Digitally measuring alternating voltages and currents - registering deviations of frequency from nominal value and eliminating frequency dependent errors from effective values

摘要

The ready position of scan values (u(t1)....u(tN)) to the scan time points (t1...tN) produced by a constant scanning frequency provides a window (W1) determined by the period duration of the alternating dim.(u) and the arguments are the effective value (U(t1)) related to the first commencement time point (t1) and calculated after comparison. Further effective values (U(t2).....U(tN)) are calculated via scanning values (u(t1 + n .....u(tN + n) after comparison in the window (W1) displaced by time cycles (n = 1,2 .....N). The measurement value of the alternating dim. (u) is formed out of the average value of the effective values (U(t1)....U(tN)). The measurement value of the alternating dim. (n) is represented by the average value of the effective values (U(t1).....U(tN/2)), which are calculated after comparison via scan values (t(t1 + n .....u(tN + n) of the window (W1) displaced by time cycles (n = 0,1 .....tN/2). ADVANTAGE - Uses constant frequency for scanning process.