USCG Exam PracticeHand/power tools, measuring instruments, and maintenance
Before paralleling an incoming generator to the bus, the operator uses the synchroscope and frequency meter together. The breaker should be closed at which point?
- A. When the synchroscope pointer is rotating rapidly clockwise, indicating the incoming machine is running fast
- B. When the frequency meter shows the incoming machine is exactly 1 Hz above bus frequency to ensure it picks up load immediately
- ✓ As the synchroscope pointer creeps slowly through the in-phase (twelve o'clock) positionCorrect
- D. When the power-factor meter reads unity, regardless of synchroscope position
Why C is correct
NEETS Mod. 3 §1-4 states that before paralleling generators the operator uses the frequency meter and synchroscope together to match frequency and phase, closing the breaker only as the synchroscope creeps slowly through its in-phase (twelve o'clock) position. Closing at any other position causes a damaging out-of-phase connection.
Cited:NEETS Mod. 3 §1-4