| 摘要 |
PURPOSE:To detect even apparent power together with reactive power and to detect active power with high precision, by adding a circuit which detects the apparent-power by using the output voltage (e) of a signal synthesizing circuit. CONSTITUTION:The output voltage (e) of the signal synthesizing circuit is used to find the reactive power Eq by a mean value amplifying circuit 2 and further, a rectified mean value amplifying circuit 3 is used to find the apparent power Es. The circuit 3 rectifies the voltage (e) on full-wave basis and then obtains the mean value in at least a one-cycle period to output the electric power Es. In this case, a severe method of finding the active power Eq by arithmetic Ep= (E<2>s-E<3>q)1/2is not employed and an approximate value is found by a simple method. Namely, an absolute value circuit 4 finds the absolute value of the reactive power Eq, and an operational amplifying circuit 5 finds the difference in absolute value between the apparent power Eq and reactive power Eq and outputs it as the active power Ep. |
