Q50 — EDG Minimum Load After Paralleling
064 A1.08 (3.1)
Given:
• Unit 1 is at 100% Power.
• The 1A EDG surveillance test is in progress in accordance with S1.OP-ST.DG-0001, 1A Diesel Generator Surveillance Test.
• The operator has just closed the generator output breaker.
• 1A diesel generator output meter (1WM182) indicates 50 KW.
In accordance with S1.OP-ST.DG-0001, which ONE of the following completes both statements?
The operator is required to immediately raise diesel generator load to __(1)__ KW to prevent __(2)__.
• Unit 1 is at 100% Power.
• The 1A EDG surveillance test is in progress in accordance with S1.OP-ST.DG-0001, 1A Diesel Generator Surveillance Test.
• The operator has just closed the generator output breaker.
• 1A diesel generator output meter (1WM182) indicates 50 KW.
In accordance with S1.OP-ST.DG-0001, which ONE of the following completes both statements?
The operator is required to immediately raise diesel generator load to __(1)__ KW to prevent __(2)__.
A. 1) 250
2) excessive accumulation of oil in the exhaust system during low load conditions
2) excessive accumulation of oil in the exhaust system during low load conditions
B. 1) 250
2) tripping the output breaker on reverse power
2) tripping the output breaker on reverse power
C. 1) 500
2) tripping the output breaker on reverse power
2) tripping the output breaker on reverse power
D. 1) 500
2) excessive accumulation of oil in the exhaust system during low load conditions
2) excessive accumulation of oil in the exhaust system during low load conditions
▶ Show Answer & Explanation
✓ C. Correct. IAW S2.OP-ST.DG-0001 step 4.3.8.1.c Caution, to prevent tripping the EDG output breaker on reverse power, generator load must be immediately raised to ≥ 500 KW after the breaker is closed.
✗ A. First and second parts are incorrect. Minimum is 500 KW to prevent tripping output breaker on reverse power. Plausible because the operator may incorrectly determine the required KW loading and the reason for raising EDG output promptly. S1.OP-SO.DG-0001 P&L 2.19 states: Exhaust Fire — Low load operation allows oil to accumulate in the exhaust system. If a significant amount of oil is allowed to accumulate in the exhaust system followed immediately by sudden high diesel loading, there is a potential of initiating an exhaust fire. Gradual diesel loading will help avoid an exhaust fire.
✗ B. First part is incorrect. Minimum is 500 KW to prevent tripping output breaker on reverse power. Second part is correct. Plausible because the operator may incorrectly determine the required KW loading.
✗ D. First part is correct. Second part is incorrect. Minimum load is to prevent tripping the output breaker on reverse power. Plausible because the applicant may confuse the P&L from S1.OP-SO.DG-0001 for low load operation to prevent exhaust fire.
Ref: NOS05EDG000-15, S1.OP-SO.DG-0001 (R39) | LO: NOS05EDG000-15, Obj 12 — Discuss the procedural requirements associated with the Emergency Diesel Generator, including an explanation of major precaution and limitations in the Emergency Diesel Generator procedure | Source: New | Cognitive: Fundamental/Memory
Connections
- Related systems: EDGs
- Related procedures: S2.OP-ST.DG-0001 — Emergency Diesel Generator Surveillance Test
- Related exam: 2022 NRC Written Exam