Double parabolic multiplier electrical power measuring circuit - has null error elimination by periodic squaring circuit interchanging

摘要

A double parabolic multiplier for the measurement of electrical power is designed to eliminate null point errors in such measurements. Parabolic multipliers generate the squares of the sum and difference of two variables (Iu, Ii) and produce the difference of the squares which is proportional to the product of the variables. When one of the variables has a zero value a null error occurs owing to differences in the squaring circuits (51, 511). In order to eliminate errors due to squaring circuit differences, the two squaring circuits (51, 511) are periodically interchanged by a switch (13) controlled by a time generator circuit (15).