A current comparator bridge for measuring the value of an unknown capacitor includes a current comparator having a first comparator winding with an adjustable tap which is connected to one side of a standard capacitor and a second comparator winding connected to one side of an unknown capacitor, a high voltage source being connected to the other side of the capacitors. The current comparator is provided with a detection winding for detecting when the ampere-turns in the first and second comparator windings are equal and opposed to each other. In addition to the current through the standard capacitor being applied to the first comparator winding, the bridge includes a circuit to add a current through a standard conductance to the first comparator winding as well as circuits to compensate for errors. The detection winding is connected to a current-to-voltage converter with an adjustable gain which provides a signal to a phase sensitive detector. A reduced replica of the high voltage source is also applied to the phase sensitive detector which provides output signals E.sub.o and E.sub.90 to indicate when the bridge is balanced for both in phase and quadrature components respectively. The values of the capacitance and dissipation factor for the unknown capacitor can then be determined from the balanced condition of the bridge which is designed so that it can be automatically controlled by a microprocessor and switch controller.
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