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.

1. Eco-Mode: Benefits and Risks of
Energy Saving Modes of UPS
Operation
Schneider Electric Data Center
Science Center White Paper #157

2. Introduction
This paper shows that eco-mode
typically provides a
reduction of about 2% in data
center energy consumption
and explains the various
limitations and concerns that
arise from eco-mode use.
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 2

3. 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

4. Simple diagram of power flow of a double-conversion,
online UPS……
Bypass Path
STATIC BYPASS
SWITCH
Online Path
AC
DC
DC
AC
RECTIFIER INVERTER
BATTERY
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 4

5. Online and Eco-Mode Operation
Online mode Eco-mode Comment
Normal
Eco-mode
exposes operation Rectifier/Inverter Bypass the
load to raw
mains
O li d
During a power
disturbance Inverter Inverter
Online mode
requires no
path change
during power
disturbances
During a fault Bypass Bypass Extremely rare
condition event
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 5

6. Output waveforms of 275 kVA UPS in eco-mode
responding to a power failure……
Upper waveform is output voltage, lower is output current
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 6

7. 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
supply 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

8. 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

9. Additional advantage of advanced eco-mode…
●Improved filtering function
●Reduces harmonic injection back into
Utility mains or standby generators
●In principle, filtering function works at
nearly the same level and quality as a
double 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

10. Advantages come with a tradeoff…
●Overall efficiency of the UPS is less
●It’s a small difference, however…
●0.5% - 1.0% range
●Efficiency 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

11. Efficiency Improvements: PUE of Typical
Data Centers
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 11

12. Efficiency Improvements: PUE
Improvement
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 12

13. Efficiency Improvements: Eco-mode
Eco-mode corresponds to a savings of 3.3% of total energy use and US
$20 000 year
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

14. Efficiency Improvements: Eco-mode (1/2)
Considerations of eco-mode
include:
•Loss of electrical protection
Energy saved depends on:
•Specific equipment
•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

15. 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
operating range.
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 15

16. Lost of Protection: Response to Power
Problems
1 • Power problem is detected p
• UPS determines how to 2 respond
3 • UPS inverter is energized*
4 • Transfer switch is actuated
*NOTE: in advanced eco-mode, inverter is already energized
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 16

17. Loss of Protection: Power Problem
Situations
Power problems:
● Transformers may trip breakers
● Loss of power leads to overloads
and dropped loads
● Protective devices on pumps and
fans may operate
● 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

18. 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

19. Reliability Impacts: Thermal Shock and
Cycling
Eco-mode:
•Primary cause of failure of electronic
power systems
•Applied when UPS is needed the most
Normal UPS operation:
•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

20. Reliability Impacts: Battery Life
Battery Operating
Temperature
•Battery Wear
•Eco-mode requires
transfer more Strongly affected by UPS
design
•May operate at higher
t t i d
often
•Wear depends on
implementation of eco- temperatures in eco-mode
mode
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 20

21. Reliability Impact: Fault Clearing
When 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

22. Effect on Operations: Consequences
Testing for Adjusting
capability
sensitivities
or delays
Establishing Utilizing
procedures
power
p forensics
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 22

23. Conclusion
As data center designs become more
standardized, IT equipment
continues to improve, and real world
experience using eco-mode
accumulates, predictability and
confidence in eco-mode will improve
and 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

24. Resources List
The Different types of UPS Systems
APC White Paper 1
Making Large UPS Systems More Efficient
APC White Paper 108
An Improved Architecture for High-
Efficiency, High-Density Data Centers
APC White Paper 126
Browse all APC white papers
http://whitepapers.apc.com
Browse all APC TradeOff Tools™
htt //http://t l
tools.apc.com
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 24

25. Thank You
Questions?
© 2014 Schneider Electric All Rights Reserved – Eco-mode: Benefits and Risks of Energy Saving Modes of UPS Operation – June 2014 25