IEC 62153-4-17:20 18适用于模拟和数字通信和控制中使用的多元金属电缆的折减系数测试。所描述的方法通常适用于所有屏蔽金属电缆。 降低因子描述了电缆屏蔽在低于1kHz的频率下的屏蔽有效性，其电压比率描述了屏蔽和未屏蔽的情况。在测量过程中，被测电缆连接到特定的电流回路布置。

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.