IEC 62153-4-3 specifies the triaxial test method for measuring the surface transfer impedance of cable screens and connectors. Surface transfer impedance quantifies how much electromagnetic energy couples through a cable shield from external fields to the internal conductors.
The test uses a triaxial test fixture consisting of the cable under test placed inside a precisely dimensioned outer tube. A current is injected on the outer surface of the cable shield and the voltage developed on the internal conductor is measured, typically expressed in milliohms per meter.
This measurement is fundamental for characterizing the shielding quality of screened cables used in aerospace, military, telecommunications, and industrial applications. Lower transfer impedance values indicate better shielding performance.