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Many newer UPS systems have an energy-saving operating mode known as "eco-mode" or by some other descriptor. Nevertheless, surveys show that virtually no data centers actually use this mode, because of the known or anticipated side-effects. Unfortunately, the marketing materials for these operating modes do not adequately explain the cost / benefit tradeoffs. This presentation shows that eco-mode provides a reduction of approximately 2% in data center energy consumption and explains the various limitations and concerns that arise from eco-mode use. Situations where these operating modes are recommended and contra-indicated are also described.
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Eco-Mode: Benefits and Risks of E S i M d f UPSEnergy Saving Modes of UPS Operationp
Schneider Electric Data Center Science Center White Paper #157
Introduction
This paper shows that eco-mode typically provides a reduction of about 2% in datareduction of about 2% in data center energy consumption and explains the various limitations and concerns that
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 2
arise from eco-mode use.
Eco-mode Introduction
•Overall system architecture•Right-sized system design•Individual devices•Operational decisions
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 3
Simple diagram of power flow of a double-conversion, online UPS…online UPS…
STATIC BYPASS
Bypass Path
SWITCH
Online Path
DCAC
DCAC
RECTIFIER INVERTER
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 4
BATTERY
Online and Eco-Mode Operationp
Online mode Eco-mode Comment
NormalEco-mode exposes theNormal
operation Rectifier/Inverter Bypass exposes the load to raw mainsO li d
During a power disturbance Inverter Inverter
Online mode requires no path change during powerduring power disturbances
During a fault Bypass Bypass Extremely rare
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 5
condition Bypass Bypass event
Output waveforms of 275 kVA UPS in eco-mode responding to a power failure…responding to a power failure…
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 6
Upper waveform is output voltage, lower is output current
Advanced eco-mode
●Result of recent advances in firmware control schemes and electrical design
●Primary power path during normal operation is the same as standard or “classical” eco-mode: through the bypass path
●But, the inverter remains “ON”, operating in parallel with the input w/o actually handling the load current
●Since the inverter is already “ON”, it can more seamlessly take over the y , ysupply to the output when there is a mains failure
Schneider Electric Galaxy VM UPS with ECOnversionTM
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 7
Standard vs. advanced eco-mode
UPS operating in standard eco-mode
UPS operating in advanced eco-mode
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 8
Additional advantage of advanced eco-modemode…
I d filt i f ti●Improved filtering function ●Reduces harmonic injection back into Utility mains or standby generators●In principle filtering function works at●In principle, filtering function works at nearly the same level and quality as a double conversion UPS not operating indouble conversion UPS not operating in eco-mode
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 9
Advantages come with a tradeoff…
Overall efficiency of the UPS is less●Overall efficiency of the UPS is less●It’s a small difference, however…●0.5% - 1.0% range●Efficiency less than standard, but better thanEfficiency less than standard, but better than traditional online mode
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 10
Efficiency Improvements: PUE of Typical Data CentersData Centers
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 11
Efficiency Improvements: PUE ImprovementImprovement
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 12
Efficiency Improvements: Eco-mode
Eco-mode corresponds to a savings of 3.3% of total energy use and US $20 000 per year
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 13
$20,000 per year.
Efficiency Improvements: Eco-mode (1/2)
Considerations of eco-mode include:•Loss of electrical protection
Energy saved depends on:•Specific equipment•Loading of data center p
•Reliability impacts•Operations issues
Loading of data center•Cost of electricity
These factors often cause operators to decide against eco-mode.
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 14
Loss of Protection: UPS Systems
Virtually all equipment sold today is immune to mains frequency variations and designed to accommodate any variations of mains voltage within a specified
ioperating range.
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 15
Lost of Protection: Response to Power ProblemsProblems
1 • Power problem is detected1 p
• UPS determines how to respond2 • UPS determines how to respond
3 • UPS inverter is energized*
4 • Transfer switch is actuated
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 16
*NOTE: in advanced eco-mode, inverter is already energized
Loss of Protection: Power Problem SituationsSituations
Power problems:Power problems:● Transformers may trip breakers● Loss of power leads to overloads
and dropped loadsand dropped loads●Protective devices on pumps and
fans may operate●Non-server IT devices are not●Non server IT devices are not
robust in handling dips and sags●Static switches cannot protect
loads from overvoltage
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 17
Harmonics & eco-mode…
Harmonic issues will not be a factor in most data centers, but the use of eco-mode may require that
they be studied or mitigated.
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 18
Reliability Impacts: Thermal Shock and CyclingCycling
Eco-mode:•Primary cause of failure of electronic power systemspower systems•Applied when UPS is needed the most
Normal UPS operation:p•No shock when power fails•UPS will go into bypass
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 19
Reliability Impacts: Battery Life
Battery Operating Temperature•Strongly affected by UPS
Battery Wear•Eco-mode requires transfer more often Strongly affected by UPS
design
•May operate at higher t t i d
transfer more often
•Wear depends on implementation of eco temperatures in eco-modeimplementation of eco-mode
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 20
Reliability Impact: Fault Clearing
When the UPS is in eco mode it can beWhen the UPS is in eco-mode, it can be very difficult to distinguish an output fault from a loss of input power: an additional factor that should be considered.
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 21
Effect on Operations: Consequences
AdjustingTesting for capability
Adjusting sensitivities or delaysor delays
UtilizingEstablishing procedures
Utilizing power
forensicsp forensics
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 22
Conclusion
As data center designs become more standardized, IT equipment continues to improve and real worldcontinues to improve, and real world experience using eco-mode accumulates, predictability and confidence in eco-mode will improve
d it li ti b i tand its application may begin to expand, especially in data centers with lower availability requirements.
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 23
Resources ListThe Different types of UPS SystemsAPC White Paper 1
Making Large UPS Systems More EfficientAPC White Paper 108
An Improved Architecture for High-Efficiency, High-Density Data CentersAPC White Paper 126
Browse all APC white papers http://whitepapers apc comhttp://whitepapers.apc.com
Browse all APC TradeOff Tools™htt //t l
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 24
http://tools.apc.com
Thank You
Questions?Questions?
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 25
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