Electronic measurement circuit - designed esp. for electricity meter with variables derived from mains voltage and load current

摘要

Mains voltage and load current variables are applied to a multiplier whose output is applied through an invertor and/or a switch to an integrator for the mean value formation. Its upper and lower limits are determined by a comparator which reacts on the switch. A constant reference quantity (U ref) is added to two summation points (A, B) to both above mentioned variables (UU.UI). These sums are then applied to the multiplier (1) and the further linear measurement part (2-5). Fundamental frequency produced in the linear measurement part by the reference voltage (U ref.) is removed, or its pulses blanked out in the comparator by means of a fixed frequency oscillator.