Indicating Instruments at the Servomechanism Frequencies

Tests on indicating instruments excited with sinusoidal signals at the servomechanism frequencies show that under certain conditions they are the same useful and time-saving tools as when used at the power frequencies. These conditions are determined by the motional characteristics of the instrument and the desired accuracy. This paper describes the performance of conventional indicating instruments at these low frequencies, discusses what can be done to these instruments to make them more suitable for this service, and gives one example of what can be expected when an indicating instrument is designed expressly for servo system use.