Power measuring apparatus

摘要

Apparatus for measuring power consumed by a load connected via mains to a source of alternating current having a given fundamental frequency includes means for generating a first signal proportional to the instantaneous voltage across the load and a transformer secondary toroidally wrapped around one of the mains for generating a second signal proportional to the instantaneous current through the load. Tuned amplifiers of narrow band pass amplify the signals before they are fed to a square low multiplier means including photooptical devices.