USCG Exam PracticeAC circuits and theory
When preparing to parallel an incoming alternator onto a live bus, which four conditions must be satisfied before closing the paralleling breaker?
- ✓ Equal voltage, equal frequency, same phase sequence, and correct phase angle at the instant of closing.Correct
- B. Equal voltage, equal frequency, equal kVA rating, and matching power factor.
- C. Equal voltage, same phase sequence, matching excitation current, and equal governor settings.
- D. Equal frequency, same phase sequence, equal kVAR output, and correct phase angle.
Why A is correct
NEETS Mod. 5 §3-2 specifies all four conditions: equal voltage, equal frequency, the same phase sequence, and correct phase relationship at the instant of closing. Failure to meet any one — particularly phase angle — produces a violent current surge equivalent to a short circuit. kVA rating and excitation current are not among the four synchronizing conditions. (NEETS Mod. 5 §3-2)
Cited:NEETS Mod. 5 §3-2