IEC 62153-4-17:2018 applies to the testing of the reduction factor of multi-element metallic cables used in analogue and digital communication and control. The described method is generally applicable to all screened metallic cables.
The reduction factor describes the screening effectiveness of a cable screen at frequencies below 1 kHz with a ratio of voltages describing the screened and unscreened situation. During the measurement, the cable under test is connected to a specific current loop arrangement.