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- 1. richardsmith@asia.com Generator, Unit Hydrogen, Seal Oil, Stator Coolant, Demin Water Plant Operations Training Huntly Power Station: Units 1-4 Assessment ID: 8014, 8012, 8009, 8015, 8016 NZQA Unit Standard: 17413 Assessment /107 marks Candidate Name (First & Last):.............................................................................. Candidate ID:.................................................................................................... Date:..................................................................................................................
- 2. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 2 Instructions Answer all questions This is a closed book assessment Time: Two hours
- 3. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 3 Questions 1. List 4 possible causes of heat generation within the generator. (4 marks) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 2. Explain the terms “hot” and “cold” gas temperature. (2 marks) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 3. What is the normal operating pressure of hydrogen in the generator? (1 mark) a) 3.5 bar b) 3.0 bar c) 2.5 bar d) 4.0 bar 4. What is the normal operating pressure at the seals of the seal oil? (1 mark) a) 3.5 bar b) 3.0 bar c) 2.5 bar d) 4.0 bar 5. What system directly cools the hydrogen in the generator? (1 mark) a) Auxiliary cooling water b) Demin water c) Stator coolant d) Cooling water 6. What is the explosive range for hydrogen? (1 mark)
- 4. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 4 a) 20% - 75% b) 4% - 95% c) 20% - 95% d) 4% - 75% 7. Seal Oil / Hydrogen differential pressure is normally? (1 mark) a) 1.0 bar b) 0.6 bar c) 0.5 bar d) 1.5 bar 8. What are the advantages of using hydrogen as the cooling medium in a generator? (5 marks) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 9. What are the disadvantages of using hydrogen? (3 marks) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 10. When purging the generator from hydrogen to CO2, where is the CO2 admitted and why? (2 marks)
- 5. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 5 ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 11. What pressure is the generator depressurised to during a de-gas, before purging to CO2 commences. Why is this pressure maintained during the purge process? (2 marks) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 12. What is the function of the electric generator heaters, and when are they turned on? (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 13. Why is it important to maintain hydrogen purity? (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 14. What is the function of the hydrogen dryer? (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... 15. What is the purpose of the lute on the side of the hydrogen dryer? (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 16. Why is the auto hydrogen make-up system not normally used? (1 mark) ...................................................................................................................................................................................
- 6. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 6 ................................................................................................................................................................................... ...................................................................................................................................................................................
- 7. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 7 17. Referring to the diagram of the seal oil system (Figure 1); (15 marks) a) Discuss overall system function and operation. b) Name all key components (Use the encircled alphabetic reference callouts in your answer to refer to system features) Figure 1 ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ...................................................................................................................................................................................
- 8. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 8 ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 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- 9. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 9 18. Referring to the diagram of the Seal Oil Gas detraining chambers (Figure 2), briefly describe its operation. (5 marks) Figure 2 ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ...................................................................................................................................................................................
- 10. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 10 19. What is the purpose of the seal oil system? (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 20. What does the oil flow from the seal sides tell you and why is it important. State the implications of too little or too much flow in this sight glass. (4 marks) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 21. Explain the seal oil back-up Oil supply and how it works. (2 marks) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 22. When does the D.C. seal pump cut-in? (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ...................................................................................................................................................................................
- 11. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 11 23. What are the implications of the D.C. seal oil pump running for an extended time? (2 marks) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 24. Explain the importance of the differential between seal oil pressure and hydrogen pressure. (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 25. What is the Stator Coolant normal flow? (1 mark) a) 16.5 litre/minute b) 18.6 lites/minute c) 20 gallons/minute d) 5 gallons/minute 26. What is the Stator Coolant flow value that will generate the alarm Stator Coolant Flow Low? (1 mark) a) 14.2 litres/minute b) 14.2 gallons/minute c) 16.1 litres/minute d) 20 litres/minute 27. What is the Stator Coolant flow value that will start the standby pump? (1 mark) a) 14.2 litres/minute b) 14.2 gallons/minute c) 16.1 litres/minute d) 20 litres/minute 28. What is the trip associated with Stator Coolant flow? (1 mark)
- 12. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 12 a) 5.2 litres/minute b) 16.2 gallons/minute c) 8.1 litres/minute d) 14.0 litres/minute
- 13. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 13 29. Referring to the diagram of the stator coolant system (Figure 3). (14 marks) a) Discuss overall system function and operation b) Name all key components c) Describe the function and purpose of all labeled equipment items. (Use the encircled alphabetic reference callouts in your answer to refer to system features) Figure 3 ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ...................................................................................................................................................................................
- 14. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 14 ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 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- 15. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 15 ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 30. What types of coolers are used on the stator coolant? (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 31. Identify which strainers can be bypassed and for what reason. (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 32. Explain why the stator coolant system operates at a slightly lower pressure than the hydrogen system. (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ...................................................................................................................................................................................
- 16. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 16 33. Referring to the diagram of the Stator Coolant gas release chamber (Figure 4), describe operation including alarms and operating timers by completing the sentences provided. (6 marks) Figure 4 The Gas Release Chamber has three mobrey float switches which are operated as the stator coolant level lowers (due to gas collecting). The mobreys control the automatic gas release and initiate alarms as follows. When the top level switch is operated a _____ minute timer is started. As level continues to drop due to the gas leak, one of two situations will occur. Either a) The timer times out before middle float switch is reached in which case the gas will be released and a _________________________ alarm initiated b) Or if middle float is reached within the timer period and __________________ and ___________________________ alarms will be initiated and gas will be released. (If the "gas in coolant excessive" alarm is initiated it means that more than 50m³/24 hours is leaking and an inspection should be carried out). If the bottom Mobrey switch is operated then the ____________________________ will be initiated which means either:- c) The solenoid valve has not opened. d) Or the gas leakage is too much for the solenoid valve to cope with. The solenoid valve shuts when the level rises above the ______ Mobrey switch.
- 17. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 17 34. Explain the implications of the following alarms:- a) Stator coolant conductivity High (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... b) Gas in coolant (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... c) Gas in coolant excessive (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... d) Gas in coolant alarm inoperative (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... e) Stator coolant make-up tank level low. (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 35. What unit trip is associated with the stator coolant make-up tank? (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... 36. Referring to the diagram of the Generator Demin system (Figure 5); (13 marks)
- 18. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 18 a) Discuss overall system function and operation b) Name all key components c) Describe the function and purpose of all labeled equipment items. (Use the encircled alphabetic reference callouts in your answer to refer to system features) Figure 5 ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ...................................................................................................................................................................................
- 19. richardsmith@asia.com 8014 Written Assessment.doc Genesis Energy 19 ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... ................................................................................................................................................................................... 37. Where does the make-up to demin system come from? (1 mark) ................................................................................................................................................................................... ................................................................................................................................................................................... 38. Explain how the make-up tank level is controlled (1 mark) ................................................................................................................................................................................... ...................................................................................................................................................................................