Digital circuit for measuring of power

The invention describes a cheap and uniform circuit generating signals representative of all electric power parameters by digitally processing input analogue measuring signals. The circuit of the invention offers a novel way of digitally processing the input signals. It renders the use of simple first order SIGMA - DELTA modulators possible. According to the invention computation of the root-mean-square value of the input signal is performed in a way that the input signal is multiplied by its normalized value. The product obtained by said multiplication is accurate in the entire dynamic range. Thus a satisfactory accuracy in the dynamic range 1:1000 is reached by first order input SIGMA - DELTA modulators.