Method for measuring active power and measuring device therefor

摘要

It is in principle possible, for active power measurement in a single- or multi-phase AC network to measure current through and voltage across the load in each phase, to multiply the temporally related values with each other and subsequently to average over at least one time period. It is more favourable to digitise a current proportional to the rectified load current and subsequently to multiply the digitised values individually with associated normalised voltage values stored in a ROM table and to add them. The mean value can then be calculated from the result. The number of measured values is thereby kept low, since only current values are measured, whereas the associated (normalised) voltage values are read from a ROM table.