1. Neptune Power Versions compared 1 All rights reserved © 2003, Neptune Power sub-system Versions 1 and 2 Key features V2 is functionally equivalent to V1 in safe mode (mostly) Operation of the delivery system is autonomous Several modes of operation are identified – Normal – Node Connecting – Fault Clearing – Fault Locating Operation in these modes is not SOP for a power system! The existence of these modes enables component stress to be reduced during system operation

2. Neptune Power Versions compared 2 All rights reserved © 2003, Neptune Version 2 physical location options Power sub unit can be in the BU or Node 10A circuit 1A circuit BU Science Node Pressure- Cases 1A circuit 10A circuit

3. Neptune Power Versions compared 3 All rights reserved © 2003, Neptune Concept of operations Design continues to be refined Simple reliable operation is key Voltage is used as a signal to the autonomous BU control

4. Neptune Power Versions compared 4 All rights reserved © 2003, Neptune Concept of operations Voltage Mode m(Meaning) Operation to be performed +500*Fault locationClose all BB breakers Disconnect all science nodes - 500*Fault clearingOpen breaker closest to fault -1000Connect Science Node Measure resistance of spur cable to science node: close switch if good -5000 (or more) NormalInternal monitoring only: No switch operations at full voltage Appropriate sequencing gives unambiguous operation * These mean current-limit operation at the shore station

5. Neptune Power Versions compared 5 All rights reserved © 2003, Neptune Concept of operations Un-powered +500V Fault Locating Mode, + 500 V Initial switch state is unknown Shore station is in current limit operation Regardless of whether a fault is present – Positive voltage is sensed – Backbone breaker is closed – Science node connection is opened If there is a fault, its location is measured from shore Return to unpowered state after fault location determined

6. Neptune Power Versions compared 6 All rights reserved © 2003, Neptune Concept of operations Un-powered -500V Fault Clearing Mode, -500V Initial BB switch state is closed Shore station is in current-limit operation If a fault is present – Time-coordinated protection begins when current becomes non-zero – Unit closest to fault trips first If no fault is present – Backbone breakers remain closed In either case, status is stored

7. Neptune Power Versions compared 7 All rights reserved © 2003, Neptune Concept of operations - 500V -1000V Science Connecting Mode, -1000 V Initial science node switch state is open Shore station is constant voltage operation Spur cable resistance is measured at low current – If no fault detected, spur switch closes – If fault detected, spur switch stays open In either case, status is stored

8. Neptune Power Versions compared 8 All rights reserved © 2003, Neptune Concept of operations -1000V-10kV Normal Mode, -6000 V to – 10,000 V The control knows what the switch status is The control knows that is is in the Normal Mode If a fault occurs during Normal Mode operation – No switch action results – Shore station enters current limit mode

9. Neptune Power Versions compared 9 All rights reserved © 2003, Neptune Concept of operations Un-powered -10kV Controlled shutdown from normal mode Shore station shuts the system down There is no change in the state of any switch The location of faults, if any, is not known to the shore station If the shutdown is not because of a fault, the fault location step can be omitted

10. Neptune Power Versions compared 10 All rights reserved © 2003, Neptune Circuit description Simplified circuit, un-powered Control To Science 0V

11. Neptune Power Versions compared 11 All rights reserved © 2003, Neptune Circuit description Fault Location mode Power Feed output to +500V Control To Science +500V

12. Neptune Power Versions compared 12 All rights reserved © 2003, Neptune Circuit description Control To Science +500V Fault Location mode Start up supply charges

13. Neptune Power Versions compared 13 All rights reserved © 2003, Neptune Circuit description Fault Location mode Next cable section connected Control To Science +500V

14. Neptune Power Versions compared 14 All rights reserved © 2003, Neptune Circuit description Fault Location mode Second start up supply charges Control To Science +500V

15. Neptune Power Versions compared 15 All rights reserved © 2003, Neptune Circuit description Fault Location mode Second relay closes Control To Science +500V

16. Neptune Power Versions compared 16 All rights reserved © 2003, Neptune Circuit description Fault Location mode Zeners power control if fault Control I +500V

17. Neptune Power Versions compared 17 All rights reserved © 2003, Neptune At the end of Fault Locating sequence: All backbone breakers are closed (onto fault, if there is one) All spur cable switches are open Next part of sequence is Fault Clearing

18. Neptune Power Versions compared 18 All rights reserved © 2003, Neptune Circuit description Fault Clearing mode Supply to – 500 V, current limited Control To Science -500V

19. Neptune Power Versions compared 19 All rights reserved © 2003, Neptune Circuit description Control To Science -500V Fault Clearing mode Backbone switches open if appropriate

20. Neptune Power Versions compared 20 All rights reserved © 2003, Neptune At the end of Fault Clearing sequence: Nearly all backbone breakers are closed If there is a fault, closest breakers are open All spur cable switches are open Next part of sequence is Science Node Connecting

21. Neptune Power Versions compared 21 All rights reserved © 2003, Neptune Circuit description Science Connecting mode Power feed output increased to -1000V Control To Science -1000V

22. Neptune Power Versions compared 22 All rights reserved © 2003, Neptune Circuit description Control To Science -1000V Science Connecting mode Spur Cable switches closed if not faulted

23. Neptune Power Versions compared 23 All rights reserved © 2003, Neptune At the end of Science Connecting sequence: Nearly all backbone breakers are closed If there is a fault, closest breakers are open All spur cable switches are closed (unless faulted) Next part of sequence is Normal Operation

24. Neptune Power Versions compared 24 All rights reserved © 2003, Neptune Circuit description Power feed output increased to 10kV, system fully powered Control To Science -10kV