| 摘要 |
PURPOSE:To reduce the number of parts and obtain a detector with higher accuracy and lower cost by detecting components of voltage and a current different in phase by 90 deg. when a power-factor of a load is 1 to obtain the same phase and inverse phase signals of each voltage and current component, and by adding these signals over a period with a positive polarity. CONSTITUTION:A three-phase power source with phases a-c is connected to an inductive load 1, the voltage of a-c phases of this source is detected with a transformer 3 and further a current of the (b) phase is detected with a transformer 2. The relation between these voltage and current is that the current lags behind the voltage by 90 deg. in phase when a power-factor is 1 and a reactive current of an objective circuit is taken out as a voltage signal by taking these voltage and current as elements. Outputs of V01, V02 are inputted to arithmetic impedances Zi1, Zi2 of an amplifier 8 and can be outputted after being amplified with an arithemetic impedance Zf. Said outputs are estimated as an average value, and this average output can as it is be obtained as a reactive current of the value 1Xsintheta. |
