Current passing through a capacitor being measured is combined with programmable portions of oppositely phased current, and means are provided for deriving voltages from said combined current that lie within a given range regardless of the capacitance of the capacitor under test. A phase detector determines the phase angle between the latter voltage and the voltage causing current flow through the capacitor. The means for deriving the out-of-phase current includes a plurality of programmable, current transducer having their primary windings connected in series, one end of each secondary winding being connected to one end of its primary winding, and switches respectively connected to the other under the secondary winding. The means for deriving the voltage referred includes an operational amplifier and switches for connecting a similar plurality of current transformers in series with the capacitor being measured as in the feedback of the amplifier.