Capacitance and dissipation factor measuring bridge - collects test voltage through high resistance directly from the tested capacitor

摘要

The collected test voltage is applied to a reference capacitor (CN) with a measurement circuit at its low voltage side; this circuit has a balancing point at an amplifier input, at which inverted current proportional to the current through the tested capacitor (CX), and two reference currents whose phases differ by 90 deg., are added; this sum is reduced to zero by the amplifier through a negative feed-back resistor; when the balance is not perfect, amplifier output voltage operates control elements for the capacitor and dissipation factor. All amplifiers are so designed, that a virtual zero potential exists at their inverting input; current flowing through the capacitor is applied directly or through resistors to the zero potential point of an amplifier (V1); its output voltage is applied through a resistor (R10) to the balancing point (AP); the balance is achieved by adjustment of currents (iCN, iRN).