| 摘要 |
PURPOSE:To increase the linearity and temperature stability and to obtain high accuracy, by picking up the current and voltage of load with differential amplifier respectively, and taking the product of the outputs via the FET type photo coupler at the operational amplifier performing the operation at positive and negative half cycles. CONSTITUTION:The voltage between the load L and the terminal of the shunt R1 in series with it is in differential amplification A1, the output Vi is fed to the light emitting diodes D, D' of FET type photo couplers F, F' via the voltage current converter C, C', and the currents i+, i- proportional to the current of measured circuit flow. On the other hand, the voltage e is divided at the differential amplifier A2, and the output Ve is fed to the operational amplifiers A3, A4 via the resistors Rx, Rx' of the photo electric conversion element. The outputs V3 and V4 of the operational amplifiers A3, A4 appeared at positive and negative half cycles of current are fed to the input of the differential amplifier A6, and the product between Vi and Ve over the both periods of positive and negative polarity can be obtained from the output V5. Thus, the product between the voltage e and current i of the load L of measured circuit, i.e., electric power can be obtained. |
