USCG Exam PracticeElectrical measuring devices and instrumentation
An AC voltmeter connected to a 440 V shipboard distribution bus will display which value of voltage?
- A. The peak voltage of approximately 622 V
- ✓ The RMS voltage of 440 VCorrect
- C. The average half-cycle voltage of approximately 280 V
- D. The instantaneous voltage at the moment of connection
Why B is correct
AC voltmeters and ammeters are calibrated to read RMS values. For a sine wave, RMS equals 0.707 times the peak; the 440 V nameplate rating is the RMS value. The peak of a 440 V RMS system is approximately 622 V, but that is not what the meter displays.
Cited:NEETS Mod. 2 §1-2