1. Increasing the Efficiency of UPS Systems – And Proving It!
Richard L. Sawyer
Director, Critical Facilities Assurance
EYP Mission Critical Facilities

2. The Problem 60% of US Energy bill is in buildings.
Energy consumed by data centers more than doubled between 2000 and 2005 – J. Koomey, Stanford University.
U.S. Data center electrical bills totaled $2.7 Billion in 2005.
A single, moderate size server in a data center has the same carbon foot print as a SUV that gets 15 MPG (R.Muirhead, Data Center Journal).
A single rack with 6 Blade Server units consumes as much power as 3 kitchen electric ranges (24-30Kw)!

3. Relative Power Densities

4. 21st Century Computing – Blade Servers
Power = Up to 6 kW per Blade chassis or 30 kW per rack

5. Where does the power go? UPS = 18%
Actual IT Load is 30% of Power Consumed
APC-MGE: Neil Rasmussen

6. UPS OUTPUT POWER INPUT POWER FROM UTILITY/GENERATOR
DISTORTION
SPIKE
SWELL
SAG
OUTAGE
Lightning Strikes
Faulty Switchgear
Storms
High Winds
Falling Trees
Traffic Accidents
Heavy Loads
Poor Distribution
Switching Operations
Poor Filters
Faulty Load Eq.
Static Electricity
RF Interference
Harmonics/
Electronic Loads
FREQUENCY
Major Utility
Problems
Faulty
Generator
INPUT POWER
FROM
UTILITY/GENERATOR
UPS
OUTPUT POWER
PURPOSES OF UNINTERRUPTIBLE POWER SUPPLY
1.Maintain clean, uninterrupted power during utility events
2.Power Conditioning
3.Isolation from other electrical loads
4.Separately Derived Source of Power

7. Strategy to Improve UPS Efficiency
IBM Blue Gene 1.2 Megawatt
Technology: Make the units more efficient.
Selection: Size the units more closely to the load.
Application: Use redundancy only where it is needed.

8. Understanding UPS Inefficiency Factors
No-Load Losses
Proportional Losses
Square-Law Losses
Paying the price to process power!

9. EPRI Efficiency Curves for UPS Products

10. Typical UPS efficiency curve
Below 30% load efficiency drops rapidly
Nominal 92% efficiency only applies when UPS load is over 70%
100%
90%
80%
70%
60%
UPS Efficiency
50%
40%
30%
20%
10% 0% 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
UPS Load % of full power rating

11. 13.5 KV
13.5 KV
2(N+1) System
480
480
Each side must have capacity to support both critical loads but maintain redundancy.
Total load cannot exceed capacity of 2 UPS Modules.
EFFECTIVE DESIGN LOAD = 33% of total capacity, maximum.
Primary Bus A
Primary Bus B
UPS
UPS
UPS
UPS
UPS
UPS
Bypass A
Bypass B
Load Bank
Load Bank
UPS Output 2A
UPS Output 2B
Subsystem Bus A
Subsystem Bus B
Critical Load Bus A
Critical Load Bus B
Static
Switch
Static
Switch
PDU
PDU
Critical Load

12. Aggregate UPS Power Losses
No-load portion of loss stays constant from full load all the way down to zero load { }
No-load loss is present even at no load
Many data centers
operate in this range
UPS load
% of full power rating
100%
90%
80%
70%
60%
50%
40%
30%
20%
10% 0%
Power delivered to load
UPS internal power consumption (loss)
93.4%
93.3%
93.1%
92.8%
92.4%
91.8%
90.7%
88.9%
85.5%
76.4%
EFFICIENCY
Proportional and square losses

13. No Load Losses
Definition: The power consumed by the UPS at 0% load just to keep the UPS operating.
Sources – Transformers, capacitors, logic systems, fans, communications cards.
Sometimes referred to as “tare”, “constant”, “fixed”, “shunt” and “parallel” losses.
Most significant inefficiency: Accounts for up to 40% of UPS losses.

14. Proportional Losses
Definition: The power needed to process more power through the UPS.
Sources – Switching losses, capacitor and inductor impedance, internal resistance
Proportional losses increase as the output load the UPS support increases.
Proportional losses are directly related to the topology (internal design) of the UPS.

15. Square - Law Losses
Definition: Losses related to the amount of current flowing through the UPS.
Power is the result of voltage times the current.
Current does the work, and power is lost as the amount of current flowing increases, by a square factor, hence “square – law losses”.
Power loss is in the form of heat.
Square-Law losses are 1% to 4% at higher load levels.

16. Power Loss Component Graph
No Load
Electrical Loss in kW
(Waste due to inefficiency)
Equipment Loading
Full Load
50%
10%
30%
90%
70%
NO-LOAD loss
PROPORTIONAL loss
SQUARE-LAW loss
TOTAL LOSS

17. (Waste due to inefficiency)
Two devices with same nameplate efficiency can have significantly different losses in actual operating range, due to the particular characteristics of their PROPORTIONAL and NO-LOAD losses
Example: Two different 100kW UPSs with 92% nameplate (full-load) efficiency
Same nameplate efficiency (full-load loss)
10kW
Loading where most data centers operate
Electrical Loss
(Waste due to inefficiency)
UPS A TOTAL LOSS
UPS B has higher proportional loss (steeper line) but lower no-load loss
UPS B TOTAL LOSS
UPS A No-load loss
UPS B No-load loss
But different performance at actual operating load
0kW
No Load
10%
30%
50%
70%
90%
Full Load
Equipment Loading

18. 10kW 0kW Electrical Loss Equipment Loading
One device can even have WORSE nameplate efficiency than another, yet have lower loss in actual operating range, if it has a low NO-LOAD loss
Example: Two 100kW UPSs with same 92% nameplate (full-load) efficiency
UPS A has better nameplate efficiency (lower full-load loss)
10kW
Loading where most data centers operate B A
Electrical Loss
(Waste due to inefficiency)
UPS A TOTAL LOSS
UPS B has higher proportional loss (steeper line) but lower no-load loss
UPS B TOTAL LOSS
UPS A No-load loss
UPS B No-load loss
But UPS B performs better at actual operating load
0kW
No Load
10%
30%
50%
70%
90%
Full Load
Equipment Loading

19. Technology Selection Application
Improving Efficiency
Technology
Selection
Application

20. Improving Efficiency – Fixing No-Load Loss
Effect of lowering NO-LOAD LOSS
Example: 100kW UPS with 92% full-load efficiency
10kW
Nameplate efficiency goes from 92% to 94.5%
Same improvement in nameplate efficiency
Loading where most data centers operate
Total loss before improvement
Electrical Loss
(Waste due to inefficiency)
Total loss after improvement
Electric bill savings
Original No-load loss
But waste is roughly cut in half in actual operating range
Lowered No-load loss
0kW
No Load
10%
30%
50%
70%
90%
Full Load
Equipment Loading

21. Improving Efficiency – Fixing Proportional Loss
Effect of lowering PROPORTIONAL LOSS
Example: 100kW UPS with 92% full-load efficiency
10kW
Nameplate efficiency goes from 92% to 94.5%
Loading where most data centers operate
Total loss before improvement
Electrical Loss
(Waste due to inefficiency)
Total loss after improvement
Electric bill savings
(Unchanged No-load loss)
Waste is reduced by 10-20% in actual operating range
0kW
No Load
10%
30%
50%
70%
90%
Full Load
Equipment Loading

22. Application Efficiency – Zoned RedundancyM
CRAC
pdu
UPS
Cold
Aisle
Hot F I R E S C U
HEAT
REJECT
EPO
SYSTEM
MONITOR
WEBLINK
Site Availability – %
$2,000+ per square foot
Battery
Central UPS for one “N” side, scalable, modular system
Rack Based UPS Systems as needed for 2N redundancy

23. Commissioning UPS Systems
Availability
The Cost of Downtime
The Value of Commssioning

24. Data Center Tier Ratings
* The Uptime Institute

25. Maximizing Availability
Total Time - Downtime
Availability =
Total Time
The only variable is Downtime
Downtime sources: Equipment Failures, Human Error, External Causes, Maintenance
Cost of Downtime drives the Value of CFA!

26. What does Downtime Cost?

27. Infant Mortality Period High Probability of Downtime
The Reliability Curve for equipment (IEEE)
Infant Mortality Period
End-of- Life Period
High Probability of Downtime
Failure Rate
Time (Data Center Life Span)
“The Bathtub Curve”

28. Infant Mortality Period
The Value of Commissioning
Infant Mortality Period
End-of- Life Period
Minimize
Failures
Time

29. Commissioning UPS Systems
Verify the full load performance of each module using load banks – typical burn in is 4 hours at rated KW load (hint: infrared inspections of all connections).
Measure and verify the efficiency in the full operating range at 5%, 10%, 15%, 20%, 25%
Verify system redundancy under design load levels.
Verify failure modes (under-voltage transfers, bypass transfers, over load shutdown).
Verify isolation modes for concurrent maintenance.
Assuring you get the reliability and efficiency you pay for!

30. Richard L. Sawyer 518-337-2049 rsawyer@eypmcf.com
Questions?
Richard L. Sawyer