mis-alignment sheaves

Overly-compliant base or poor shimming of motor mounting feet

"Soft Foot," (i.e. motor feet) not in the same plane Dynamic imbalance of load or internal imbalance of motor rotor

Failure to bypass resonant speed point inVFD powered motors

Misapplication of bearings

Unusual Mechanical LoadsA variety of mechanical conditions can either overstress bearings,leading to early failure, or distort the motor frame causingasymmetric air gap, which in turn can cause vibration and bearing

failure or winding overheating. Conditions to avoid are:


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Repair vs. Replacement

Difference in cost of repair vs. new purchase

Difference in efficiency of existing and proposed new motor

Availability of a new motor

Lifetime discounted cost of electric energy for each scenario Possible mounting modifications

Cost in downtime and repairs from a possibleearly failure in either scenario

Simple answer in principle. Rewind or otherwise repair a motorwhen cheaper than buying a new motor. Implementing this is alittle more difficult because you need to consider the total costof ownership. Ideally you have to consider:


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Maintaining Reliability

& EfficiencyTo help assure a quality repair, you should:

Evaluate prospective motorrepair service providers

Don't pressure the providerfor unrealistic turnaround time

Clearly communicate your

requirements to the provider


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Evaluate Repair Providers

Look for indicators of a quality control program, such asevidence of participation in an ISO 9000 program,membership in EASA, & participation in EASAQ program.

Inquire about staff morale, training, turnover, etc. Determine whether the service center has sufficient facilities &

materials to handle the size & type of motors you send them.

Make an point to spend time evaluating each potentialprovider's service center.


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Note what test equipment the service center owns androutinely uses to verify successful repair. Examples: Core loss tester Surge comparison tester Voltage regulated power supply for

running at rated voltage Vibration testing equipment

Ask to see record-keeping system that the service centermaintains for repaired motors

Inquire about method of insulation removal, burnoff,mechanical pulling, etc.

For burn off, ask about methods for preventing flames or hotspots &ensuring uniform temperature when roasting multiple motors

Take note of the overall cleanliness of the service center

Evaluate Repair Providers


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L&S Electric Provides

Formal quality assurance program

Superior repair capabilities

Multiple repair service centers

Distribution of a wide variety of motors and electrical products

A diverse offering of products and services


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Quality Management

All operations certified to ISO 9001-2008

Dedicated Quality Assurance Manager

Standards consistent at all facilities

Documented work procedures calibration program


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Repair Warranty Rate


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Minneapolis Service Center


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2003 Established L&S Minneapolis Power ServicesDivision in Ham Lake

2004AcquiredAntec Motor Service, Mounds View 2005AcquiredAdvanced Motor Services, Minneapolis

2006 Service center expanded to nearly 55,000 squarefeet. Combined all three L&S Minneapolis locations in one

centralized location


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Motor Repair Productive Area: 35,000 sq. ft.

Power Services Productive Area: 2,560 sq. ft.

Warehouse: 6,000 sq. ft.

42' H Ceiling High Bay


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Shop Capabilities

Crane Capacity

High Bay 25 ton with 10 ton rider

High Bay/Low Bay work stations with15 jib cranes 16 foot - 2 ton cap

Middle Bay - 20 & 10 ton bridge cranes

East Bay - 15, 10, & 5 ton bridge cranes

West Bay - 15 & 10 ton bridge cranes


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Shop Capabilities

Phenix High Voltage Test Panel

1500 KVA

0-13.8 KV AC

0-750 Volts DC


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Shop Capabilities

Large Burn off Oven: 120" W 192" L 162" H


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Shop Capabilities

Large VPI System: 120" Diameter, 120" Deep,Von Roll 74035, Epoxy Varnish


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Shop Capabilities

Core Loss Tester 25 kVA Lexeco; 10 kVA Lexeco

Dynamic Balance Stands 5,000 lb, 10,000 lb, & 25,000 lb. Capacity

VPI System 120" Diameter 120" Deep w/ shaft well

Resin: Von Roll 74035 Epoxy

Varnish Dip Tank 52" W 48" H 48" D. Resin: Von Roll 716C Polyester

Epoxylite Trickle System: Two-part epoxy resin


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Shop Capabilities

Lathes Monarch 60" Swing, 212" L // Monarch 18" Swing, 60" L 2- LeBlond 24" Swing, 72" L // LeBlond Gap Bed 18 -30" Swing, 108"

Bridgeport Vertical Mill Hydraulic Presses

Horizontal - 600 ton, 72" Swing, 204" Length // Vertical 100 ton

Horizontal Pullers 50 ton, 40" reach // 50 ton, 38" reach // 20 ton, 28" reach

Welders MIG, TIG, & Wire Feed // Steel & Aluminum

Hot Metal Spray Eutectic Castolin TeroDyne F4901 gun with Metco 452 powder


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Other Shop Equipment

Paint Booth 16' W 8" D 10' H

Stripping Booth

Steam Cleaning Booth 20' W 18' D

Cryogenic (dry ice) Cleaning Machine Fork Lifts

(5) 8,000 lb. max capacity

Fleet

(2) Ford F550: 10,000 lb. capacity Nissan UD: 13,000 lb. capacity

International F8100: 26,000 lb. capacity

Chevrolet 2500HD Pickup

Ford Ranger Pickup


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Motor & Generator Repair

The Midwest's largest & most complete facilities

Capability to repair fractional through 10,000 HP

150 dedicated motor repair technicians

AC/DC, synchronous,& wound rotor

Field repair team

Rail equipment repair

Pump repair

Gearbox repair

Blower repair UL-Approved for repairing

explosion-proof motors


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Corporate Repair Capability

Complete calibration programs and documented workinstructions at all locations

Capability to repair fractional through 15,000 HP 6 VPI systems

Redundant capability at all locations

Winding, Machining, Balancing, & Testing


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Locations

Duluth

Menominee

Sturtevant

Minneapolis

AppletonWisconsinRapids

Montreal

Wausau

(3)


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L&S Facilities

Schofield, WI Corporate headquarters

Large motor & generator repair

Locomotive equipment repair

Sturtevant, WI

Serving customers in Wisconsin,Illinois, and Indiana

Motor repair

Reliability services

Rothschild, WI Motor repair

Central distribution warehouse

Reliability & Power Services

Appleton, WI Serving customers in eastern WI

Motor repair

Power & Reliability Services


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L&S Facilities

Menominee, MI

Serving customers in northeastWisconsin & eastern Upper Michigan

Motor repair through 3000 HP

New motor inventory through 200 HP

Duluth, MN Serving customers in NW

Wisconsin & Northern Minnesota

Motor inventory through 200 HP

Power & ReliabilityServices

Engineering Engineered Systems

Hydroelectric automation

Steam Turbine automation Panel manufacturing facility


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Suppliers Marathon Electric

Baldor/Reliance Electric

Yaskawa

Emerson

Teco/Westinghouse

General Electric

Lafert

Cutler-Hammer

ABB

AEGIS

Grove Gear

Danaher

Overly Hautz

InPro Seal

Baumuller


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Vendor Recognition

Marathon Electric's Largest Distributor

Yaskawa's Electric's Largest NA Distributor

Baldor / Reliance's 5 Star & CSP Designation

General Electric flagship distributor

Lafert's Top 5 Distributor List

Over $20 million in annual motor sales

Start-up & warranty service for most major suppliers


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Value We Offer

Capabilities to service all types and sizes of electricmotors, reducers, and pumps

A network of repair service centers

Ready access to sales & repair support

24/7/365 availability

Predictive and preventative services

ISO certified Quality Management System

Engineering & technical support

Free freight on our normal weekly routes

Warranty service for our suppliers


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L&S Electric: we continually work

hard to keep you running!

Thank you for your attention.

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