Energy Saving in Electric Motor Systems

Electric Motors … Electric Motor Systems

The Electric Motor System E= E e * E m

Why Motors Are Important Electric motors consume more than 50% of all electricity consumed in the United States (38.5% in IRAN)

Industrial electricity Use

Industrial Motor Energy Use by Application

كل انرژي الكتريكي در شاخه ‌ هاي مختلف مصرف، مطابق آمار وزارت نيرو

Motor Content in IRAN :

مصرف انرژی موتورهاي الكتريكي در شاخه ‌ هاي مختلف مصرف

بزرگترين مصرف كنندگان ( برحسب درصد ):

Electricity Consumption Comparison US : 2001 IRAN : 1379

Why Energy Saving !

In the US: –motors use 23% of all electricity consumed –motors use 69% of all industrial electricity consumed Other countries, developed and developing, have similar or even more pronounced motor consumption patterns. For example: In China: –motors use 54% of all electricity consumed Why Care About Electric Motors?

A small increase in efficiency can realize large savings

Why Energy Saving in Motors Considerable Potential Opportunities for Energy Saving in Electric Motors A small increase in efficiency can realize large savings Some opportunities are inexpensive to implement

A Motor Can Consume Its Capital Cost in Just 40 Days Continuous Operation Days of Operation Motor Capital Cost / Energy Cost (%)

For a 100 hp motor operating for 15 years at $0.05/kWh Purchase Cost = $5,000 Energy Costs = $525,000

Saved Energy Is Pure Profit…..

Potential Motor System Savings in US

Potential Motor System Savings Based on the US DOE study, implementing viable motor systems savings projects can reduce motor system energy consumption in manufacturing by about 15%.

Potential Savings in Pump Systems

Potential Savings in Fan Systems

Potential Savings in Compressor Systems

Potential Motor System Savings Total Electricity Consumption : Motors Electricity Consumption : Potential Electricity Saving : IRAN 28 e9 18 e9 3 e9 US 1085 e9 kWh 680 e9 kWh 85 e9 kWh

چند پروژه انجام شده در صنايع آمريکا

End User Case Studies 3M Company

كارخانه صنعتي 3M اين كارخانه بزرگ كه در ايالت مينه سوتا واقع است و محصولات مختلف صنعتي و تجاري توليد مي ‌ كند، از ژانويه سال 1994 كار بهينه ‌ سازي مصرف انرژي توسط موتورهاي الكتريكي خود را آغاز نمود. اين كارخانه موفق گرديد با سرمايه ‌ گذاري به ميزان $1,600,000 به صرفه ‌ جويي معادل $ 823,000 در سال دست يابد كه زمان بازگشت سرمايه ‌ آن معادل 1.94 سال است.

كارخانه فولاد Bethlehem اينديانا اين كارخانه براي ماندن در صحنه رقابت، به دنبال كاهش هزينه ‌ هاي مصرف انرژي بوده و در پروژه بهينه ‌ سازي خود موفق شد مصرف انرژي خود را به ميزان 15,500 MWh معادل 50 % كاهش دهد. سرمايه گذاري اوليه اين شركت معادل $ 1,125,000 بوده كه صرفه ‌ جويي به ميزان بيش از $ 620,000 در سال با زمان بازگشت سرمايه كمتر از 2 سال را باعث گرديده است.

كارخانه General Motors Pontiac ميشيگان اين شركت به منظور بهينه ‌ سازي مصرف انرژي الكتريكي مورد نياز سيستم آب شرب مصرفي كارخانه برنامه مديريت مصرف انرژي در موتورهاي الكتريكي را پياده نموده است. سرمايه ‌ گذاري اوليه اين پروژه به ميزان $ 44,900 بود كه منجر به صرفه ‌ جويي معادل $11,200 در سال گرديد.

كارخانه توليدي Johnson & Johnson اين كارخانه در پي بهينه ‌ سازي مصرف انرژي سيستم Dust Collector كه شامل واحدهاي متشكل از موتورهاي الكتريكي 50hp, 25hp و واحد 20 hp مي ‌ باشد موفق گرديده با سرمايه ‌ گذاري اوليه ‌ اي به ميزان $50,000 به صرفه ‌ جويي سالانه ‌ اي معادل $ 35,000 دست يابد.

كارخانه توليد لاستيك Greenville آركانزاس اين كارخانه موفق گرديد با سرمايه ‌ گذاري در پروژه ‌ اي، در يكي از خطوط توليد خود با استفاده از روشهاي مديريت مصرف انرژي در موتورهاي الكتريكي به صرفه ‌ جويي معادل 148,847 kWh دست يابد. سرمايه ‌ گذاري اوليه اين شركت $ 37,190 بوده و صرفه ‌ جويي اقتصادي سالانه آن $ 77,266 با زمان بازگشت سرمايه ‌ اي كمتر از 6 ماه بوده است.

Motor efficiency = Motor output / Motor input = 13.8kW (estimated) / 14.9 kW = 0.93, or 93% Pumping Systems: Motor Only The Electric Motor System

Pumping Systems: Motor + Pump P suction = 28 psig P discharge = 80 psig Combined pump + motor efficiency = Pump output / Motor input = 10.2 / 14.9 = 0.69, or 69% The Electric Motor System

Pumping Systems: Motor + Pump + Valve More than 40 psi drop across the throttle valve Package efficiency = Hydraulic output / Motor input = 2.7 / 14.9 = 0.18, or 18% The Electric Motor System

Energy Consumption in Electric Motor Systems E : ميزان انرژي الکتريکي مصرفي، (kWh) P : توان بار مورد نظر، (kW) t : زمان مصرف انرژي الکتريکي، (h) η : بازده انرژي سيستم موتور الکتريکي c : هزينه واحد انرژي الکتريکي مصرفي، (Rls/kWh) C : ميزان هزينه انرژي الکتريکي مصرفي، (Rls)

براي بهينه سازي مصرف انرژي در سيستمهاي موتور الكتريكي بايد : توان بار کاهش يابد. زمان مصرف انرژي الکتريکي کاهش يابد. بازده انرژي سيستم موتور الکتريکي افزايش يابد. هزينه واحد انرژي الکتريکي مصرفي کاهش يابد.

روش بهينه سازي مصرف انرژي موثر روي 1 بهبود كيفيت توان تغذيه موتور η 2 مديريت زمان کارکرد موتور t, c 3 انتخاب درست موتور براساس بار η 4 استفاده از ادوات انتقال نيروي مکانيکي با بازده بالاتر η 5 استفاده از موتورهاي با طراحي بهتر η 6 کنترل سرعت موتورهاي الکتريکي P 7 استفاده از دستگاه هاي کنترل عملکرد η 8 نگهداري و تعمير مناسب ( برنامه نت ) P,η روشهاي بهينه سازي مصرف انرژي در موتورهاي الكتريكي

Power Quality

موتورهاي الكتريكي و به خصوص موتورهاي القايي براساس كار با ولتاژ متعادل سه فاز كاملاً سينوسي با ولتاژ نامي و فركانس نامي طراحي مي ‌ شوند. هرگونه انحراف از اين شرايط، بازده موتور را كاهش خواهد داد.

مواردي كه جهت حصول توان با كيفيت، بايستي مدنظر قرار گيرند عبارتند از : تامين ولتاژ نامي تامين فركانس نامي نامتعادلي ولتاژ در محدوده مجاز ( 1%) نبود محتوي هارمونيکي حصول ضريب توان بالا

اثر تغييرات ولتاژ بر عملكرد موتور

Voltage Unbalance

رابطه derate شدن ( کاهش توان نامي ) موتور با نامتعادلي ولتاژ تغذيه

رابطه derate شدن ( کاهش توان نامي ) موتور با ولتاژ تغذيه هارمونيکي ضريب ولتاژ هارمونيکي (HVF) Vn : اندازه هارمونيک ولتاژ مرتبه n n : مرتبه هارمونيک

Running Time Management

اقدامات عمده خاموش كردن موتور در هنگامي كه مورد نياز نباشد توقف موتور در هر ساعت براي مدتي تنظيم شده ‌ جابه جايي زمان کار موتور از دوره اوج بار به دوه کم بار و عادي

کنترل On/Off پمپ ها و كمپرسورها كه هنگام بسته بودن شيرها كار مي ‌ كنند. موتور ماشينهايي كه در حال توليد و يا عليرغم حل مشكلات ماشين باز هم روشن و در حال كار باقي مي ‌ مانند. ماشين ‌ افزاري كه در مدت استراحت براي صرف غذا و يا بين عمليات مختلف برشكاري روشن باقي مي ‌ ماند.

Energy Saving … Motor & Load Matching

Electric Motors … A/C Induction Motors

Induction motors The most common type of electric motors about 90%.

 Low Cost  Robust and Reliable  Low Maintenance  Simple to Install  Easy Availability Why Do We Use Them? A/C Induction Motors

Induction Motor Rating as per IEC

مشخصه گشتاور - سرعت يك موتور القايي نمونه به همراه مشخصه بار

Motor Partial Load Factor Efficiency and power factor are a function of motor load Motor Load Efficiency or Power Factor Efficiency Power Factor

Motor Partial Load Factor

Motor Partial Load Efficiency

Reasons for Over Sizing: Extract form DETR Best Practice Guide 1998

Motor Part Loads in the US Office of Energy Efficiency & Renewable Energy US Dept. of Energy

Energy Saving … Determining Motor Part Load

Determining Part Load … Input Power Measurement

Determining Part Load … Line Current Measurement

Determining Part Load … The Slip method

Determining Efficiency … On site efficiency

Energy Saving … More Efficient Transmissions

- تجهيزات انتقال نيرو شامل محورها، تسمه ها، زنجيرها و چرخ ‌ دنده ها بايستي به ‌ درستي انتخاب و نصب شوند. - استفاده از تسمه هاي سنكرون و يا زنجير به جاي تسمه هاي V شكل

Energy Saving … Energy Efficient Motors

Efficiency

Motor Efficiency & Losses

Iron loss in core - Low loss steel - Thinner laminations Bearing friction & windage loss = 23% - Smaller cooling fan Rotor loss Copper loss = 20% - Optimum slot fill - Larger conductors Stray loss = 7% - Improved slot geometry 50% Breakdown of Loss Components

Motor Load (%) Loss (% FL) Iron LossF & W LossStator Cu LossRotor Al LossStray Loss

Induction Motor Losses

A/C Induction Motors Energy Losses Within a Motor Stator Copper Loss Rotor Conductor Loss Iron Loss Friction & Windage Loss Stray Load Loss

Loss Calculations P Fe and P fr,w : from no-load test P stator and P rotor : from R, s and P in P additional : can not be measured directly JEC 37: assumes P additional = 0 IEC : P additional = 0.5%. P in IEC : P additional by measurement or fixed amount depending on motor rating

A/C Induction Motors Single-phase Equivalent Circuit Stator Current Rotor Current Load No Load Current Stator Supply Voltage

Stray Load Loss Best method of determining P additional : calculate P additional for various load levels as Linearise and correct for measurement errors in function of torque squared as

Determining SLL

Measurement set-up

Efficiency of motors should meet Standards

Efficiency standards Europe: IEC , and the new IEC US: IEEE Method B Japan: JEC 37 Difference in efficiency value: up to 3% Why such a difference?

in U.S. IEEE

Standard Induction Motor Efficiency

Energy Efficient Motor Efficiency

in EU IEC

مقايسه بازده موتورهاي الكتريكي بيش بازده، پربازده و استاندارد در اروپا

Efficiency Against Load 25% 96 Load Efficiency % %75%Full Load Energy Efficient Standard 6.5% 3%

Characteristics of Energy Efficient Motors Typical Data for 7.5kW, 4 Pole Motor Load Power Factor Standard Energy Efficient

Calculation of Energy Saving for EEMotors

Calculation of Simple Payback for EEMotors

Upgrading one, 1 Horse power motor to a Premium Efficient motor.... Every year will eliminate: 1 Drum of Oil from being burned 520 lbs. of coal from being burned Up to 1,400 lbs. of carbon emissions from being released into the atmosphere That is just one year Motors can last up to 15+ years and.... or....

Energy Saving … Replacement vs. Repair

Economics of Replacement vs. Repair Depends on many factors... Running hours Load Cost of electricity Cost of new motor Cost of motor repair

The Real Cost of Rewinding a Motor It is generally considered that repairing a motor is the low cost option, but even a good rewind will reduce motor efficiency by up to 0.5% Example: 15kW motor with an Efficiency of 90.0% Annual running cost = £ Motor rewound with an Efficiency of 89.5% Annual running cost = £5,028

Efficiency of Repaired Motors Few empirical studies done -- mostly motors 50 hp and under 77 motors studied, reported efficiency decreased between 0 to 2.5% after repair Average is.5 to 1% efficiency loss Efficiency degradation lower for large hp motors Efficiency loss can be minimized with quality repair

Replacement vs. Rewinding Size (kW) Annual Running Hours Repair Replace

Energy Saving … Adjustable Speed Drive

Energy saving … Adjustable Speed Drives ASD’s give significant savings in energy !!!

Adjustable speed drive

Why Variable Speed? Motor power is a function of shaft load Load is a function of flow and pressure Reducing flow can reduce power significantly Affinity Laws Flow -- speed Pressure -- speed 2 Power -- speed 3

Experimental results - Drive Variable speed drive, using induction motor and frequency converter Energy saving potential up to 50% in –pump drives –ventilator drives –compressor drives –… when compared with fixed speed on/off, throttle or bypass system What with efficiency between drives?

ç Motor Torque vs. Load Torque Escalators Motor Torque Loading Weekly Duty Cycle 100% Average Load SundayMondayTuesdayWednesdayThursdayFridaySaturday A Variable Load

Adjustable speed drive

Adjustable Speed Drives

New York State Variable Speed Drive Farm Program kWh in millions Before VSD Saved After kWh in Millions

Energy Saving … Performance Controller (Soft start)

ç Direct On Line ç Star Delta ç Auto Transformer ç VSD / Inverter Drive  Soft Start Current Popular Options Starting of Motors

Current Torque Motor Current Speed In 6-10 x In 100% N X Nominal Motor Torque Speed 100% N Excess Starting Torque Excess Starting Current Direct On Line Starting of Motors

ç Initially Relatively Low Cost. ç Simple Advantages: Starting … DOL

ç No Torque Control. ç High In-Rush Current. ç Damage To Plant Control Gear. ç Control Gear Maintenance Cost. Disadvantages: Starting … DOL

çTorqueçCurrent Transition Peak up to 20 x In Excess Starting Current Motor Current Speed 100% N 6-10 x In In X Nominal Motor Torque Speed 100% N Delta Torque Star Torque Load Torque Excess Acceleration Torque 0.66 Starting of Motors Star Delta

ç Initially Relatively Low Cost. ç Simple ç Reliable In Theory - However In Practice Causes Many Other Problems. Advantages: Starting … Star Delta

ç Fixed Torque Reduction. ç Transition Peak. ç Damage To Plant Control Gear. ç Control Gear Maintenance Cost. Disadvantages: Starting … Star Delta

çTorque çCurrent Motor Current Speed 100% N 6-10 x In X Nominal Motor Torque Speed 100% N Motor Torque Load Torque Stepped Acceleration In Starting of Motors Auto Transformer

ç More control than a Star Delta. ç Proven Technology. ç Reliable In Theory - However In Practice Causes Many Other Problems. Advantages: Starting … Auto Trans

ç Difficult To Design - Often One off. ç Expensive & Timely To Replace. ç Large Size. ç Control Gear Maintenance Cost. Disadvantages: Starting … Auto Trans

çCurrent çTorque Motor Current Speed 100% N 6-10 x In Direct on Line Current Current Limit Start Current Ramp Start X Nominal Motor Torque Speed 100% N Motor Torque Load Torque Powerboss Torque Acceleration Torque 1 1 Unused Starting Current Unused Starting Torque Starting of Motors Soft Start

ç Low Capital Outlay. ç Complete Control - little on going maintenance. ç Proven Technology. ç When a motor cannot be slowed down, a Soft Start is the most effective way to start and stop it. Advantages: Starting … Soft Start

ç Adjustable Pedestal Voltage. ç Adjustable Ramp Time. ç Adjustable Current Limit. ç Solid State Electronics - Little Maintenance. Disadvantages: Starting … Soft Start

ç Stator & Rotor Ohmic Loss & Stray Load Loss vary with Load ç Iron Loss & Mechanical Loss (Friction & Windage) nearly are constant to Load. ç Iron Loss about 20% of total Loss. ç Energy optimizer by decreasing voltage decrease Iron Loss & therefore increase efficiency. Motor Losses Starting …Optimizer

ç in Loads near Full-Load decreasing voltage may cause increasing current & increasing Ohmic Losses! & then increasin total Loss ---> Decreasing Efficiency ç Just for Loads near no-load “Energy Optimizer” may decrease total losses by decreasing Iron Loss. ç Any reputable optimizing soft starter will achieve between 40-50% saving of iron loss. Motor Losses Starting …Optimizer

ç Soft Start / Soft Stop. ç Match Motor and Load Torque. ç Accurate Control Of Motor Current - Intelligent Reactive Energy Optimisation. ç Reduction Heat / Noise / Vibration. çNo adjustment required once fitted - marries with motor. Advantages: Starting …Optimizer

Energy Saving … Preventive Maintenance

عدم نگهداري مناسب منجر به … - افزايش تلفات - افزايش دما - كاهش بازده مي گردد.

اثر درجه حرارت سيم پيچ بر عمر عايقي موتورهاي الكتريكي

برنامه تعمير و نگهداري مناسب شامل … - انجام بازديدهاي دوره ‌ اي - كنترل دما - روغن ‌ كاري منظم -...

Energy Saving … Lesson Learned

Emphasize systems approach Develop portfolio of system-based products and tools Recognize end users and suppliers who are leaders Need for showcases to use as examples that can be duplicated Look for groups (suppliers, utilities, consultants) to promote program

A Motor Management Policy Energy Saving...