The document compares costs and reliability of different emergency power system topologies for data centers. It finds that systems using integrated paralleling are more reliable at lower cost. While medium voltage increases price, it does not significantly improve reliability. Scalability allows modular reliability improvements. Case studies of four data centers show successful implementations of redundant bus and distributed redundant topologies. In conclusions, standardization, modularity and scalability are driving factors in new emergency power system designs.

1. EMERGENCY POWER
TOPOLOGIES AND EVOLUTION
7X24 Fall Phoenix
Curt Gibson PE ATD
Power Solutions Manager
Generac Industrial Power
(209) 483-3910
Curt.Gibson@Generac.com

2. Introduction
 Curt Gibson
 Data Center Specialist for Generac
 2 – 3 data centers per week
 Accredited Tier Designer
 Registered Professional Engineer
 20 years in engineering of Emergency
Power Systems for ASCO and Generac
2

3. Goals Today
 Compare costs and reliability of different topologies
 Reliability
 Cost
 Scalability
 Four case studies
 University of Utah
 Venyu Data Center
 C7 Data Centers
 Green House Data
 Question and Answer
3

4. Typical Data Center Concerns
 Energy efficiency
 True reliability and availability
 Cost efficiency
 Return on investment
 Scalability
4

5. Recent Trends
 Shorter lead times, just in time
 Cost competition
 Less custom
 Modularity
 Standard products, off the shelf
 Widely available support
5

6. Modular Era
 Cost competitive
 Future proof
 Higher efficiencies
 Scalable
 Repetitive designs
 Economies of scale
 Lower cost of ownership
6

7. Paralleling Benefits
 Paralleling is easier now
 Improves reliability
 Lowers cost
 Makes systems more scalable
 Offers more availability
7

8. Traditional Approaches
 Custom controls
 Specialty schemes
 Larger generators
8

9. Paralleling Controls are Evolving
 Smaller digital controllers
 Every major manufacturer
 (Cat, Cummins, MTU, Kohler, Generac)
 Costs are decreasing
 Standardization provides reliability and modularity
9

10. Comparison of Concepts
 N = 5MW
 N+1 during all three construction phases
 Co-location data center
 Outdoor installation
 24 hour tanks
 80dB enclosures
 Four load buses
 480V loads
10

11. Economical Design Guidelines
 Transformer size (<4MVA)
 Generator size (<2500kW)
 Interrupt ratings (<100kAIC)
 Bus capacity (<6000A)
 Transfer Switch (<4000A)
 Breaker Size (<5000A)
 Distance ($200/ft/MW)
11

12. Uptime Institute Tier Requirements
TIER REQUIREMENTS Tier I Tier II Tier III Tier IV
Number of Delivery Paths 1 1
1Active
1Passive
2Active
Redundancy N N+1 N+1
N after any
failure
Compartmentalization No No No Yes
Concurrent Maintainability No No Yes Yes
Fault Tolerance No No No Yes
12
 Often confused with
“Common Attributes”
 Tier IV does not require
2N capacity
 Compartmentalization
includes dead lugs
when servicing
 Automatic fault
response is typical in
Tier III

13. Reliability Calculations
13
 Not “Availability”
 Simple equations
 Only to the UPS
 Probability the load is
fed
 Assumed 98% for
generators
 Assumed 99.9% for
buses
 Stattrek.com calculator
 IEEE 3006.7

14. Cost vs Reliability
14

15. Medium Voltage 2N, T4, PR
$2250 $750 $750 $3750 99.994%
Phase 1 Phase 2 Phase 3 Total
Reliability15
 2N systems
 Tier 4 Compliant
 Parallel Redundant
 Main-Tie-Main
 MV Paralleling
Switchgear
 Unit Substations
 Utility on the bus
 Breaker pair transfer
 Reliability
 (N4, n2, P0.98) = 0.99996
 1- ((1-0.999) X 1-(0.999)) = 0.99999
 N4, n2, P0.999 = 0.99999
 (0.99996)(0.99999)(0.99999)= 0.99994
A

16. Medium Voltage, N+1, T2, DR
$2000 $650 $650 $3300 99.645%16
Phase 1 Phase 2 Phase 3 Total
Reliability
 N+1 systems
 Tier 2 Compliant
 Distributed Redundant
 Single Utility
 MV Paralleling
Switchgear
 Unit Substations
 Utility on the bus
 Breaker pair transfer
 Reliability
 (N4, n3, P0.98) = 0.99766
 0.999
 (N4, n3, P0.999) = 0.99999
 (0.99766)(0.999)(0.99999)= 0.99645
B

17. Parallel Redundant, 2N, T4, PR,
LV $1700 $600 $600 $2900 99.994%17
Phase 1 Phase 2 Phase 3 Total
Reliability
 2N System
 Tie Breaker
 Tier 4 Compliant
 Parallel Redundant
 Single Utility
 LV Paralleling
Switchgear
 Utility on the bus;
150KAIC
 Breaker pair transfer
 Reliability
 (N4, n2, P0.98) = 0.99996
 1- ((1-0.999) X 1-(0.999)) = 0.99999
 N4, n2, P0.999 = 0.99999
 (0.99996)(0.99999)(0.99999)= 0.99994
C

18. Cost vs Reliability
18

19. Distributed Redundant, N+1,T4,
DR $1200 $600 $600 $2400 99.742%19
Phase 1 Phase 2 Phase 3 Total
Reliability
 N+1 System
 Tier 4 Compliant
 Distributed Redundant
 No Paralleling
 Main –Tie –Main
 65KAIC Switchgear
 Breaker pair transfer
 Day One = 2X1875
 Reliability
 (N4, n3, P(0.98)( 0.999) = 0.99742
D

20. Block Redundant N+1,T4, BR
$1100 $550 $550 $2200 99.742%20
Phase 1 Phase 2 Phase 3 Total
Reliability
 N+1 System
 Tier 4 Compliant
 Block Redundant
 No Paralleling
 Catcher Bus
 65KAIC LV Switchgear
 Breaker pair transfer
 Day One = 2X1750
 Reliability
 (0.98)( 0.999) = 0.97902
 (N4, n3, P0.97902) = 0.99742
E

21. Cost vs Reliability
21

22. Single Bus, N+2, T2, DR
$850 $600 $600 $2050 99.745%22
Phase 1 Phase 2 Phase 3 Total
Reliability
 N+2 System
 Tier 2 Compliant
 Distributed Redundant
 Paralleling on Gen
 65KAIC Switchgear
 Breaker pair transfer
 Day One = 2X1000
 Reliability
 (N12, n10, P0.98) = 0.99846
 0.999
 (N4, n3, P0.999) =0.99999
 (099846)(0.99999) (0.999)
 = 0.99745
F

23. Redundant Bus, N+2, T3, DR
$1000 $600 $600 $2200 99.845%23
Phase 1 Phase 2 Phase 3 Total
Reliability
 N+2 System
 Tier 3 Compliant
 Distributed Redundant
 Paralleling on Gen
 65KAIC Switchgear
 Breaker pair transfer
 Day One = 2X1000
 Reliability
 (N12, n10, P0.98) = 0.99846
 1-(1-0.999)(1-0.999)= 0.99999
 (N4, n3, 0.999)= 0.99999
 =0.99845
G

24. Redundant Bus, N+4, T4, PR
$1040 $540 $790 $2370 99.998%24
Phase 1 Phase 2 Phase 3 Total
Reliability
 N+4 System
 Tier 4 Compliant
 Parallel Redundant
 Paralleling on Gen
 150KAIC Switchgear
 Breaker pair transfer
 Day One = 2X1000
 Reliability
 (N14, n10, P0.98) = 0.99969
 1 – (1-0.999)(1-0.999)= 0.99999
 0.99999 x 0.99999= 0.99998
H

25. Topology Phase
1
Phase 2 Phase 3 Total
(Thousand)
Reliability
98%, 99.9%
Reliability
94%, 99%
A Medium Voltage, 2N, PR, T4 $2250 $750 $750 $3750 99.994% 99.91%
B Medium Voltage, N+1, DR, T2 $2000 $650 $650 $3300 99.645% 97.02%
C Parallel Redundant, LV, 2N, PR, T3 $1700 $600 $600 $2900 99.994% 99.91%
D Distributed Redundant, LV, N+1,DR, T3 $1200 $600 $600 $2400 99.742% 97.94%
E Block Redundant, LV, N+1, BR, T3 $1100 $550 $550 $2200 99.742% 96.76%
F Single Bus, LV, N+1, DR, T2 $850 $600 $600 $2050 99.745% 95.87%
G Redundant Bus, LV, N+2, DR, T3 $1000 $600 $600 $2200 99.845% 96.83%
H Redundant Bus. LV, N+4, PR, T4 $1040 $540 $790 $2370 99.998% 99.89%
Comparison of Options
25

26. Conclusions
26
 Systems that used integrated paralleling were
more reliable at lower costs
 Availability was improved by redundant buses,
but reliability was only slightly affected
 Medium Voltage increased the price but not
reliability
 Scalability offers modular reliability
improvements

27. University of Utah
 11 MW design, but only 5MW installed
 20,000 Gallon fuel
27

28. One-Line
28

29. Outcomes and Conclusions
 Power usage is not as high as forecasted
 Provisions for future growth are available
 Bi-fuel may have improved fuel storage risk
 Smooth project execution
 Video
29

30. Venyu
 Baton Rouge
 40,000SF Co-Location
30

31. One-line
31

32. Factors and Decisions
 Redundant buses allow concurrent
maintenance
 Automatic transfer is fault tolerant
 All generators on line in 8 seconds
 Second floor services and high efficiency
transformers are other innovative aspects
 Video
32

33. C7 Data Center
 Salt Lake City
 50,000SF Co-Lo
33

34. One-Line
34

35. Outcomes and Conclusions
 Innovation is a key to success at C7
 Power usage in the facility is lower than
expected
 Energy efficient servers and cooling may
cause the expansion at this facility to never be
built
 Other buildings are receiving the same units
 Future large expansion is planned with this
topology
35

36. Green House Data
 Cheyenne Wyoming
36

37. Green House Data
37

38.  Cheyenne Wyoming
 5MW total final
 N + 1
 2MW first phase
 Single bus
 Distributed Redundant
Outcomes and Conclusions
38

39. Topology Phase
1
Phase 2 Phase 3 Total
(Thousand)
Reliability
98%, 99.9%
Reliability
94%, 99%
A Medium Voltage, 2N, PR, T4 $2250 $750 $750 $3750 99.994% 99.91%
B Medium Voltage, N+1, DR, T2 $2000 $650 $650 $3300 99.645% 97.02%
C Parallel Redundant, LV, 2N, PR, T3 $1700 $600 $600 $2900 99.994% 99.91%
D Distributed Redundant, LV, N+1,DR, T3 $1200 $600 $600 $2400 99.742% 97.94%
E Block Redundant, LV, N+1, BR, T3 $1100 $550 $550 $2200 99.742% 96.76%
F Single Bus, LV, N+1, DR, T2 $850 $600 $600 $2050 99.745% 95.87%
G Redundant Bus, LV, N+2, DR, T3 $1000 $600 $600 $2200 99.845% 96.83%
H Redundant Bus. LV, N+4, PR, T4 $1040 $540 $790 $2370 99.998% 99.89%
Comparison of Options
39

40. Observations and Conclusions
 Short lead-times, lower cost, and risk reduction
are driving decisions.
 New technology is available and being
adopted
 Standard components are favored over
custom
 Scalability is more important than before
 Many solutions exist to accomplish goals
40

41. Questions
 Thank You
41