Avoiding Mis-Information when Assessing the Energy Saving Potential of Motor-Driven Applications in Buildings
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The document presents insights from the emex 2017 conference on energy efficiency and the importance of accurate assessment in industrial energy consumption, particularly with electric motors. It highlights the significance of considering system efficiencies rather than just product efficiencies to avoid misleading conclusions and optimize energy savings. The analysis also warns against oversizing and emphasizes the impact of technology and proper equipment selection on achieving energy efficiency.
Avoiding Mis-Information when Assessing the Energy Saving Potential of Motor-Driven Applications in Buildings
- 1. 22ND 23RD NOVEMBER 2017 EMEX 2017 Energy Efficiency Surveys – Avoiding the Pitfalls John Guthrie; UK Energy Efficiency Manager – ABB Drives
- 2. • Calculatingenergy consumption &interpretingthe Cube Law • Product & System efficiencies – avoiding the Catalogue Trap! November 28, 2017 Slide 2 Agenda
- 3. RisingDemand Energy – Is it Still an Issue? November 28, 2017 Slide 3
- 4. EuropeanPower Plant Development:2005 - 2030 Energy – Is it Still an Issue? November 28, 2017 Slide 4
- 5. RisingCost Energy – Is it Still an Issue? November 28, 2017 Slide 5 0 20 40 60 80 100 120 140 160 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Index2010=100 Industrial Fuel Price Indices in Current Terms 1994 - 2016 Coal Heavy Gas Electricity Total Source: DECC Quarterly Energy Prices; Sep 17
- 6. Fast and cheap: technology isalready available Energy – Is it Still an Issue? November 28, 2017 Slide 6 “Improvingenergy efficiency worldwide isthe fastest, the most sustainable and the cheapest way to reducegreenhousegas emissionsand enhance energy security.” (Final statement of G-8 summit, Germany, June 2007) “On average,an additional dollar investedin moreefficientelectrical equipment,appliancesand buildingsavoidsmorethan two dollarsin investmentin electricity supply.” (International Energy Agency's World Energy Outlook)
- 7. Why the focus on electric motors? November 28, 2017 Slide 7 65% industrial electricity consumed by electric motors 95% of motors are oversized
- 8. Design oversizing November 28, 2017 Slide 8
- 9. In this situation, what do you do? November 28, 2017 Slide 9 70 A: Take your foot off the gas B: Or keep it on and use your brakes to slow you down
- 10. Balloon machine demo November 28, 2017 Slide 10
- 11. — Assessing the potential Avoidingmiss-information when assessingthe Energy usage & savings potential
- 12. Variable Torque Load November 28, 2017 Slide 12 0 10 20 30 40 50 60 70 80 90 100 100 80 60 40 20 0 Motor Nameplate Fixed Speed with Damper Cube Lawcurve VSD Centrifugal Load CurvesPower% Speed %
- 13. Variable Torque Load November 28, 2017 Slide 13 0 10 20 30 40 50 60 70 80 90 100 100 80 60 40 20 0 Motor Nameplate Fixed Speed with Damper Cube Lawcurve VSD Centrifugal Load CurvesPower% Speed %
- 14. — Assessing the potential Consideringsystem efficiencies
- 15. Product vs System Efficiency November 28, 2017 Slide 15 Where are we at today?
- 16. Product vs System Efficiency November 28, 2017 Slide 16 What new standards are comingin future? Variable Speed Systems EN50598-1 and EN50598-2 Individual Product efficiency is normally givenat a fixed operating point The nature of Variable Speed Systems is that the systemis variable – the clue is in the name! Easy comparison of catalogue values givenat nominal power does not present the full picture & can lead to inaccurate results EN 50598-2 allows some flexibility with regard to how figures are calculated / measured and therefore are not always like for like
- 17. Energy Efficiency Interactions of Products in Systems November 28, 2017 Slide 17 Hardware components used (or not used) in the VSD – Choke / Line Filter (presence /% Value) Software / configurationof the VSD parameters – Motor magnetisationoptimisation(Energy / Flux Optimiser) (Software feature) and flux pattern(quadratic vs linear) – Switching Frequency (software feature) Harmonics (Supply Side) – K-rating (k-factor) Harmonics (Motor Side) Many factors influence system efficiency
- 18. Theoretical (usingCataloguedata at nominal load) November 28, 2017 System Efficiency = 0.98*0.98*0.94 = 90.3%Slide 18 Interaction of Products – Simplified Model 98% 98% 94% Electrical Energy Input Mechanical Energy Output 6 Pulse Drive 4 kHz Switching Frequency
- 19. In reality - DOL at nominal duty & typical harmonic background November 28, 2017 System Efficiency = 0.98*0.925 = 90.6%Slide 19 Interaction of Products – Simplified Model 98% 92.5% (Due to harmonic content on supply Network) Electrical Energy Input Mechanical Energy Output
- 20. In reality……….. at nominal load November 28, 2017 System Efficiency = 0.97*0.98*0.92 = 87.5%Slide 20 Interaction of Products – Simplified Model 97% Due to harmonics 98% 92% Due to VSD waveform Electrical Energy Input Mechanical Energy Output 6 Pulse Drive 4 kHz Switching Frequency
- 21. Change of SwitchingFrequency from4 to 2 kHz November 28, 2017 System Efficiency = 0.97*0.985*0.91 = 86.9%Slide 21 Interaction of Products – Simplified Model 97% 98.5% Lower Switching Frequency = Lower VSD losses 91% Lower Switching Frequency = Higher motor losses Electrical Energy Input Mechanical Energy Output 6 Pulse Drive 2 kHz Switching Frequency
- 22. Change of SwitchingFrequency from4 to 8 kHz November 28, 2017 System Efficiency = 0.97*0.965*0.93 = 87%Slide 22 Interaction of Products – Simplified Model 97% 96.5% Higher witching frequency = higher VSD losses 93% Higher switching frequency = lower motor losses Electrical Energy Input Mechanical Energy Output 6 Pulse Drive 8 kHz Switching Frequency
- 23. Harmonic Filter + 6-Pulse Drive November 28, 2017 System Efficiency = 0.98*0.98*0.92 +PQF Filter loss = 87.2%Slide 23 Interaction of Products – Simplified Model 98% 98% 92% Electrical Energy Input Mechanical Energy Output 6 Pulse Drive 4 kHz Switching Frequency PQF Filter Additional Loss
- 24. ‘Normal’Duty – 30% speed reduction November 28, 2017 System Efficiency = 0.965*0.9675*0.91 = 85% (of 35% of the nominal power)Slide 24 Interaction of Products – Simplified Model 96.5% Lower Efficiency due to Lower Load 96.75% Reduced efficiency due to Lower Load 91% Reduced efficiency due to Lower Load Electrical Energy Input Mechanical Energy Output 6-Pulse Drive 4 kHz Switching Frequency Efficiency appears Low Energy Saving from Speed Control >60%
- 25. Energy Efficiency - Conclusions VSD control of centrifugal loads - context November 28, 2017 Slide 25 – 2Hz reductionin fan / pump speed = 10 -12% reductionin energy – Simply using the motor nameplate data & cube law will overestimate the savings – The Catalogue Trap is easy to fall into – Different designs & configurations produce wildly different results on paper – Correct selectionof equipment & carful setup & commissioning will provide best results. Overallsystemefficiency & actuallosses are what is important. Efficiency Figures in Context 0 20 40 60 80 100 120 0 20 40 60 80 100 Power Flow (%) Power to pump to produce useful flow Power to throttle controlled pump Power input to VSD controlled pump Power consumed by throttled DOL pump Power actually needed to produce required flow Power consumed by VSD to achieve required flow
- 26. Energy & Productivity Appraisal Team November 28, 2017 Slide 26
- 27. Questions… November 28, 2017 Slide 27