OCTOBER 2014 NIPSCO ENERGY SYMPOSIUM MANAGING ELECTRIC MOTORS FOR RELIABLE SERVICE Presented by: Todd A. Hatfield and Mark S. Hatfield of: HECO Inc. Industrial Service Groups of Kalamazoo Michigan HECO Introduction Who is HECO? HECO is an Electric Motors & Performance Systems Company We specialize in custom systems That optimize the performance of Electric motor driven powertrains. How do we do this? • Electric Motor & Generator Repair • • • Specification based Procurement from fractional through 15,000HP+ Mfg’s such as ABB/Baldor, Siemens, TECO-WH, WEG, GE, Etc. Predictive Services • • 110v AC through 13,800v AC & Up to 750v DC Electric Motor & Control Sales • • • Repair, Engineering, & Testing from ¼ HP through 25,000+ HP ISO Certified Vibration Analysts (through Cat IV), Tribology, Thermography, Ultrasonic Analysis, Wireless Condition Monitoring Electric Motor Control Services • Control Retrofitting, DC to AC Conversions, VFD Programming & Start-Up, Control Troubleshooting, etc. History • • • • • HECO was founded in 1959 Started first Motor Management Program in 1984 with Kalamazoo, MI area General Motors plants. From 1968 to 1992 we grew from a 8,125 Sq. Ft facility to the present 65,000 Sq. Ft. Opened our 176,000 Sq. Ft Warehouse in Hammond, IN in 1995 In 2013 we acquired Predictive Maintenance Services Inc. and Formed HECO Predictive Service Group. Testing a 4000hp, 4000V Siemens motor on our 13.8kv, 4000KVA, 100 ton weight limit test stand Machining the shaft on a 9000HP remanufactured rotor on our 79” Swing x 20’ long lathe Balancing a 1750KW Armature on our 30,000lbs computerized dynamic balance stand Moving a 3000HP, 514RPM Vertical Motor after assembly Lifting a 13.8kV Generator off of our truck for repair Electrical testing re-built field frames Unloading 3 Hydro-Generators for complete remanufacturing Loading a 1250KW armature into our 17’ tall curing/bake oven Introduction to: Managing Electric Motors for Reliable Service In this seminar we will discuss the “industry workhorse”, the AC Induction Motor; and how it works; the various component parts and how these components can vary in design and shape to produce a multitude of specific designs that work for a variety of applications. We will also talk about operating abuse and what to avoid to improve reliability. Finally, we will discuss a systematic 12 step approach to Managing Electric Motors for Reliable Service. How an AC Induction Motor works Basic AC Motor Operation An AC motor has two basic electrical parts: a "stator" and a "rotor“. The stator is in the stationary electrical part. It consists of a group of individual electromagnetic coils arranged in such a way that they form a hollow cylinder. The term, "stator" is derived from the word stationary. The rotor is the rotating electrical component. It consists of a group of electro-magnets arranged around a cylinder. The rotor, is located inside the stator and is mounted on the motor's shaft. The term "rotor" is derived from the word rotating. The objective is to make the rotor rotate which in turn will rotate the motor shaft. This rotation occurs because unlike magnetic poles attract to each other and like poles repel. Basic electrical components of an AC motor. If we progressively change the polarity of the stator poles in such a way that their combined magnetic field rotates, then the rotor will follow and rotate with the magnetic field of the stator. Alternating Current - AC The concept of alternating current came from Nichola Tesla back in the late 1800’s. The concept was to have current flowing in one direction through the conductor and then in the other direction. By doing this, you would have a positive (+) direction half the time and a negative (-) direction the other half. In the U.S.A. the current flow will repeat the positive and negative cycle 60 times per second. This 60 cycles per second is the frequency at which power is produced. One cycle per second is equal to one Hertz. Note: The strength of the magnetic field produced by an AC electro-magnetic coil increases and decreases with the increase and decrease of this alternating current flow. Visualization of AC. Current can be dangerous! Faradays Law of Electromagnetic Induction Three things must be present in order to produce electrical current: 1. Magnetic field 2. Conductor 3. Relative motion Conductor cuts lines of magnetic flux, a voltage is induced in the conductor This “rotating magnetic field” of the stator can be better understood by examining the Figure below. As shown, the stator has six magnetic poles and the rotor has two poles. At time 1, stator poles A-1 and C-2 are north poles and the opposite poles, A-2 and C-1, are south poles. The S-pole of the rotor is attracted by the two N-poles of the stator and the Npole of the rotor is attracted by the two south poles of the stator. At time 2, the polarity of the stator poles is changed so that now C-2 and B-1 are N-poles and C-1 and B-2 are S-poles. The rotor then is forced to rotate 60 degrees to line up with the stator poles as shown. At time 3, B-1 and A-2 are N. At time 4, A-2 and C-1 are N. As each change is made, the poles of the rotor are attracted by the opposite poles on the stator. Thus, as the magnetic field of the stator rotates, the rotor is forced to rotate with it. Three Phase Power 3 phase AC generators produce three separate current flows (phases) all superimposed on the same circuit. This is referred to as three-phase power. At any one instant, however, the direction and intensity of each separate current flow are not the same as the other phases. (This is illustrated in the Figure below. The three separate phases (current flows) are labeled A, B and C.) A complete cycle takes one complete revolution of the generator or 360 electrical degrees. Note: each phase is displaced 120 degrees from the other two phases or 120 degrees out of phase. The pattern of the separate phases of threephase power. A B C “Rotating Magnetic Field” conceived by Nichola Tesla The basis for the three phase induction motor The basic Induction motor How voltage is induced in the rotor, resulting in current flow in the rotor bars. Motor Construction Three Phase Motor Construction Windings – Electromagnets Rotor bars Rotor Stator Stator Windings Enclosure Air Gap Stator Rotor Side View AC Motor Components Two Basic Parts of any AC Motor • • Stator contains windings mounted in frame of motor Rotor and Shaft rotating unit mounted on bearings and provides mechanical power Stator Rotor Shaft Rotors Rotor With an induction motor’s rotor, there is no connection to the power supply. As its name implies the rotor rotates from Induction resulting from the magnetic field of the stator. This induction is a natural phenomenon which happens when a conductor (aluminum or copper alloy) is moved through a magnetic field or when a magnetic field is moved past the conductor/bar. Construction of an AC induction rotor. ROTOR DESIGN - Cast vs. Bar Cast Rotor • Rotor Bars in Intimate Contact With Laminations (Excellent Heat Dissipation) • Wide Variety of Slot Shapes Possible for Various Speed/Torque Characteristics Bar Rotor • Rugged Construction • Repairable • Different Alloys , Different Speed/Torque Characteristics ROTOR DESIGNS Aluminum Rotor Copper Alloy Rotor Common types of aluminum rotors Common types of Copper alloy rotors Copper alloy rotor Fabricating a spider shaft assembly Bars are tightly inserted Bar Rotor Construction Steps Rotor slot shapes Stacked Rotor Laminations Bar Rotor Construction Steps Comparison of Cast Al vs. Cu Bar Rotors Characteristic: Cast Al CuBar Manufacturing Costs Low cost to build each High Tooling cost 55% only High cost to build each Low Tooling cost 100% to 5% Good Inertia of rotor Excellent (3X heat transfer) Low (20-30% lower) Size limitations Up to 5812 Frame 5000 Frame and up Casting PorosityPotential Repairable Yes No No Yes Conductivity Starting ability Good Stators Stators Laminated stator cores before rewinding GE 3500 HP Stator with windings Allis Chalmers 10,000 HP Stator STATOR WINDINGS Form Wound Siemens 4000HP Stator being rewound LOWER VOLTAGE STATOR WINDINGS Random Wound Questions? We all need a SHORT vacation sometimes! Bearing Selection Motor bearings are selected based on application requirements: Load Speed Temperature Environment Motor Bearing Types Depending on size, rotational speed, load, and other application requirements, (3) basic bearing designs are used: • Anti-friction (Ball, Roller, etc): • • • Used in large horsepower based on application Journal/Sleeve: • • Primarily used in NEMA size (integral horsepower) motors Used exclusively in medium to Large horsepower motors Tilting Pad (Kingsbury): • Used exclusively in large vertical motors Anti Friction Bearing Advantages Relatively low cost Simple design With stand long periods of non-use Multiple motor mounting positions Good for radial and axial loads Replacements easily obtained from multiple sources And Disadvantages Speed and shaft diameter limited Requires periodic re-lubrication Replacing bearings requires major motor disassembly Bearing life limited due to fatigue Ball Bearing Components Basically, all bearings consist of 4 parts: 1. Inner Ring/Race 2. Outer Ring/Race 3. Rolling Element 4. Retainer Understanding Motor Nameplates What the information really means Detailed Nameplate Information • The nameplate of a motor provides important information necessary for selection and application. Voltage and Amps AC motors are designed to operate at standard voltages and frequencies. This motor is designed for use on 460 VAC systems. Full-load current for this motor is 34.9 amps. Nameplates continued RPM • The nameplate speed (RPM), is where the motor develops rated horsepower at rated voltage and frequency. The base speed of this motor is 1765 RPM at 60 Hz. The synchronous speed of a 4-pole motor is 1800 RPM (@ 60 Hz). When fully loaded there will be 1.9% slip. If the connected equipment is operating at less than full load, the output speed (RPM) will be greater than nameplate. RPM = 120 x Hertz = 120 x 60 = 1800 rpm poles 4 % slip = Sync RPM – Full load RPM X 100 Sync RPM Motor Operating Speeds At 60 HZ At 50 HZ • # OF POLES SYNCHRONOUS SPEED (RPM) FULL LOAD SPEED(RPM) 2 3600 3550 4 1800 1750 6 1200 1150 # OF POLES SYNCHRONOUS SPEED (RPM) FULL LOAD SPEED(RPM) 2 3000 2958 4 1500 1458 6 1000 958 Mechanical speed tied to speed of rotating magnetic field in stator • • Synchronous Speed = 120 x Frequency/# Poles = (@ 60 Hz) 7200/# poles Rotor lags behind - difference called “Slip” “What is Slip?” • • • To produce torque in an induction motor, current must flow in the rotor. To produce current flow in the rotor, the rotor speed must be slightly slower than the synchronous speed. The difference between the synchronous speed and the rotor speed (rated speed) is called the slip. Flux Stator Slip Rotor Nameplate continued • Service Factor A motor designed to operate at its nameplate horsepower rating has a service factor of 1.0. This means the motor can operate at 100% of its rated horsepower. Some applications may require a motor to exceed the rated horsepower. In these cases a motor with a service factor of 1.15 can be specified. The service factor is a multiplier that may be applied to the rated power. A 1.15 service factor motor can be operated 15% higher than the motor’s nameplate horsepower. The 30 HP motor with a 1.15 service factor, for example can be operated at 34.5 HP. • It should be noted that any motor operating continuously at a service factor greater than 1 will have a reduced life expectancy compared to operating it at it’s rated horsepower. In addition, performance characteristics, such as full load RPM and full load current, will be affected. Nameplate continued • Class Insulation The National Electrical Manufacturers Association (NEMA) has established insulation classes to meet motor temperature requirements found in different operating environments. The four insulation classes are A, B, F, and H. Class F is commonly used. Class A is seldom used. Before a motor is started, its windings are at the temperature of the surrounding air. This is known as ambient temperature. NEMA has standardized on an ambient temperature of 40° C, or 104° F within a defined altitude range for all motor classes. Nameplate continued • • Temperature will rise in the motor as soon as it is started. Each insulation class has a specified allowable temperature rise. The combination of ambient temperature and allowed temperature rise equals the maximum winding temperature in a motor. A motor with Class F insulation, for example, has a maximum temperature rise of 105° C when operated at a 1.0 service factor. The maximum winding temperature is 145° C (40° ambient plus 105° rise). A margin is allowed to provide for a point at the center of the motor’s windings where the temperature is higher. This is referred to as the motor’s hot spot. The larger the temperature gap is between actual motor operating temperature and the motor insulation class, the longer the insulation life will be. Nameplate Continued • The operating temperature of a motor is important to efficient operation and long life. Operating a motor above the limits of the insulation class reduces the motor’s life expectancy. A 10° C increase in the operating temperature can decrease the motor’s insulation life expectancy as much as 50%. Ambient Most of the time, the ambient consists of the heat generated by the heating and cooling system around the motor (this would include changes in the weather). Many times there are other heat sources close to the motor that will have an effect on the surrounding ambient. These sources can include: 1. The bearing temperatures and lubrication system 2. Running the motor in a confined space without proper ventilation 3. Poor positioning of air duct openings such as weather protected motors 4. Coupling and belt losses 5. Heat from the driven equipment, piping, plumbing, and other machines in the area This table shows the effects to the insulation life when the allowed temperature rise of the stator windings is exceeded. Nameplate continued • Motor Design The National Electrical Manufacturers Association (NEMA) has established standards for motor construction and performance. NEMA design B motors are most commonly used. • Efficiency --- AC motor efficiency is expressed as a percentage. It is an indication of how much input electrical energy is converted to output mechanical energy. The nominal efficiency of this motor is 93.6%. The higher the percentage the more efficiently the motor converts the incoming electrical power to mechanical horsepower. A 30 HP motor with a 93.6% efficiency would consume less energy than a 30 HP motor with an efficiency rating of 83%. This can mean a significant savings in energy cost. Lower operating temperature, longer life, and lower noise levels are typical benefits of high efficiency motors. Nameplate continued Locked-Rotor kVA code Letter (L.R. KVA Code) A NEMA code letter (from A-V) which defines the Locked-Rotor kVA per-HP basis. This is used by the installer to determine the proper circuit protection rating. Replacing a motor with a higher locked rotor code may require additional electrical control equipment to handle the higher inrush currents. NOTE: It is important to pay attention to NEMA code letters, As the letter goes up the inrush current increases for a given design Efficiency AC motor efficiency is expressed as a percentage. It is an indication of how much input electrical energy is converted to output mechanical energy Motor-driven equipment “consumes” a certain percentage of power when driving a given load. This is defined as “Watt Losses”. Watt Losses Input Power (Watts) Load A-C Motor (Some power lost During conversion) (Output power 1 HP = 746 Watts) Calculation of energy efficiency Efficiency = (0.746 x HP Output ) KWatts Input = Input - Losses Input OPERATING CHARACTRISTICS Motor Electrical Characteristics • Torque Curves • NEMA Designs • Starting • Supply voltage considerations Typical Speed vs. Torque Curve Motor torque is defined at four points on a motor “Speed vs. Torque” curve and are: Definitions of Motor Torques ¼ Horsepower? • • • • Locked-rotor Torque of a motor is the minimum torque, which it will develop at rest for all angular positions of the rotor, with rated voltage applied at rated frequency. Pull-up Torque (Accelerating Torque) of an alternatingcurrent motor is the minimum torque developed by the motor during the period of acceleration from rest to the speed at which breakdown torque occurs. (CAN BECOME CRITICAL IN STARTING APPLICATIONS) Breakdown torque of a motor is the maximum torque which it will develop with rated voltage applied at rated frequency, without an abrupt drop in speed. Full-load torque of a motor is the torque necessary to produce its rated horsepower at full-load speed. Motor Designs • • The Material and Shape of the Rotor Bars Are the Main Factors in Obtaining Various Speed/Torque Curves NEMA Defines 4 Basic Types of Speed/Torque Characteristics for Induction Motors: • • • • • • DESIGN A DESIGN B DESIGN C DESIGN D The Stator Has Little to Do With the Shape of the Motors Speed vs. Torque Curve - Different Rotors Can Be Used With the Same Stator to Change the Characteristic Shape. Note: This only applies to NEMA frame motors, above NEMA frames, Induction motors are designed for the application and can have a variety of torque characteristics that are unique and not standardized. Comparison of NEMA Designs NEMA Design Characteristics Motor Starting Inrush Currents • • Locked Rotor Current typically 600-800% of full load Current and torque aren’t linear until near full load Never start a motor too quickly! Motor Starting Considerations • The motor torque vs. speed curve is usually provided at rated voltage. The torque and current of the motor will change with voltage. The relationship between torque and voltage is as follows: Torque Voltage2 • If voltage at the motor terminals is low, the torque produced by the motor will drop by approximately the square of the voltage. Therefore, a motor with 90% rated voltage at the terminals will have about 81% of peak torque. Since the motor has lower torque, acceleration time will increase. If the torque of the motor drops such that it is not greater than the torque required to accelerate the load, the motor will not reach rated speed. Current Voltage • • The current of the motor drops proportional to voltage. Therefore, a motor with 90% rated voltage has current reduced approximately 10% throughout the speed range. The acceleration time of the motor is dependent on many factors. The motor torque and inertia as well as the load torque vs. speed curve and inertia have to be known to determine acceleration time. The acceleration time of a motor can be calculated using the following equation. Acceleration Time = (WK²M + WK²L) x RPM 308 x Avg Accelerating Torque RPM = Change in speed in rpm. Average acceleration torque in lb.-ft. = (Average motor torque less average load torque from minimum to maximum speed) WHY CARE? • • • Motor could reach a stall condition Length of start time can exceed hot or cold start motor thermal limits and crack end ring brazing Could have been avoided with 80% voltage torque curve information Stall Condition THINGS THAT IMPACT MOTOR LIFE Examples of load differences The same motor but with a load that requires a higher pull up or accelerating torque…. This would cause a stall condition. The same motor but with a load that does not require higher torques to obtain full speed. Supply Voltage Considerations • • • Over voltage or under voltage can cause motors to draw more current Effect of voltage change Operating characteristic 90% voltage 110% voltage 120% voltage torque Decrease 19% Increase 21% Increase 44% Synchronous speed No change No change No change Percent slip Increase 23% Decrease 17% Decrease 30% Full-load speed Decrease 1% Increase 1% Increase 1% Starting current Decrease 10-12% Increase 10-12% Increase 25% Magnetic noise, any load Decrease slightly Increase slightly Noticeable increase Starting and maximum running NEMA standards allow + or - 10% voltage variation without degrading the life of the motor Frequency can vary + or - 5% without degrading the life of the motor per NEMA standards Phase Balance Example • • • • • • Phase Unbalance = 3% Temp. Increase = 2 (3)2 Temp. Increase = 18% A motor normally operating with a 750 C. rise will see an 18% increase in operating temperature. (75 x 1.18 = 850 C.) With 3% voltage unbalance, a motor can produce 90% of its rated horsepower without overheating. Operation of a motor when the unbalance exceeds 5% is not recommended. When unbalanced voltages exceed 5%, the temperature rise is so fast that protection by de-rating is not practical. Voltage phase unbalance is the most difficult to detect and therefore, often overlooked. Motor failures caused by voltage unbalance and are often misdiagnosed as being damaged by phase loss. What can happen when left undetected Voltage Unbalance = 236 – 228 X 100 = 3.5% 228 Temperature increase = 2x(Phase unbalance)² = 2(3.5)² = This will lead to a overheated phase and winding failure 24.5% increase in winding temp Phase Voltage Unbalance • • • Slight unbalance = large temp. rise. High current phase: % increased temp. = 2 (% voltage unbalance)2 • • NEMA recommends voltage unbalance not exceed 1%. Current unbalance will be 6 to 10 times voltage unbalance. High/Low Line Voltage • • Motors are designed to operate on a balanced voltage +/- 10% of nameplate voltage. Voltage variations have the effect of changing a motor’s rating by the square of the voltage variation. High/Low Line Voltage High/Low Voltage Example • A 10 hp. Motor operating with line voltage 10% below nameplate will have 8 hp. characteristics. • (90%)2 / 100 = 81% • 10 hp x .81 = 8 hp. • The motor will overheat trying to produce 10 hp. Motor Life • In general, we can say that a “quality” electric motor should have a designed life in excess of 20 years. • In reality, actual motor life in an industrial environment is probably closer to between 5 and 10 years. Temperature effect on motor life • • Insulation life • • • • • Heat is the #1 cause of reduced insulation life Winding insulation is rated according to it’s thermal capability For every 100 C above rated temperature cuts life by 50% For every 100 C below rated temperature, motor life increases by a multiple of 2 Common overheating sources beyond basic design • Overload • Inadequate ventilation • Dirt buildup • Phase unbalance • High/Low voltage Bearing life • • Bearing temperatures are typically 50-75% of winding temperature Temperature impact (+ 100 C = 50% life) Types of failures Other (12%) Motors fail for a variety of reasons. Rotor (10%) EPRI study of 6000 utility motors But, with proper maintenance, you can reduce or eliminate most causes. Bearings (41%) Stator (37%) Breakdown of motor component failures Operating Abuse • Induction motors will operate under the most adverse conditions. These adverse conditions are usually preventable, unfortunately a great majority of the time Failures are based on operating abuse by humans who do not fully understand the impact they have on the motor. Bearing failures (Equate to more than 40% - 50% of motor failures) • • Most bearing failures can be prevented as they mostly stem from too much or too little lubrication. Too much lubrication will force grease/oil into the motor and then the winding. This leads to pressure (increased friction) on the bearings that results in heat (Can also lead to winding contamination failure). Additional causes for bearing failures include: Coupling misalignment, Contamination from external environment (such as water, dirt, etc.), mixing incompatible greases and oils, motor mounting issues that cause a “soft – foot” condition leading to vibration, shaft circulating currents; caused by magnetic dissymmetry (inherent in larger motors approx. 800HP and up), VFD drives powering a motor with a chopped waveform and magnetism induced into the shaft or frame of a motor can also be a source Over lubricated Under lubricated Human error in too much and too little grease Broken Shaft Heat damage from failed bearing Excessive belt tension causing shaft and roller bearing failure Winding Failures (Contribute to approximately 30% to 37% of motor failures) • • Mechanical overload is the leading cause of winding failures. Operating a motor only 15% above rated load can reduce winding thermal life to one fourth of normal. A common misunderstanding is that motors can be continuously loaded into there service factor. The service factor is intended for short term, intermittent use. The solution to mechanical overload is simple, reduce the load to no more than the HP rating of the machine (Failures due to excessive heating in the winding). Starting and stopping a motor. The hardest condition on an electric motor is starting. When the power button is pressed an electric motor starts from standstill with the connected load and accelerates until it reaches full speed. What is happening in the motor is very stressful because the inrush current can be 5 to 10 times the operating current during the acceleration time. This causes tremendous heat in the rotor and stator. This heat translates to thermal expansion and movement. This movement over time will lead to failure. If a motor is not allowed to cool between starts it will subject the stator winding and rotor bars and rings to high thermal conditions and will greatly shorten the life of a motor. Playing with Electricity! Thermal damage Grounded winding Winding overload showing overall heat damage and a ground failure Rotors account for up to 10% of failures Cracked Bar Cracked shorting ring Examples of excessive starting/stopping and the resultant rotor damage Bar to Ring crack Bar lifting out of rotor slot Don’t Overload a motor like this! Contamination Internal External Contamination internal and external both causing over heated windings A motor that hasn’t been maintained… When replacing or installing motors these are the important parameters to focus on: • • • • • • • • • The original motor nameplate: The nameplate holds a lot of valuable information often over looked. Performance information (Including the Speed vs. Torque curve and the maximum inertia the motor was designed for). The original load “Speed vs. Torque” curve and inertia (WK² in units of LB-FT²) The actual system starting voltage (Or voltage drop during start). The inrush current capability of the control starting system. (I.e. Breaker or contactor or other) You must match the KVA code or be aware of the differences between the original and new/used motor replacement.. The service factor needs to be understood… The motor temperature rise needs to be understood…. The motor enclosure…the motor frame dimensions and details FAILURE INVESTIGATION PROVIDING SOLUTIONS • THE GOAL IS TO PROVIDE SOLUTIONS TO YOUR MOTOR/SYSTEM PROBLEMS. • FOCUSING ON THE DETAILS HELPS TO SUPPORT A BETTER UNDERSTANDING OF WHAT IS ACTUALLY WRONG WITH YOUR SYSTEM AND/OR MOTOR. • IT BEGINS WITH OBTAINING SPECIFIC INFORMATION ABOUT THE MOTOR BEING REMOVED FROM SERVICE. BACKGROUND INFORMATION • • • • • • • What is the Application? How long has motor been in service? What is the environment surrounding the motor? What are the starting conditions for the motor? What is the Reason for removing the motor? What predictive measures and trends support removing the motor? The past repair history and trends? DETAILED INSPECTIONS • • After obtaining the specific background information for your motor we then begin the process of a detailed inspection. For each motor being repaired, HECO has developed unique “Repair Packets” that provide a step by step approach to the inspection for each specific motor type. Example: AC Sleeve Bearing Motor Repair Packet A.C. SLEEVE BEARING MOTOR REPAIR PACKET REVISION SUMMARY Page No. Description Prepared By: Date: Approved By: Date: Revision # 16 REPLACED THE CAUSE OF FAILURE WITH MOTOR OBSERVATIONS/FINDINGS DMN 1/21/14 TAH 1/21/14 12114 17 ADDED A PLACE TO RECORD HECO/CUSTOMER ASSET # AND TO CONFIRM LEADS IN TERMINAL BLOCKS DO NOT HAVE METAL TAGS. DMN 1/21/14 TAH 1/21/14 12114 18, 19, 20 REMOVED THE CALIBRATED INSTRUMENT LOG AND THE PARTS CLEANING REVIEW PAGE. THESE WERE REPLACED WITH COMBINED DEPARTMENTAL FORMS FOR BOTH, CALIBRATION AND FINAL Q.A. DMN 1/21/14 TAH 21/21/14 12114 3 ADDED A PLACE FOR KLIXONS AND RATING. DMN 4/21/14 AJ 4/21/14 42114 5 ADDED A PLACE TO DOCUMENT MEGS BEFORE PREHEAT AND THE PART TEMPERATURE BEFORE D/B DMN 4/21/14 AJ 4/21/14 42114 ACSLMRP REV 42114 OBSERVATIONS AND FINDINGS With every inspection, HECO will document the Observations and Findings for that particular motor. This information focuses on what we found during the inspection process and how this information relates to your reason for motor removal. We then categorize our findings into 4 areas: • • • • Electrical Mechanical Contamination Preventative Maintenance MOTOR OBSERVATIONS / FINDINGS JOB: _________ CUSTOMER: ____________________ DATE: _______________ EMPL# ___________ APPLICATION: _____________________________________________ TYPE OF STARTING: ___________________________________________ TIME IN SERVICE: _______________ REASON FOR REMOVAL OF UNIT: ________________________________________ SUMMARIZE ACTUAL FINDINGS: RELATIVE PICTURE #’ S RECOMMENDATIONS / COMMENTS: COMMENTS OR ADDITIONAL INFORMATION REQUIRED: CHECK THE PRIMARY CATEGORY TO FINDINGS, THEN IN NUMERICAL ORDER, NUMBER OTHER FINDINGS AS A RESULT OF PRIMARY ELECTRICAL MECHANICAL CONTAMINATION TURN TO TURN PHASE TO PHASE GROUNDED BEARING LUBRICATION SHAFT WATER CHEMICALS OIL SINGLE PHASED VIBRATION DIRT LEADS BLOWN SHAFT CURRENTS CARBON PARTIAL DISCHARGE SHAFT MAGNETISM PLUGGED FILTERS OVER HEATING SEALS PLUGGED VENTS SURGE / SPIKE SIZE / TOLERANCE ISSUE CONTAMINATION INSULATION DEGRADATION OTHER: OTHER: PM STANDARD P.M. OTHER: INFORMATION REVIEWED BY: ____________________________ DATE: _________________ 2/20/14 MIF v2 MOTOR OBSERVATIONS / FINDINGS JOB: _9636__ CUSTOMER: _DETROIT EDISON__ DATE: _12/20/14_ APPLICATION: _COAL MILL MOTOR___ TYPE OF STARTING: ____ EMPL# __422___ ACROSS LINE____ TAG# MMO00091 TIME IN SERVICE: _N/A_ REASON FOR REMOVAL OF UNIT: _TRIPPING BREAKER ON START-UP__ SUMMARIZE ACTUAL FINDINGS: MOTOR WAS SENT IN DUE TO TRIPPING BREAKER. FOUND SLEEVE BEARING WIPED WHICH CAUSED ROTOR TO DRAG STATOR WHICH GROUNDED WINDING. RELATIVE PICTURE #’ S TD: 22, 23, 36, 37, 38, 39, 40, 44, 60, 67, 68, 78, 96, 100, 101, 104 RECOMMENDATIONS / COMMENTS: RECOMMEND CUSTOMER MONITOR BEARING TEMPERATURES TO ALLOW FOR A SHUTDOWN BEFORE CATASTROPHIC FAILURE. COMMENTS OR ADDITIONAL INFORMATION REQUIRED: THIS IS A REPETATIVE DESIGN CHANGE ON THE ROTOR. HECO IS INSTALLING A HECO ROTOR DESIGN, ADDITIONAL TO ALL OTHER REPAIRS. CHECK THE PRIMARY CATEGORY TO FINDINGS, THEN IN NUMERICAL ORDER, NUMBER OTHER FINDINGS AS A RESULT OF PRIMARY X MECHANICAL ELECTRICAL TURN TO TURN 3 2 CONTAMINATION BEARING WATER PHASE TO PHASE LUBRICATION CHEMICALS GROUNDED SHAFT OIL SINGLE PHASED VIBRATION DIRT LEADS BLOWN SHAFT CURRENTS CARBON PARTIAL DISCHARGE SHAFT MAGNETISM PLUGGED FILTERS OVER HEATING SEALS PLUGGED VENTS SURGE / SPIKE SIZE / TOLERANCE ISSUE CONTAMINATION INSULATION DEGRADATION ROTOR RUBBED STATOR I.D. OTHER: OVERLOADED OTHER: 1 OTHER: ROTOR RUBBED STATOR IRON INFORMATION REVIEWED BY: __AL JESKE______ DATE: __12/20/14____ PM STANDARD P.M. MOTOR OBSERVATIONS / FINDINGS JOB: _7236_ CUSTOMER: _LTV____ DATE: __12/2/13_ APPLICATION: _PICKLE PLANT__ TYPE OF STARTING: TIME IN SERVICE: _6 MONTHS EMPL# _506__ ___SOFT__________ REASON FOR REMOVAL OF UNIT: _BEARING NOISE___ SUMMARIZE ACTUAL FINDINGS: DURING INCOMING TEST RUN, MOTOR HAD A NOISY BEARING. UPON DISMANTLE, FOUND WATER IN THE D.E. HOUSING. THE D.E. BEARING FAILURE WAS DUE TO MOISTURE ENTERING THE HOUSING, CONTAMINATING THE GREASE. THE HOUSING WAS OVERSIZE. RELATIVE PICTURE #’ S 7, 8, 9, 13, 15, 16, 22 RECOMMENDATIONS / COMMENTS: Add an impro seal to the drive end to help prevent water entering. COMMENTS OR ADDITIONAL INFORMATION REQUIRED : CHECK THE PRIMARY CATEGORY TO FINDINGS, THEN IN NUMERICAL ORDER, NUMBER OTHER FINDINGS AS A RESULT OF PRIMARY ELECTRICAL TURN TO TURN X CONTAMINATION MECHANICAL 2 BEARING 1 WATER PHASE TO PHASE LUBRICATION CHEMICALS GROUNDED SHAFT OIL SINGLE PHASED VIBRATION DIRT LEADS BLOWN SHAFT CURRENTS CARBON PARTIAL DISCHARGE SHAFT MAGNETISM PLUGGED FILTERS OVER HEATING SEALS PLUGGED VENTS SIZE / TOLERANCE ISSUE CONTAMINATION INSULATION DEGRADATION ROTOR RUBBED STATOR I.D. OTHER: OVERLOADED OTHER: SURGE / SPIKE 3 PM STANDARD P.M. OTHER: INFORMATION REVIEWED BY: __AL JESKE______ DATE: __2/11/14___ 2/20/14 MIF v2 TRENDING OF INFORMATION • We gather this information over time on a spreadsheet and begin to develop valuable data about the categories and areas that your motor problems fall into. This information is eventually provided back to you to help you in your preventative maintenance and to support your decisions for deciding what motors should be removed and what areas you may need additional support & training. DETROIT EDISON PRIMARY #1 MECHANICAL BEARING PM - OUTAGE PM SIZE/TOLERANCE U2 W. COOL WATER MOTOR PM - OUTAGE PM NORTH MAIN VACUUM PUMP PM - OUTAGE PM FRAME MODEL S/N APPLICATION 3030S6 129 1-5116-11444-2-3 UNIT 2 #7 COAL MILL TRIPPED BREAKER 365TZ TDFC 7008 MTG TURNING GEAR 326TS 5KS326STE115 S85098343 364TS SD2P75TS61Y U3980906280 7295-9 N/A 280277411 P.A. FAN MOTOR 326TS DVH326TSTF56536FVL 7109905-07/20-02 "A" TRAIN ANION PUMP REASON SENT IN ???? SATURATED WITH OIL / INSTALLING SPARE PM #2 #3 ROTOR RUBBED STATOR IRON GROUNDED LUBRICATION BEARING SIZE/TOLERANCE WATER BEARING SIZE/TOLERANCE MECHANICAL SEALS OIL DIRT ELECTRICAL INSULATION GROUNDED LUBRICATION Finding the Root Cause & Providing Repair Solutions HECO is well known for solving problems with Electric Motors. As we partner with our customers, we begin to understand where repetitive problems are occurring & through this process of asking better questions and understanding the customer, we can provide improved motor designs to support the elimination of repetitive failures. Engineering Design Evaluations & Assessments In our evolution of identifying motor problems and providing a solution, we will often go another step and provide our customers with a Detailed Engineering Assessment. The beginning of this process is gathering more information specific to your application. In all cases we will ask the customer for original design information about the load (such as “Speed vs. Torque” Curve and Inertia Wk² of the load and original motor performance information) DESIGN CHANGE INFORMATION SHEET DATE REQUEST TAKEN:_________________ HECO JOB #:___________________ CUSTOMER NAME:_______________________________ CUSTOMER CONTACT:__________________________ PHONE # OR EMAIL:__________________________________ HECO SALESMAN:__________________________ ORIGINAL DESIGN DATA EQUIPMENT TYPE: INDUCTION MOTOR ____ TRANSFORMER ____ MFG: ________________ HP / KW: ____________ RPM: ____________ TYPE: ____________ FRAME: ______________ SYNCHRONOUS ____ WOUND ROTOR ____ OTHER:__________________________ VOLTAGE (AC OR DC): _____________ AMPS (AC OR DC):____________ DESIGN: ______________________ STYLE: ____________ DC ____ S.F.:_______________ CODE: ____________ MODEL: _______________________ SERIAL: ________________________ (FLD. DATA) VOLTS DC: ____________ RESISTENCE: _____________ TEMP.:________________ TEMP. RISE:_________________ AMBIENT REQUESTED REDESIGN CHANGE TO ______________ HP / KW _________________ VOLTAGE _____________RPM __________________OTHER ___________________________________________________________________________________MECHANICAL NOTES: _______________________________________________________________________________________ ______________________________________________________________________________________________ QUESTIONS TO ASK CUSTOMER 1. 2. 3. 4. 5. 6. 7. 8. 9. PURPOSE OF DESIGN CHANGE? _______________________________________________________________ APPLICATION (ie. LOAD) ? ______________________________________________________________________ LOAD SPEED V/S TORQUE CURVES (NEED THIS FOR COMPLETE DESIGN CHANGES, ATTACH TO FORM) TYPE OF STARTER (IE. ACROSS THE LINE, ETC.) ? ________________________________________________________ DOES UNIT START UNDER LOAD: ____ OR UNLOADED ____ INERTIA OF LOAD; WK² = _______ HOW LONG HAS THE UNIT LASTED OR BEEN IN THE ORIGINAL DESIGN? ___________________ # OF STARTS PER HOUR OR DAY? _____________ DUTY CYCLE:________ HRS./WEEK ACTUAL MEASURED VOLTAGE: ________________ CURRENT: _______________ SPEED: _______________ (HECO CAN MEASURE IF NEEDED) SKIN TEMPERATURE: ______________________ APPROVED REDESIGN CHANGE ________________HP / KW _______________VOLTAGE _______________RPM _____________ AMPS _______________ OTHER _____________________________________________________________MECHANICAL S.F.: ___________ INSULATION CLASS: _______________ NOTES:_______________________________________ ______________________________________________________________________________________________ APPROVED BY: ________________ DATE:____________ CUSTOMER APPROVAL: __________________ DATE:_____________ DCIS Rev.2014 Real example for a Utility The following is an example of what we have talked about in this presentation. Back in 2006 HECO was offered the opportunity to review motor failures common to a Utility Company Coal Mill Motors. (I.e. Siemens Allis, 800HP, 890 RPM, 4000 Volt, 112 Amp, horizontal, sleeve bearing motors). At that time the customer provided back ground information to HECO and expressed the need for a solution that would be long lasting and truly solve the repetitive motor problems they were experiencing. There were a total of 32 Coal mill motors (30 in service with 2 spares). Issues found with these motors These motors are a special design which has a double rotor bar cage assembly. This is needed due to the hard conditions of a coal mill application and required torques needed. Double cage rotor design After dismantling these motors the problems centered around the rotor design. The original problem was cracking of the inner cage shorting rings. Additional problems Porosity & Cracks In the outer shorting ring fan assembly More problems Application information was obtained from the Utility on the existing motors. Note: In every Engineering Design Assessment the following information is important to obtain, to successfully identify/compare and perform a complete design verification review. Obtaining the original performance and load information is vital in providing alternative solutions to your problems. • • • • It provides details about the original motor design. It provides load information needed for engineering calculations and torque requirements. It allows a cross check of the new design to the original and how they compare. It confirms whether a design will work or not. Samples of the bar/shorting ring materials were sent to a laboratory for identification. The analysis came back as follows: BARS The upper bar (Outer cage) was .500” diameter and had a conductivity of 23.6% (Copper alloy). This was identified as C464 Naval Brass. The lower bar (inner cage) was .375” wide x 1.00” tall and had a conductivity of 98.6%.This was identified as 99.9865% copper, C11000 (Pure copper). SHORTING RINGS The upper shorting ring (outer cage) was a phosphorous copper alloy with a conductivity of 63.5%. This copper alloy was not directly identified with today’s alloys but its closest match was C21000. This shorting ring also had the cooling fan “casted” as part of the shorting ring. This causes the shorting ring configuration to be special thus adding cost and longer material deliveries. (In other words, this design isn’t practical for repairing in the future, because the shorting rings would have to have a special copper alloy casting to match the original configuration. This causes the repairs to take longer and is more costly.) The lower shorting (inner cage) was a phosphorous copper alloy with a conductivity of 60.1%. This copper alloy was also not directly identified with today’s alloys but being closest to C21000. This ring was slotted as shown below. NOTE: This shorting ring design is mechanically weaker due to the machined slots in the ring. Due to the original design configuration of both inner and outer shorting rings, HECO is offering an alternative to both ring designs. The inner ring has inherent weakness due to the slotted design. HECO has designed an alternative ring that is mechanically stronger and 1/8” thicker (Original ring 3/8” thick and new trough style ring ½” thick). This ring design is called a “Trough” ring where the bars are inserted into a machined trough in the face of the ring. This trough is silver soldered to short & connect all the bars electrically and mechanically. (An example of a similar design is shown below. This design is larger but the concept is the same). Machining the “Trough” of a larger ring. The photos above show the vertical set up and (15% Silver Brazing) welding of the bars in the trough design. When complete the bars/shorting ring joint is mechanically much stronger. The ring is then machined to a final size and the rotor is cleaned of all flux etc. The outer shorting ring would be a shorting ring as original, except without the fan blades as part of the ring. We would offer a fabricated steel fan (Same shape/blade area and number of blades) that would either mount to the shaft or the shaft spider assembly. This design would provide cooling fans that are removable and allow for better inspection of the shorting rings and an improved design for future repairs (a more practical approach for future repairing and rotor bar/shorting ring replacement. After performing an engineering design analysis, we have identified that the original ring material (60% conductivity) is not necessary for the performance or motor torque requirements. This same performance can be achieved by replacing with a 100% copper shorting rings (100% conductivity). This provides a more readily available shorting ring material option for this repair and future repairs (The current material is a material that is more costly and is not readily available (approximately 6 – 8 weeks). As with most induction rotors of this speed (# of poles) the shorting rings play a very small role in the production of torque. The resistivity (or conductivity) of the bars are the most important component for production of torque and performance. HECO’s concept for the new design would follow the sketch below: . Note: The “Trough” style inner ring at ½” thick (original 3/8” thick). Both rings would be made from 100% copper (100% conductivity). This design will allow for an improved mechanical design (Inner ring) and a more practical material selection (for shorting rings). This will allow future rotor repairs to be simplified and not dependent on a material that is not available or a long lead time. Motor torque is effected by the bar resistance (which consists of: bar length, bar area, # of bars and the bar conductivity) and ring resistance (which consists of: ring thickness, mean diameter, ring area, # of (poles)², and ring conductivity). The change in ring resistance is minimal and the bar resistance is still the dominant factor producing the majority of motor torque. What does this mean in terms of performance? Following is a chart that compares the performance difference of the original rings (60% conductivity) to the new copper rings (100% conductivity). Original LRT 224 % BDT 275 % LRA 728 Stall Time 3.2 Acc. Time 3.0 Rotor Bar (°C) 111 Rotor Ring (°C) 6 New 222 % 272 % 726 3.1 3.0 110 5 As you can see, the effect of changing the rings to copper is very small in relation to performance. New Rotor details and pictures Storage Maintenance Storing for Reliability A motor in storage on-site is there for one primary purpose: It needs to be available for quick installation when an operating production motor goes down. Maintenance of electric motors in storage is a critical, but often over-looked function. Performing a few, relatively simple maintenance items during storage will help ensure a motor is ready to be installed and operates reliably. Storage Problems Problems that may occur during extended motor storage basically fall into two categories • Coil insulation deterioration Condensation collects on the stator coils, eventually lowering insulation resistance to ground • Bearing damage Condensation contaminates bearing grease Grease hardens and loses it’s ability to lubricate Stationary brinelling of the bearing race Storage Recommendations • • If at all possible, electric motors should be stored in a clean, dry, low humidity environment. • This will help prevent condensation buildup on windings and bearings If motors are equipped with space heaters, they should be energized. Storage Recommendations Machines with oil lubricated bearings require being filled with oil when motor enters storage (Motors ship dry from the factory) Rotate the motor shafts quarterly. • Distributes lubricant to machined surfaces • Prevents false brinelling damage Grease motor bearings require re-lubrication during extended storage. • Every 6 months to a year during extended storage Storage Recommendations continued • During extended storage, all motors should have their insulation resistance checked and recorded at periodic intervals. • • A 50% drop in the resistance-to-ground requires corrective action Correct insulation resistance to ground (Megger) for temperature changes following IEEE 43-2000 and trend. The Motor System “Systems” Approach • • • • Utilizing A foundation based on experience, we suggest a systems approach to motors and equipment reliability. This foundation is built on solving electric motor problems and providing long term solutions. In addition we direct our focus from only the motor, to include the reliability of the complete system. Many of the problems & solutions are found to be in other parts of the system, I.e. foundation, alignment, driven equipment, etc. Asking detailed questions, beyond the motor; including the application, supports creating a better understanding of the whole system which provides for long term solutions. 12 Step HECO MAPPS (Motor And Powertrain Performance System) HECO MAPPS HECO MAPPS is designed to optimize the performance of your electric motor-driven powertrains. MAPPS will lead you to reducing downtime costs, keeping problems from recurring and keeping your operation running. Step 1: Equipment Survey & Identification • Survey all assigned equipment • Record all nameplate data & other critical data • Tag each asset individually with unique ID number • Identify asset plant location and application information • Categorize assets and applications • Enter survey data into reliable database (Such as HECO’s TracRat database system) Survey Sheet Example (Motor Only) Step 2: Review Practices & Implement Specifications • • • • Identify existing repair and new purchase specification practices for each asset type Review existing practices and makes recommendations to improve quality and consistency Creation of corporate specifications with specific exception reports per plant area and application Implement specifications by asset types and sizes Step 3: Review Procurement Processes • Assess existing new & repair procurement process • Establish new v/s repair determination levels • Review and implement authorization process • Implement procurement process that is based around reliability and established specifications Step 4: Perform Partner Assessment • Survey all partners across all asset types/sizes • Tour all partners across all asset types/sizes • Establish partner certification process • Select partners based on assessment results • Create partner volume discounts Step 5: Spare Asset Management • Centralized v/s Decentralized storage • Identify “current” storage practices & locations • Including preventative maintenance practices • Identify “proper” storage practices and locations • Identify min and max levels • Identify “cross-over” assets • Reaction time of storage centers HECO’s 170,000ft2 warehouse in Hammond, IN Step 6: Asset Repair Management • Establish pricing format for high volume assets • Develop approval process for repairs • Establish cause of failure evaluation process • With a focus on root cause analysis • Audit & continually improve partners • Track all repair history in one common location Step 7: Predictive and Preventative Maintenance • Assess current practices • Establish practices, as needed • • • • • • Vibration practices Thermography practices Electrical Evaluation practices Lubrication practices Alignment practices Oil Particle Analysis Step 8: Dedicated Technical Specialists • On-Site validation of all critical assets • Oversee removal and installations • Assist partners with root cause failure analysis • Make recommendations on proper operation • Work with all maintenance groups • Monitoring of all critical asset application conditions • Continuous documentation & record keeping Step 9: Engineering and Applications • • • • Identify proper repair methods with an engineering and reliability focus Take a “systems” approach to failures Use historical data to your advantage to put the proper piece of equipment in the proper application Focus on system improvements Step 10: Training • Assessment of current knowledge levels • Establish training programs based on current skill levels • Establish and implement training around the needs identified by the assessment reports Step 11: Software Database • Central communication database (Like HECO’ s TracRat) for all repairable assets • Never loose historical information – it’s like a “medical record” for your repairable assets • • • • Track all repair history and new purchases in one location across all asset types Warranty tracking Repair statuses Cause of failure reporting • • • • By location, asset type, manufacturer, failure types, etc. Mean Time Between Service (MTBS) reporting Ease of access to information through internet and web browser Adaptable to track additional information Step 12: Establish KPI’s • • • • • MTBS (Meantime Between Service) Down time dollars by asset type Asset Repair Cycle Report Savings report Inventory reports • • • • • (Key Performance Indicators) Min/Max Levels In-Service to Spare analysis Inventory amount reports On-Time delivery reporting Dollar spend v/s budget by repairable asset type Communication • • • • • Single control point – Between customer and partner Focus on long term reliability and cost savings/avoidances Create reliability team focus on each asset type Schedule regular improvement meetings with each asset reliability team Create an aligned focus on corporate goals NIPSCO 20 YEAR CASE STUDY NIPSCO Early years • Didn’t know how many motors they had in-service or as spares • Didn’t have any detailed specifications that they followed • Repair specifications was generic • No specific Capital or replacement spec • RFQ process was driven by low prices not by a apple to apple comparison • Many vendors no Partners • Pour communications • No database system for tracking • No consistency with budgeting • Firefighting not having time to get to the root of the failures • Repeating Failures no accountability • No detailed history on failures and past repairs • Not looking at things as a complete powertrain system NIPSCO 20 YEAR CASE STUDY NIPSCO after a HECO MAPPS (Motor And Powertrain Performance System) • • • • • • • • • • • • • • Surveyed over 12,000 motors Detailed Specifications One focused Partner On Site Technical Specialist Fixed Pricing Failure assessment and correction Trust in a Reliable systems Better Budgeting and Planning Lower cost of doing business Clear communication TracRat web based database Training Focused Team from HECO and Customer Millions in documented savings Thank you Questions?