ディジタル位相検出システムを用いるコンデンサの精密測定

抄録

A digital impedance measuring system based on the digital phase detecting system (DPD) has been developed for precise measurement of impedance. This measuring system consists of a personal computer with an ac-to-dc converter, a pair of current-to-voltage converters (CVC) and a frequency synthesizer. An unknown impedance and a standard resistor are connected to the frequency synthesizer in parallel. A ratio of the unknown impedance to the impedance of the standard resistor is calculated from the output voltages of the CVCs which are measured by means of DPD. The impedance of a capacitor of which nominal value is 0.1 μ F is measured at 50 Hz. It is estimated that the uncertainties of the measured values for capacitance and loss-angle are 0.006% and 0.05 mrad respectively excepting the uncertainty of the standard resistor.