Method of measuring conducted disturbance using both capacitive voltage probe and current probe

We developed a capacitive voltage probe with an electrostatic shield which can measure the common-mode voltage for any kind of cable. The configuration of the capacitive voltage probe is shown. It consists of two coaxial electrodes, a cable fixture, and a high-input impedance amplifier operated by a battery. The outer electrode is used as an electrostatic shield. When a voltage appears between the cable and ground, an induced voltage occurs between its inner electrode and electrostatic shield. The induced voltage depends on the kind of cable, so the input-output factor of the probe is needed for every cable. We measured the common-mode voltage of telecommunication equipment using the capacitive voltage probe and an impedance stabilisation network (ISN) with the setup according to CISPR22.