3.4 AC Voltmeter

AC VOLTMETER

• Are designed in a manner . The function is measure the AC voltage under measurement. The main difference between AC and DC voltmeter circuit is the usage of a rectifier. The rectifier is used in order to transform the AC voltage into DC voltage.

GENERAL RECTIFIER TYPE

• Rectifier type instruments generally use a PMMC movement along with a rectifier arrangement. Silicon diods are preferred because of their low reverse current and high forward current ratings.

• The meterscale is usually calibrated to give the rms value of an alternating sine wave input.

• Practical rectifier are non-linear devices particularly at low values of forward current.