A method and a measurement apparatus are provided for determining the
transition impedance between two electrode parts of a subdivided neutral
electrode used in high-frequency surgery. These make it possible for the
purely capacitive component of the transition impedance to be measured.
For this purpose a resonant-frequency shift is measured, which occurs
when a basic resonant circuit is expanded to an expanded resonant circuit
by incorporating the two electrode parts into it in parallel. In
particular, in order to determine the basic resonant frequency of the
basic resonant circuit and/or the sample resonant frequency of the
expanded resonant circuit, the phase shift between current and voltage is
measured and the frequency is adjusted until current and voltage are in
phase.