UPS Topologies and Multi-Module Configurations

1. UPS Topologies and Multi-Module Configurations IEEE IAS Section Atlanta GA November 17, 2008

2. Agenda • UPS Topologies • Line Interactive UPS • Delta Conversion UPS • Double Conversion UPS • Rotary UPS • UPS Design Market Drivers • UPS Components • Multi-Module UPS Configurations

3. Critical Power System Critical Load Generation Power Quality Distribution TVSS UPS PDU Servers Static Switch ATS Paralleling Switchgear

4. Line Interactive UPS

5. UPS Topologies – Line Interactive • Line Interactive • Runs on AC power from Utility and switches to Inverter if Utility source power quality is not within predetermined tolerance. Provides some surge protection. • Benefits – very efficient due to minimizing inverter run time • Disadvantages – limited surge protection • Application – Single computer or single rack

6. Delta Conversion

7. Delta Conversion • This Line Interactive system carries the load by using both the utility line by means of a Line Conditioner (Course Regulation) and two converters (Actually two inverters for Fine Regulation & Battery Charger). • This topology can regulate the load voltage by manipulating the secondary winding of the series t-former using the Series Converter. • Advantages • System does not go on battery for voltage fluctuations. • System efficiency is higher in normal mode. • Disadvantages • The unit needs two inverters, less reliability. • It circulates more ripple current to the batteries. • If the utility frequency goes out of tolerance, the unit must go on batteries.

8. Double Conversion UPS

9. UPS Topologies – Double Conversion • Double Conversion • Rectifies AC power into DC and then converts the DC back to AC. Provides clean power, completely isolated from the Utility during normal operation. • Benefits – No interruption of Power; Protects load from Utility spikes and Surges • Disadvantages – Greater losses than Line Interactive design

10. Rotary UPS

11. UPS Design Key Market Drivers • Reliability – • The 5 “9’s” - 99.999% up time • Efficiency • EPA Influence • Green Grid • Server Technology • Voltage • Outage Ride Through

12. Efficiency • Line Interactive UPS ~98% efficient • Double Conversion ~ 92% to 94% efficient • Methods to improve UPS efficiency • Eliminate Input and Output Transformers • “ECO” mode -Line interactive mode of operation • Data Center Efficiency Trends • Eliminate PDU transformers • Electrical Distribution Voltages

13. ECO Mode Overview

14. Server Technology • Server Voltages • Today –120VAC - 240VAC • 600V or 480V distribution with PDU transformers • 400V distribution without PDU transformers • Future – 277 VAC? ; 480VAC? • Server Power Outage Ride Through • CEMBA Curve – Now the “ITIC” Curve • Key Factor for “ECO” mode.

15. CBEMA-ITIC Curve for Double Conversion UPS

16. UPS Components • Rectifiers • SCR or IGBT • SCR – 6 Pulse and 12 Pulse • Inverters • IGBT with PWM • Static Switch Module • Transformers • Input Transformer • Output Transformer • Filters • Input Harmonic Filters

17. Rectifiers • IGBT Rectifier – Clean Input • High power sinusoidal rectification – low harmonics, limited need for filters • SCR Rectifiers • 6 Pulse – ~30% THD without filters – 7% with 5th Harmonic Filter • <5% with 5th and 11th filter • 12 Pulse – reduces harmonics by using parallel rectifiers with a phase shift ahead of one rectifier – requires input transformer • Lower efficiency than 6 Pulse • Rectifiers can be programmed to sequentially ramp up

18. 6 Pulse Current Input THD without filter THD with filter

19. 12 Pulse Rectifiers

20. 750 kVA - 6P vs 12P Rectifier – Energy Efficiency

21. Inverters • Converts DC power into AC using IGBTs and PWM • Several different methods to implement PWM

22. Static Switch Modules • Static Switch Module consists of breaker or contactor in series with back to back SCRs. • Static Switch modules can be continuous duty or momentary rated. Momentary rated Modules have a breaker or contactor in parallel. • Continuous duty is required for ECO mode operation.

23. Input Isolation Transformer Input Isolation Transformer – required for 12 Pulse Rectifier

24. UPS Output Transformer • Output Transformer • Isolates load from inverter • Provides greater protection to load during inverter failure • Transformer MTBF > IGBT MTBF

25. Input Filters • 5th Harmonic Cancellation • The filter is designed to cancel the current distortion that is most present on the 5th harmonic. • Power Factor Correction • The input filter also raises the input pf to approximately 0.93 with addition of capacitors. This will allow the generator to operate more efficiently delivering more real power

26. Multi-Module UPS Configurations • Paralleling UPS Modules • Capacity or Redundancy • Centralized Bypass • Distributed Bypass • Typical Parallel UPS Configurations • Isolated Redundant • Parallel Redundant • Distributed Redundant • System plus System

27. Parallel for Capacity • Multiple units = N • Not recommended for a N System (single system) • Frequently used for System + System (N+N) • MTBF impact • Parallel for capacity reduces MTBF value • Approximately half the MTBF of a single unit

28. Centralized Bypass

29. Distributed Bypass 29

30. Centralized Bypass Cabinet Distributed Bypass Configuration does not need this gear lineup

31. Parallel UPS Configurations Isolated Redundant Parallel Redundant Distributed Redundant System plus System

32. Isolated Redundant

33. Parallel Redundant

34. Distributed Redundant

35. System + System

36. Questions?

37. Contact Information: • Harry Handlin • GE Power Quality • Systems Engineer • P 205-789-7479 • E harry.handlin@ge.com