1. PowerSouth Lowman AC/DC Essential Voltage System

2. Essential Voltage System Original Design Weaknesses Event Report New Design

3. Original Design Overview

4. Original Design Weaknesses Manual operation Break-before-make switching Lack of redundancy Lack of Data/Alarms

5. 480V Emergency Section Manual breaker operation with Kirk-key interface

6. Diesel Generator No adequate PM testing on Diesel Generator

7. Chargers/Batteries Single point of failure with one charger

8. Inverters Single point of failure with one inverter feeding primary and secondary control power in some areas

9. Event Report

10. Event Recap Normal operation Unit 2 charger is impaired with no direct alarming

11. Event Recap (cont.) Batteries become depleted Switchgear relaying begins to alarm

12. Event Recap (cont.) Standby Charger was swapped to Unit 2 DC breaker from Standby Charger tripped numerous times

13. Event Recap (cont.) AC Switchgear not able to transfer to station service No DC power Turbine Trips and spins down without adequate lube or seal oil supply.

14. Rotor/Bearing Damage

15. Hydrogen Seal Casing Damage

16. Need for Improvement Safety Reliability Adequate feedback Automated operation where possible Redundancy

17. Upgraded System Overview

18. 480V Automatic Transfer Normal Feed Emergency Feed

19. 480V Automatic Transfer Switch

20. 480V Paralleling Switchgear 480V Paralleling SWGR

21. Diesel Generator/ Paralleling Switchgear Protective Relay Sync Indication Unit 2 Feed Unit 3 Feed Diesel Gen Feed

22. 350kW Diesel Generator

23. Redundant Charging with Standby Utility Fed Charger Emer. Fed Charger Unit 2 Batteries Standby

24. Battery Chargers Unit 3 Chargers Unit 2 Chargers Standby Charger

25. Batteries Unit 3 Batteries Standby Batteries Unit 2 Batteries

26. DC Switchboard/Distribution

27. DC Switchboard Unit 2 Battery Breaker 2A Charger Feed 2B Charger Feed

28. Dual Inverters Inverter 2A Inverter 2B

29. Dual Inverters Inverter 2A Inverter 2B Inverter 3A Inverter 3B

30. 120V Essential Power Transformers 120V Essential Power Transformer 2A 120V Essential Power Transformer 2B

31. Control Screen

32. DC Voltage Visual

33. Critical Event Response Open

34. Questions/Comments?