Electrical power measuring devices.

摘要

An electrical power measuring device wherein signals (Vi, Vv) representing one of the current and voltage supplied to a lead are applied to the input of a sigma delta modulator (9), and the state (0 or 1) of the modulator output together with the polarity of the other one of the voltage and current values, is used to determine the sense in which the digital signals representative of successive samples of the other one of voltage and current values are accumulated in an accumulator (11). The count in the accumulator (11) consequently increases at a rate representative of the power supplied to the load. <IMAGE>