Main Generating

Question 1

Unit 2 is operating at rated power. A loss of startup transformer NAN-X01 occurs due to a transformer fault. Several minutes later, a reactor trip occurs due to an unrelated failure in PPS. Which one of the following describes how the Unit 2 electrical distribution system would respond?

A. A coastdown trip of the main generator would result in the eventual de-energization of NAN-S01.
B. The Train B Emergency Diesel Generator will start and close in on PBB-S04.
C. A sequential trip of the main generator would result in a fast bus transfer of both NAN-S01 and NAN-S02.
D. A sequential trip of the main generator would result in the failure of fast bus transfer of NAN-S02 and NAN-S01.

Answer 1

Answer: A

Question 2

Operators have just completed a Main Generator field flashing and the following conditions exist: Turbine is at 1800 rpm. Transfer to AC regulation has been accomplished. Generator terminal voltage is 23.5 KV. Synch selector switch is in “COMP-MANUAL”. Synchroscope is 5° from top dead center. Synchroscope is rotating slow in the fast direction. Which one of the following is correct? When the handswitch for the selected Generator Output breaker is taken to CLOSE, the breaker:

A. can be closed outside the acceptable angles for synchronizing.
B. will not close.
C. closes but subsequently trips open.
D. will close when the synchronizing check permissive is satisfied.

Answer 2

Answer: D

Question 3

A Loss of Offsite Power has occurred. The reactor and main turbine have tripped. NAN-S01 and NAN-S02 have load shed all loads except the RCPs. Main generator output breakers have tripped. The unit auxiliary transformer is still in service. Which one of the following describes the type of main turbine generator trip which has occurred?

A. Simultaneous Trip.
B. Sequential Trip.
C. Coastdown Trip.
D. Delayed Sequence Trip.

Answer 3

Answer: C