The high voltage arm of the measuring branch, being formed of the capacitance
CX in series with the hypothetical resistance Rx of the test object, is grounded via
the tunable resistor R3 providing the LV arm. The HV arm of the reference divider
being formed by the loss-free standard capacitor CN is grounded via a parallel
connection of the resistor R4 and the tunable capacitor C4, both forming the LV
arm.