Alternating-Current Measuring Instruments as Discriminators against Harmonics

Alternating-current measuring instruments are classified and a brief description of a method for obtaining each one of them is given. They are then discussed from the standpoint of the increase in reading which can be caused by harmonics added to the pure tones. It is shown that, under certain conditions, the linear detector may be superior to other forms of alternating-current instruments in that the increase due to harmonics is the smallest, whereas the full-wave square-law detector or energy measuring device has the unique superiority of having an increase which is independent of the phase relations between the fundamental and the harmonics and between the harmonics themselves.