Motor Efficiency and Legislation Electric Motor Applications

Transcription

1 Motor Efficiency and Legislation Electric Motor Applications Presented by Shermco Industries 1

2 Topics Introduction NEMA Motor Efficiency Legislation Quality of Power Maintenance Repair, Recondition, Rewinding Summary Presented by Shermco Industries 2

3 Introduction 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 Presented by Shermco Industries 3

4 Introduction This presentation will cover different areas of concern as it pertains to motor efficiency and recent legislation that affects new motors (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 Presented by Shermco Industries 4

5 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 Presented by Shermco Industries 5

6 NEMA 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. Presented by Shermco Industries 6

7 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. Presented by Shermco Industries 7

8 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 Presented by Shermco Industries 8

9 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. Presented by Shermco Industries 9

10 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. Presented by Shermco Industries 10

11 Motor Efficiency 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 Presented by Shermco Industries 11

12 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. Presented by Shermco Industries 12

13 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% Presented by Shermco Industries 13

14 Legislation 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 110 th Congress and signed it into law on December 19, 2007 by President George W. Bush. The Law becomes effective on December 19, 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 Presented by Shermco Industries 14

15 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 Presented by Shermco Industries 15

16 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) Presented by Shermco Industries 16

17 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 Presented by Shermco Industries 17

18 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 Power Quality 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. Presented by Shermco Industries 18

19 Power 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 Presented by Shermco Industries 19

20 Power Quality 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. Presented by Shermco Industries 20

21 Power Quality 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 Presented by Shermco Industries 21

22 Power Quality 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. Presented by Shermco Industries 22

23 Power Quality 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. Presented by Shermco Industries 23

24 Power Quality Online Testing Power and current signature online motor testing programs allow for the evaluation of motor circuit performance during operation and detect problems before they occur. Online is divided into Current Analysis and Voltage Analysis Current Analysis looks at the rotating components Loose or broken rotor bars cracked end rings rotor eccentricity misalignment and coupling/belt problems Voltage Analysis looks at Power quality issues like harmful harmonics voltage imbalances under/over-voltages Presented by Shermco Industries 24

25 Power Quality 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. Presented by Shermco Industries 25

26 Power Quality Faults that Off Line and On Line tests will Identify 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) Presented by Shermco Industries 26

27 Power Quality 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 Presented by Shermco Industries 27

28 Power Quality 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. Presented by Shermco Industries 28

29 Power Quality 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 Presented by Shermco Industries 29

30 Maintenance 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 Presented by Shermco Industries 30

31 Maintenance 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 Presented by Shermco Industries

32 Maintenance Laser Alignment Maintenance Aligns motor mechanically to increase efficiency and bearing wear Presented by Shermco Industries 32

33 Maintenance 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 Presented by Shermco Industries 33

34 Maintenance 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 Presented by Shermco Industries 34

35 Maintenance 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 Presented by Shermco Industries 35

36 Vibration Analysis Maintenance 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. Presented by Shermco Industries 36

37 Maintenance 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. Presented by Shermco Industries 37

38 Maintenance 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. Presented by Shermco Industries 38

39 Maintenance 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? Presented by Shermco Industries 39

40 Amplitude Maintenance Spectrum Analysis Techniques (cont.) 1x 2x 3x 4x Frequency 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. Presented by Shermco Industries 40

41 Amplitude Spectral Pattern Recognition Maintenance < 1X low frequency rotational events and harmonics high frequency events (i.e. imbalance, misalignment, looseness, etc.) (i.e. bearing or gearmesh) 1x 10x 2x 3x 4x Frequency Over time, the successful analyst recognizes spectral patterns as representing specific machinery problems. Presented by Shermco Industries 41

42 Maintenance 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 Presented by Shermco Industries 42

43 Repair, Recondition, Rewinds 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. Presented by Shermco Industries 43

44 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 Repair, Recondition, Rewinds Demonstrate and maintain a certified quality assurance program based on EASA-Q or ISO-9000 The following photos show what maintenance can find: Presented by Shermco Industries 44

45 Repair, Recondition, Rewinds Cleaning? Presented by Shermco Industries 45

46 Repair, Recondition, Rewinds Prevented? Presented by Shermco Industries 46

47 Repair, Recondition, Rewinds Insulation Failure? Presented by Shermco Industries 47

48 Repair, Recondition, Rewinds Catastrophic Failure? Lamination Damage? Presented by Shermco Industries 48

49 Repair, Recondition, Rewinds 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. Presented by Shermco Industries 49

50 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. Repair, Recondition, Rewinds Presented by Shermco Industries 50

51 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. Repair, Recondition, Rewinds Presented by Shermco Industries 51

52 Repair, Recondition, Rewinds 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. Presented by Shermco Industries 52

53 Laminations Repair, Recondition, Rewinds 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 deburred laminations that have the same material composition, dimensions, and inter laminar insulation characteristics as the original lamination assembly is permitted. Presented by Shermco Industries 53

54 Repair, Recondition, Rewinds Thermal image of core test showing hot spot near core end Presented by Shermco Industries 54

55 Repair, Recondition, Rewinds Coating may be damaged during improperly performed rewind Increased iron losses Lower efficiency Hotter operation Presented by Shermco Industries 55

56 Repair, Recondition, Rewinds 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 Presented by Shermco Industries 56

57 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 Presented by Shermco Industries 57

58 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. Presented by Shermco Industries 58

59 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 Presented by Shermco Industries 59

60 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 Presented by Shermco Industries 60

61 Organizations National Electrical Manufacturers Association - Institute of Electrical and Electronics Engineers EASA - Electrical Apparatus Service Association Baker Test Equipment Baldor and WEG Motors Presented by Shermco Industries 61

62 Notes on NEMA NEMA defines, in NEMA MG 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 ( % 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 ( % of full load), low breakdown torque ( % 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. Presented by Shermco Industries 62