| 摘要 |
1389506 Measuring electric power G WAURICK 5 Sept 1973 [5 Sept 1972] 41835/73 Heading G1U In the measurement of A.C. power, instead of the power factor cos # an 'energy factor' is used, this being derived from a signal resulting from multiplication of the instantaneous values of current and voltage and being equal to A-B divided by A+B, where A and B are respectively the integrated positive and negative values of the multiplied signal. The figure shows apparatus for deriving the 'energy factor' in a three-phase supply A, B, C. Multipliers Ia - Ic feed a first integrator 4 direct, whose output thus represents A-B and a second integrator 5 via invertors 6a - 6c and diodes 7a - 8c, the integrator 5 output thus representing A+B. Divider 9 provides the required quotient. The method is said to be particularly applicable to low power factor situations, where large currents would be needed to drive a normal two-coil wattmeter. |
